Currents Sentence Examples
Did you notice the currents in the lake?
She could see the paths of currents.
He also made important contributions to the mathematical theory of electrodynamics, and in papers published in 1845 and 1847 established mathematically the laws of the induction of electric currents.
The water is deep right to the base of the cliff and owing to the winds and the strength of the ocean currents, navigation is dangerous.
Gas and oil radiators would be more properly termed " convectors," since they warm mainly by convected currents.
These were due to an enormous amount of exceedingly fine dust blown to a great height by that terrific explosion, and then universally diffused by the high atmospheric currents.
The diaphragms of these are mechanically connected to a small mirror and control its movement in accordance with the strength and direction of the received currents.
The telautograph is on a similar principle to the Cowper apparatus, the motion of the transmitting pencil or stylus used in writing being resolved by a system of levers into two component rectilinear motions, which are used to control and vary the currents in two distinct electrical circuits.
These coils are drawn down, by the magnetic action of the field on the currents in the coils, into the annular spaces, against the pull of the springs, more or less strongly, according to the strengths of the two line currents.
All cables of any great length are worked by reverse currents.
AdvertisementTo the sending currents, however, the bridge offers only apparent ohmic resistance due to the fact that the current entering the mid-point of the winding flows through the two halves or arms in opposite direction, and, owing to the winding being on the same iron core, the mutual inductive effect of the two arms on one another neutralizes the self-induction to the sending currents.
The electrical condition of the cable was then excellent, but unfortunately the electrician in charge, Wildman Whitehouse, conceived the wrong idea that it should be worked by currents of high potential.
He found, as others have dune, that if a battery, dynamo or induction coil has its terminals connected to the earth at two distant places, a system of electric currents flows between these points through the crust of the earth.
He also repeated the suggestion which Lindsay had already made that it might be possible to signal in this manner by conduction currents through the Atlantic Ocean from the United States to Europe.
A similar installation of inductive telephony, in which telephone currents in one line were made to create others in a nearly parallel and distant line, was established in 1899 between Rathlin Island on the north coast of Ireland and the mainland.
AdvertisementHence, when the coil at one fixed station was in action it generated high frequency alternating currents, which were propagated across the air gap between the ordinary telegraph wires and the metallic surfaces attached to one secondary terminal of the induction coil, and conveyed along the ordinary telegraph wires between station and moving train.
The suggestion of Bourseul and the experiments of Reis are founded on the idea that a succession of currents, corresponding in number to the successive undulations of the pressure on the membrane of the transmitting instrument, could reproduce at the receiving station sounds of the same character as those produced at the sending station.
The resistance of the microphone can thus be made a large fraction of the total resistance of the circuit in which it is placed; hence by using considerable currents, small variations in its resistance can be made to induce somewhat powerful currents in the line wire.
The single-wire earthed circuits used in the early days of telephony were subject to serious disturbances from the induction caused by currents in neighbouring telegraph and electric light wires, and from the varying potential of the earth due to natural or artificial causes.
The conditions permit of the circulation of the alternating currents of low periodicity, which are used for operating the bells, but in respect of the battery the circuit is open until the subscriber lifts the receiver, when the hook switch, thus released, joins the transmitter with one winding of an induction coil in series across the circuit.
AdvertisementAlthough the bells are constantly in circuit their high impedance prevents any appreciable interference with the telephonic currents.
In circuits possessing high resistance and capacity and low inductance per mile, telephonic currents are rapidly attenuated, and the higher the frequency the more rapid is the attenuation.
Oliver Heaviside showed mathematically that uniformly-distributed inductance in a telephone line would diminish both attenuation and distortion, and that if the inductance were great enough and the insulation resistance not too high the circuit would be distortionless, while currents of all frequencies would be equally attenuated.
The movement of emigration may be divided into two currents, temporary and permanentthe former going chiefly towards neighboring European countries and to North Africa, and consisting of manual laborers, the latter towards trans-oceanic countries, principally Brazil, Argentina and the United States.
Thus Microhydra lives amongst Bryozoa, and appears to utilize the currents produced by these animals.
AdvertisementProtohydra occurs in oysterbanks and Monobrachium also grows on the shells of bivalves, and both these hydroids probably fish in the currents produced by the lamellibranchs.
The deviation is of importance in the movement of air, of ocean currents, and to some extent of rivers.3 In popular usage the words " physical geography " have come to mean geography viewed from a particular standpoint rather than any special department of the subject.
While steam has been said to make a ship independent of wind and tide, it is still true that a long voyage even by steam must be planned so as to encounter the least resistance possible from prevailing winds and permanent currents, and this involves the application of oceanographical and meteorological knowledge.
Constant use, increased friction (m o r e especially at high speeds), and damage to the rotator will alter an ascertained log error; head or following seas, strong winds, currents and tidal streams also FIG.
In his episcopal capacity he attended several diets of the empire, as well as the opening meetings of the council of Trent; and the influence of his father, now chancellor, led to his being entrusted with many difficult and delicate pieces of public business, in the execution of which he developed a rare talent for diplomacy, and at the same time acquired an intimate acquaintance with most of the currents of European politics.
Weber, which was found capable of explaining all the phenomena investigated by Ampere as well as the induction currents of Faraday.
They occur in all the hot months, from June to October, and more rarely in November, and appear to be originated by adverse currents from the north meeting those of the south-west monsoon.
The diurnal mountain winds are very strongly marked on the Himalaya, where they probably are the most active agents in determining the precipitation of rain along the chain - the monsoon currents, as before stated, not penetrating among the mountains.
No man mastered more thoroughly the fundamental principles of government and the currents of feeling which influence the destiny of nations.
Hence we perceive two currents of tendency in the Getica.
The miracles recorded of Elijah and Elisha lie somewhat apart from the main currents of the history, the narratives themselves are distinct from the historical works in which they have been incorporated, and the character of some of the actions raises serious doubts and difficulties.
In ammeters for small currents it is customary to pass the whole current through the heating wire.
In instruments for larger currents the main current passes through a metallic strip acting as a bye-pass or shunt, and to the ends of this shunt are attached the ends of the working wire.
It is also necessary to notice that shunt instruments cannot be used for high frequencies, as then the relative inductance of the shunt and wire becomes important and affects the ratio in which the current is divided, whereas for low frequency currents the inductance is unimportant.
In constructing a hot-wire instrument for the measurement of high frequency currents it is necessary to make the working wire of a number of fine wires placed in parallel and slightly separated from one another, and to rpass the whole of the current to be measured through this strand.
In certain forms, hot-wire instruments are well adapted for the measurement of very small alternating currents.
In the case of ammeters intended for very small currents, the whole current can be sent through the coil, but for larger currents it is necessary to provide in the instrument a shunt which carries the main current, the movable coil being connected to the ends of this shunt so that it takes a definite small fraction of the current passed through the instrument.
Direct reading equidivisional movable coil ammeters can be made in various portable forms, and are very much employed as laboratory instruments and also as ammeters for the measurement of large electric currents in electric generating stations.
If there be two parallel wires through which currents are passing, then these wires are drawn together if the currents are in the same direction and pressed apart if they are in opposite directions.
This tendency can be resisted by giving a twist to the torsion head and so applying to the movable coil through the spring a restoring torque, which opposes the torque due to the dynamic action of the currents.
In these circumstances the torsional angle becomes a measure of the torque and therefore of the product of the strengths of the currents in the two coils, that is to say, of the square of the strength of the current passing through the two coils if they are joined up in series.
The instrument can therefore be graduated by passing through it known and measured continuous currents, and it then becomes available for use with either continuous or alternating currents.
Very convenient and accurate instruments based on the above principles have been devised by Lord Kelvin, and a large variety of these ampere balances, as they are called, suitable for measuring currents from a fraction of an ampere up to many thousands of amperes, have been constructed by that illustrious inventor.
This mode of suspension enables the conductor CC to vibrate freely like a balance, but at the same time very large currents can easily be passed through this perfectly flexible joint.
They are constructed for the measurement not only of continuousor unvarying butalsoof alternating currents.
In those intended for alternating currents, the main current through the movable coil, whether consisting of one turn or more than one turn, is carried by a wire rope, of which each component strand is insulated by silk covering, to prevent the inductive action from altering the distribution of the current across the transverse section of the conductor.
To avoid the creation of induced currents, the coil frames and the base boards are constructed of slate.
Unfortunately the island has hardly a regular harbour on any part of the coast; from its situation at the meeting, as it were, of seas, the currents in the neighbourhood are strong, and storms are very frequent.
In the water of the lake there is a general set of current towards the outlet at the strait of Mackinac, following the east shore, with slight circular currents in the main portion of the lake and at the northern end around Beaver island.
Surface currents are set up by prevailing winds, which also seriously affect water levels, lowering the water at Chicago and raising it at the strait, or the reverse, so as greatly to inconvenience navigation.
Similar currents exist in the Bosporus to those of the Strait of Gibraltar.
Almost all secondary water-courses, particularly if they have sluggish currents, are known as bayous.
They are comparatively inactive at all seasons; indeed, the action of the tides and back-waters and the tangle of vegetation in the sombre swamps and forests through which they run, often render their currents almost imperceptible at ordinary water.
Lakes of this class are sometimes formed by the choking of the mouth of feeble tributaries by silt deposited by the Red river where the currents meet.
Experience soon showed that .when the needful allowance was made for the time required to bring them out of harbour (two tides) and for the influence which the Channel currents must have upon their speed, it would be extremely 'rash to rely on a calm of sufficient length.
All ocean currents vary from year to year in their strength of flow and the main interest of physical oceanography in recent years has been the tracing-out of these variations and the search for the causes.
Entering the Barents Sea (that is, the area between the ice and the northern coast of Europe), these currents flow along the bottom.
Immediately on its discovery intense interest was aroused in the new invention, and the chemical effects of electric currents were speedily detected.
The colour depends in part upon the proportion of copper and zinc, and in part upon the current density, weaker currents tending to produce a redder or yellower metal.
A large number of specimens of a species are usually found together, since their only mode of spreading is during the ciliated larval stage, which although it swims vigorously can only cover a few millimetres an hour; still it may be carried some little distance by currents.
Among other subjects at which he subsequently worked were the absorption of gases in blood (1837-1845), the expansion of gases by heat (1841-1844), the vapour pressures of water and various solutions (1844-1854), thermo-electricity (1851), electrolysis (1856), induction of currents (1858-1861), conduction of heat in gases (1860), and polarization of heat (1866-1868).
Magnetic induction, like other fluxes such as electrical, thermal or fluid currents, is defined with reference to an area; it satisfies the same conditions of continuity as the electric current does, and in isotropic media it depends on the magnetic force just as the electric current depends on the electromotive force.
Various currents are then passed through the magnetizing coil, the galvanometer readings and the simultaneous magnetometer deflections being noted.
For specimens of large sectional area it is necessary to apply corrections in respect of the energy dissipated by eddy currents and in heating the secondary circuit.
This is attributed to the action of local currents set up between unequally magnetized portions of the iron.
Since that date it has more than once been suggested that the molecular currents producing magnetism might be due to the revolution of one or more of the charged atoms or " ions " constituting the molecule.
Ampere's experimental and theoretical investigation of the mutual action of electric currents, and of the equivalence of a closed circuit to a polar magnet, the latter suggesting his celebrated hypothesis that molecular currents were the cause of magnetism.
The ocean currents, the trade-winds blowing from the Australian mainland, and north-westerly storms from the Malayan islands, are no doubt responsible for the introduction of many, but not all, of these Malayan and Australasian species.
The predominant species are Madagascar plants and birds, which are carried by the currents and the winds..
There are winter winds from the Andes, but in the summer season there are cold currents of air from up-river (ventos da cima) which are usually followed by downpours of rain.
In winter the plateau is less heated, and cold currents of air from the west and south-west cause precipitation over a part if not all of this region.
A more instructive subdivision must be one which corresponds to the separate currents of thought and mental preoccupation which have been historically manifested in western Europe in the gradual evolution of what is to-day the great river of zoological doctrine to which they have all been rendered contributory.
He was rather a mediocre but not altogether obtuse man, who mistook tributary streams for the main currents of national thought.
Thus Ludwig was of opinion that the lymph-flow is dependent upon two factors, first, difference in pressure of the blood in the capillaries and the liquid in the plasma spaces outside; and, secondly, chemical interchanges setting up osmotic currents through the vessel-walls.
On the one hand he worked out the general theory of the magnetic circuit in the dynamo (in conjunction with his brother Edward), and the theory of alternating currents, and conducted a long series of observations on the phenomena attending magnetization in iron, nickel and the curious alloys of the two which can exist both in a magnetic and non-magnetic state at the same temperature.
The adjustment of the air currents in the different splits is affected by regulators which are placed in the return air-ways, and act as throttle valves to determine the volume of air in each case.
But as Mariotte observed similar obstructions even in glass pipes where no transverse currents could exist, the cause assigned by Guglielmini seemed destitute of foundation.
In endeavouring to make a pan of less power do as much and as good work as one of greater power, they have imagined many ingenious mechanical contrivances, such as currents produced mechanically to promote evaporation and crystallization, feeding the pan from many points in order to spread the feed equally throughout the mass of sugar being cooked, and so on.
The equatorial currents produce conditions differing from those existing at corresponding latitudes on the neighboring continent.
To admit of the free inflow and outflow of currents of water necessary for respiration, which is effected by means of filamentous abdominal tracheal gills, the two ends of the tube are open.
The nearly vertical vanes is balanced by the convection currents.
These seas are entirely dependent on the ocean for their regime, being filled with ocean water, though subject to influence by the land, and the tides and currents of the ocean affect them to a greater or less extent.
It is improbable, however, that the smooth and slender wire is much influenced by currents, and the best deep-sea soundings may be taken as accurate to within 5 fathoms.
Waves and tidal currents produce their full effects in that region, and in high latitudes the effect of transport of materials by ice is very important; while in the warm water of the tropics the reefbuilding animals and plants (corals and calcareous algae) carry on their work most effectively there.
A closer investigation of the numerous long, narrow banks which lie off the Flemish coast and the Thames estuary shows that they are composed of fragments of rock abraded and transported by tidal currents and storms in the same way that the chalk and limestone worn off from the eastern continuation of the island of Heligoland during the last two centuries has been reduced to the coarse gravel of the off-lying Dune.
Shore Deposits are the product of the waste of the land arranged and bedded by the action of currents or tidal streams. On the rocky coast of high latitudes blocks of stone detached by frost fall on the beach and becoming embedded in ice during winter are often drifted out to sea and so carry the shore deposits to some distance from the land.
Similar effects are produced in narrow waters by the action of tidal currents, and the influence of a steady wind blowing onor off-shore has a powerful effect in mixing the water.
In those localities, however, it is not the same water which varies in temperature with the season, but the water of different warm and cold currents which periodically occupy the same locality as they advance and retreat.
The arrangement of the isotherms thus affords a basis for valuable deductions as to the direction of ocean currents.
As the Arctic Basin is shut off from the North Atlantic by ridges rising to within 300 fathoms of the surface and from the Pacific by the shallow shelf of the Bering Sea, and as the ice-laden East Greenland and Labrador currents consist of fresh surface water which cannot appreciably influence the underlying mass, the Arctic region has no practical effect upon the bottom temperature of the three great oceans, which is entirely dominated by the influence of the Antarctic. The existence of deep-lying and extensive rises or ridges in high southern latitudes has been indicated by the deep-sea temperature observations of Antarctic expeditions.
Such old sea-ice when prevented from escaping forms the palaeocrystic sea of Nares; but, as a rule, it is carried southward in the .East Greenland and Labrador currents, and melted in the warmer seas of lower latitudes.
The latter often gives birth to prodigious icebergs and ice islands, which are carried northward by ocean currents, nearly as far as the tropical zone before they melt.
Although observations on marine currents were made near land or between islands even in antiquity, accurate observations on the high seas have only been possible since chronometers furnished a practicable method of determining longitude, i.e.
The difference between the position as determined astronomically and by dead-reckoning gives an excellent idea of the general direction and velocity of the surface currents.
The first comprehensive study of the currents of the Atlantic was that carried out by James Rennell (1790-1.830), and since that time Findlay in his Directories, Heinrich Berghaus, Maury and the officials of the various Hydrographic Departments have produced increasingly accurate descriptions of the currents of the whole ocean, largely from material supplied by merchant captains.
Direct observations of currents in the open sea are difficult, and even when the ship is anchored the veering and rolling of the vessel produce disturbances that greatly affect the result.
One of the indirect methods of investigating currents is by taking account of the initial temperature of the current and following it by the thermometer throughout its course; hence the familiar contrast between warm and cold currents, of which the Gulf Stream and the Labrador current are types.
Benjamin Franklin in 1775 and Charles Blagden in 1781, by means of numerous observations of temperature made on board the packets plying on the Atlantic passage, determined the boundaries of these two currents and their seasonal variations with considerable precision.
The differences of salinity support this method, and, especially in the northern European seas, often prove a sharper criterion of the boundaries than temperature itself; this is especially the case at the entrance to the Baltic. Evidence drawn from drift-wood, wrecks or special drift bottles is less distinct but still interesting and often useful; this method of investigation includes the use of icebergs as indicators of the trend of currents and also of plankton, the minute swimming or drifting organisms so abundant at the surface of the sea.
The general lines of the currents of the oceans are fairly well understood, and along the most frequented ocean routes the larger seasonal variations have also been ascertained.
The general scheme of ocean currents depends on the prevailing winds taken in conjunction with the configuration of the coast and its submarine approaches.
The trade-wind regions correspond pretty closely with westward-flowing currents, while in the equatorial calm belts there are eastward-running countercurrents, these lying north of the equator in the Atlantic and Pacific, but south of the equator in the Indian Ocean.
Where the trade-winds heap up the surface water against the east coasts of the continents the currents turn poleward.
Both currents unite off the coast of the United States and run northward, turning towards the east when they come within the influence of the prevailing westerly winds.
The accordance of wind and currents is so obvious that it was fully recognized by seafaring men in the time of the first circumnavigators.
The older theory of the origin of drift currents enunciated by Zoppritz in 1878 was modified as indicated above by Nansen in 1901, and Walfrid Ekman subsequently went further.
Such currents, due to the banking up of water, have a large share in setting the depths of the sea in motion, and so securing the vertical circulation and ventilation of the ocean.
The difference in density which occurs between one part of the ocean and another, shares with the wind in the production of currents.
If there were strong currents at the bottom of the ocean the uniform accumulation of the deposit of minute shells of globigerina and radiolarian ooze would be impossible, the rises and ridges would necessarily be swept clear of them, and the fact that this is not the case shows that from whatever cause the waters of the depths are set in motion, that motion must be of the most deliberate and gentlest kind.
Pettersson's view that ice-melting dominates the 'whole circulation of the oceans and regulates in particular the currents of the seas round northern Europe must, however, be looked on as carrying the explanation too far.
Wind and tide greatly alter the strength of these currents due to difference of density, and the surface outflow may either be stopped or, in the case of the belts, actually reversed by a strong and steady wind.
Both outflowing and inflowing currents are subject to the deflection towards the right imposed by the earth's rotation.
Bjerknes have been usefully applied in many cases, but they cannot take the place of direct observations of currents and of the fundamental processes and conditions underlying them.
The determination of the exact relationship of cause and effect in the origin of ocean currents is a matter of great practical importance.
In large mines where the air-ways are numerous and complicated, it often happens that currents travelling in opposite directions are brought together at one point.
The increased resistance, due to the large extension of workings from single pairs of shafts, the ventilating currents having often to travel several miles to the upcast, has led to great increase in the size and power of ventilating fans, and engines from 250 to Soo H.P. are not uncommonly used for such purposes.
When A is held still, and B rotated, centrifugal action sets up vortex currents in the water in the pockets; thus a continuous circulation is caused between B and A, and the consequent changes of momentum give rise to oblique reactions.
The warm currents setting landwards from the Indian Ocean bring both moisture and heat, so that the Swahili coast has a higher temperature and heavier rainfall than the Atlantic seaboard under the same parallels of latitude.
The currents in the bay make bathing dangerous.
It is supplied by the tidaland wind-formed currents, which are drifting sand from the Long Island and New Jersey coasts, extending the barrier beaches, such as Sandy Hook, out across the entrance to New York Bay.
Indeed even those first currents stand here for the deepest religious truths, the prevenience of God and man's affinity to Him.
A good many years later he was entrusted by the committee of the British Association on standards of electric resist ance with the task of deducing the mechanical equivalent of heat from the thermal effects of electric currents.
The current to be measured passes transversely across the disk and causes it to revolve in the magnetic field; at the same time the copper brake, geared on the same shaft, revolves in the field and has local or eddy currents produced in it which retard its action.
Induced or eddy currents are thus created in the copper disk, and the reaction of these against the magnetic field offers a resistance to the rotation of the disk.
Hence when a current is passed through the meter, the armature rotates and increases its speed until the driving force is balanced against the retarding force due to the eddy currents in the copper brake disk.
Below this pendulum let there be placed another coil through which passes the current to be measured; then when currents pass through these coils the pendulum of the second clock will be either accelerated or retarded relatively to the other clock, since the action of gravity is supplemented by that of an electric attraction or repulsion between the coils.
In this form it has the advantage that it can be used for either continuous or alternating currents.
It consists of a disk of aluminium, the axis of which is geared to a counting mechanism and which runs between the poles of permanent magnets that create eddy currents in it and therefore exert a retarding force.
Since the eddy currents induced in the disk are 90 degrees in phase behind the inducing field, the eddy currents produced by the main coil are in step with the magnetic field due to the shunt coil, and hence the disk is driven round by the revolution due to the action of the shunt coil upon the induced currents in the disk.
Hence the disk will be accelerated until the driving force is balanced by the retarding force due to the induced currents created in the disk by the permanent magnets.
The meter is made up also in a form suitable for use with two or three fixed electric currents.
But no uniform system of selection was pursued; or rather perhaps the results of several systems, adopted at various epochs, and under the influence of varying currents of ideas, became amalgamated in the final series.
It is true that the theory of vortex rings in hydrodynamics is of a simpler type; but electric currents cannot be likened to permanent vortex rings, because their circuits can be broken and the element of cyclic steadiness on which the simplicity depends is thereby destroyed.
Opposite the southern part of the town, where the currents have again united, the river is crossed by a suspension bridge, which at the time of its erection (1848-1853) was the largest enterprise of the kind in Europe.
The surface currents of the Pacific have not been studied in the same detail as those of the Atlantic, and their seasonal variations Circulation are little known except in the monsoon regions.
Those plants which are widely distributed are generally found to be propagated from seeds which can easily be carried by the wind or by ocean currents, or form the food of migratory birds.
When the currents flow through the two coils, forces are brought into action compelling the coils to set their axes in the same direction, and these forces can be opposed by another torque due to the control of a spiral spring regulated by moving a torsion head on the instrument.
The torque required to hold the coils in their normal position is proportional to the mean value of the product of the currents flowing through two coils respectively, or to the mean value of the product of the current in the power-absorbing circuit and the potential difference at its ends, that is, to the power taken up by the circuit.
If these conditions are not fulfilled, the wattmeter readings, assuming the wattmeter to have been calibrated with continuous currents, may be either too high or too low when alternating currents are being used.
The framework and case of the instrument must be completely non-metallic, else eddy currents induced in the supports will cause disturbing forces to act upon the movable coil.
Nearly all the Gulf coast rivers, however, are obstructed by bars owing to the quantity of silt brought down from the sierras and the prevailing winds and currents on the coast.
The headwaters of the rivers are for the most part mountain streams or elevated lakes; farther on their swift and winding currents - flowing sometimes between wide intervales, sometimes between rocky banks - are marked by numerous falls and fed by lakes.
The fleet now stood in to a bay called by the explorers Streamfiord or Firth of Currents, and wintered there (1003-1004), suffering some privations, and apparently getting no more news of the fruitful country desired.
Hot wire voltmeters, like electrostatic voltmeters, are suitable for use with alternating currents of any frequency as well as with continuous currents, since their indications depend upon the heating power of the current, which is proportional to the square of the current and therefore to the square of the difference of potential between the terminals.
This measurement is applicable to the measurement of high potentials, either alternating or continuous, provided that in the case of alternating currents the high resistance employed is wound non-inductively and an electrostatic voltmeter is used.
This last point is important in connexion with voltmeters used on the switchboards of electric generating stations, where relatively strong electric or magnetic fields may be present, due to strong currents passing through conductors near or on the board.
The tidal currents, or races, or roost (as some of them are called locally, from the Icelandic) off many of the isles run with enormous velocity, and whirlpools are of frequent occurrence, and strong enough at times to prove a source of danger to small craft.
The paired ctenidia are very greatly developed right and left of the elongated body, and form the most prominent organ of the group. Their function is chiefly not respiratory but nutritive, since it is by the currents produced by their ciliated surface that food-particles are brought to the feebly-developed mouth and buccal cavity.
Such a subdivision of the pallial chamber, and direction of the currents set up within it do not exist in a number of Lamellibranchs which have the gill-lamellae comparatively free (Mytilus, Arca, Trigonia, &c.), and it is in these forms that FIG.17.
The name "Kurile" is derived from the Russian kurit (to smoke), in allusion to the active volcanic character of the group. The dense fogs that envelop these islands, and the violence of the currents in their vicinity, have greatly hindered exploration, so that little is known of their physiography.
One of the most important industrial enterprises in the city is the electric plant belonging to the Rio de Janeiro Light and Power Company, which supplies electric currents for public and private lighting, and power for the tramways and many industries.
The causes which produce it are not well known, but it is generally attributable to currents of cold and damp air, to the use of wet leaves in feeding, and to sudden changes of temperature.
Barrier and fringing reefs, as well as atolls, occur in the group, but the channels between the islands are dangerous chiefly from the strong currents which set through them.
It is even true to say that an ambassador is practically debarred from coming into actual touch with currents of public feeling and the passing influences which, in this age of democracy, determine the course of events in the political life of peoples.
But the beautiful currents, but in the higher region shown by the hydrogen photographs the distribution of the dark flocculi suggested the operation of definite forces, though their nature remained obscure until the spring of 1908.
We must now go on to the crowning discovery of the induction of electric currents.
During his first period of discovery, besides the induction of electric currents, Faraday established the identity of the electrification produced in different ways; the law of the definite electrolytic action of the current; and the fact, upon which he laid great stress, that every unit of positive electrification is related in a definite manner to a unit of negative electrification, so that it is impossible to produce what Faraday called "an absolute charge of electricity" of one kind not related to an equal charge of the opposite kind.
The case of electro-magnetic forces between two conductors carrying electric currents affords an example of a statement of motion in terms of force of a highly artificial kind.
On the other hand, in winter the warm currents coming in from the Persian Gulf being met to a large extent by northerly currents from the snow-covered tracts of Armenia, are condensed down on to the plain and discharge moisture enough to cover the gravel steppes with spring herbage.
The prevailing winds are westerly, but they are frequently interrupted by warm breezes from the south, or moisture-bearing currents from the east.
All travellers testify to the perpetual wind currents from the west, which sweep across the salt bogs of Tsaidam (9500 ft.) and through the higher valleys of eastern Tibet.
Fearless and patient navigators, they ventured into regions where no one else dared to go, and, always with an eye to their monopoly, they carefully guarded the secrets of their trade routes and discoveries, and their knowledge of winds and currents.
It was soon discovered that the faculty of inducing dissociation possessed by the current might now be utilized with some hope of pecuniary success, but as electrolytic currents are of lower voltage than those required in electric furnaces, molten alumina again became impossible.
But in many parts deep transverse valleys intersect the prevailing direction of the ridges, and facilitate the passage of man, plants and animals, as well as of currents of air which mitigate the contrast that would otherwise be found between the climates of the opposite slopes.
In such an exploration of the sun's atmosphere it might be anticipated that definite currents, or some evidences of atmospheric circulation analogous to those familiar in terrestrial meteorology, would be discovered.
As waterways all the rivers labour under the drawbacks of rapids, mud-banks at their mouths, banks overgrown with forest, sparse population, and currents liable to serious variations due to irregularity of supply from the mountains and sudden rainfalls.
As regards their geographical distribution, fungi, like flowering plants, have no doubt their centres of origin and of dispersal; but we must not forget that every exchange of wood, wheat, fruits, plants, animals, or other commodities involves transmission of fungi from one country to another; while the migrations of birds and other animals, currents of air and water, and so forth, are particularly efficacious in transmitting these minute organisms. Against this, of course, it may be argued that parasitic forms can only go where their hosts grow, as is proved to be the case by records concerning the introduction of Puccinia malvacearum, Peronospora viticola, Hemileia vastatrix, &c. Some fungi - e.g.
As a result convection currents are produced in the air which are sufficient to catch the basidiospores in their fall and carry them, away from the regions of comparative atmospheric stillness near the ground, to the upper air where more powerful air-currents can bring about their wide distribution.
Thus the apparatus is analogous to the common transformers used for inducing from currents of great electromotive force and small quantity, which carry energy through long distances, currents of great quantity and small electromotive force for incandescent lights and for welding.
We thus have at the beginning of the Iron age two distinct currents of civilization in central Italy, the Latin and that of Villanova.
But about half a mile below Geneva this limpidity is disturbed by the pouring in of the turbid torrent of the Arve (left), descending from the glaciers of the Mont Blanc range, the two currents for some distance refusing to mix.
The currents of the Caspian were investigated by the Knipovich expedition; it detected two of special prominence, a south-going current along the west shore and a north-going current along the east shore.
After this it rose rapidly into importance as a manufacturing and commercial town, becoming, after Nuremberg, the centre of the trade between Italy and the north of Europe; its merchant princes, the Fuggers and Welsers, rivalled the Medici of Florence; but the alterations produced in the currents of trade by the discoveries of the 15th and 16th centuries occasioned a great decline.
Stagnation of water is inimical to the action of the roots, and does away with the advantageous processes of flowing and percolating currents.
The art is now so well understood that, by careful attention to the currents, the expert warp farmer can temper his soil as he pleases.
A bright aurora visible over a large part of Europe seems always accompanied by a magnetic storm and earth currents, and the largest magnetic storms and the most conspicuous auroral displays have occurred simultaneously.
The behaviour of the needle, as Paulsen points out, is exactly what it should be if the space occupied by the auroral curtain were traversed by electric currents directed upwards from the ground.
Birkeland (19), who has made a special study of magnetic disturbances in the Arctic, proceeding on the hypothesis that they arise from electric currents in the atmosphere, and who has thence attempted to deduce the position and intensity of these currents, asserts that whilst in the case of many storms the data were insufficient, when it was possible to fix the position of the mean line of flow of the hypothetical current relatively to an auroral arc, he invariably found the directions coincident or nearly so.
Composed of a congeries of nationalities which included Czechs, Magyars, Ruthenes, Rumanians, Germans, Italians, Flemings and other races, and with territories separated by many miles, the Habsburg dominions required from their ruler patience, tolerance, administrative skill and a full knowledge of the currents of European diplomacy.
These grooves doubtless serve to direct currents of water, carrying with them small organisms towards the mouth.
The currents induced in the coil are led to a dead-beat D'Arsonval galvanometer having the same natural period of vibration as the pendulum.
It can be demonstrated that they are practically indefatigable - repeatedly stimulated by electrical currents, even through many hours, they, unlike muscle, continue to respond with unimpaired reaction.
Sections of the Missouri flood plain made by the United States geological survey show a great variety of material of varying coarseness, the stream bed being scoured at one place, and filled at another by currents and floods of varying swiftness, so that sometimes the deposits are of coarse gravel, sometimes of fine sand, or of fine silt, and it is probable that any section of such an alluvial plain would show deposits of a similar character.
It used to be doubted whether these people could have gone from the Indian archipelago so far eastward, because the prevailing winds and currents are from the east.
Dwellings require careful construction, with thick walls and roofs of non-conducting material to keep out the heat-rays, and fans and punkahs are essential for the promotion of currents of air in the inhabited rooms. Personal protection, in the shape of thick pith topees, or cork helmets, and spinal pads, is necessary in the hot months, the clothing being light and loose and not too thin.
To a certain extent they have passed under the same succession of influences; they have been subjected to the same invasions, and have received accessions to their populations from the same currents of migration or conquest.
By the use of a revolving mirror similar to that used by Sir Charles Wheatstone for measuring the rapidity of electric currents, he was enabled in 1850 to demonstrate the greater velocity of light in air than in water, and to establish that the velocity of light in different media is inversely as the refractive indices of the media.
In Se p tember of that year he discovered that the force required for the rotation of a copper disk becomes greater when it is made to rotate with its rim between the poles of a magnet, the disk at the same time becoming heated by the eddy or "Foucault currents" induced in its metal.
The fact that the southern extremity of South America is the only land extending into this belt gives it special physical importance in relation to tides and currents, and its position with reference to the Antarctic Ocean and continent makes it convenient to regard it as a separate ocean from which the Atlantic, Pacific and Indian Oceans may be said to radiate.
Ferguson has shown that the sediment is carried away from this area by the set of the currents; probably then it has remained free from sediment whilst the neighbouring sea bottom has gradually been filled up. If so, the thickness of the alluvium is at least 1800 ft., and may be much more.
For the origin of the monsoon currents and their distribution see Monsoon.
The south-west monsoon currents usually set in during the first fortnight of June on the Bombay and Bengal coasts, and give more The or less general rain in every part of India during the next three months.
But the greater part of north-west India is served as a rule by cyclonic storms between the two currents.
His most valuable works include the Bengal Atlas (1779), the first approximately correct map of India (1783), the Geographical System of Herodotus (1800), the Comparative Geography of Western Asia (1831), and important studies on the geography of northern Africa - in introductions to the Travels of Mungo Park and Hornemann - and the currents of the Atlantic and Indian Oceans.
The coefficient of heating of a calorimeter when it is below the temperature of its surroundings is seldom, if ever, the same as the coefficient of cooling at the higher temperature, since the convection currents, which do most of the heating or cooling, are rarely symmetrical in the two cases, and moreover, the duration of the two stages is seldom the same.
It depends on the rapidity with which convection currents can supply heat from the interior to replace that radiated, and on a number of other nicely balanced circumstances which cannot well be calculated.
The chief natural features of the province are thus determined by the main streams, whose alluvial deposits first formed the central portion of the United Provinces; while the currents afterwards cut deep channels through the detritus they brought down from the ring of hills or uplands.
It is also exposed to the dangerous Papagayos tornadoes, caused by the prevailing north-easterly winds meeting opposite currents from the Pacific. It is drained on the south by the San Juan river, which flows generally east by south to the Caribbean Sea.
They have a sort of chart, medo, of small sticks tied together, representing the positions of islands and the directions of the winds and currents.
The developing eggs are not carried about by the mother, but deposited in her subaqueous burrow, "where they are aerated by the currents of water produced by the abdominal feet of the parent."
Exact statistics of the membership of the Churches of the Oriental rite are almost impossible to obtain; the numbers of their adherents, moreover, are apt to vary suddenly with the shifting currents of political forces in the East, for political factors have always played a considerable part in these movements towards reunion or the reverse.
His regular visits to Oxford kept him in intercourse with his old friends in Oriel common room, and made him familiar with the currents of feeling which swayed the university.
Elsewhere the surface movements at least are controlled by the prevailing winds, which give rise in places to complex "transverse" currents, and near the coast are modified by the channels enclosed by the coral reefs.
The zoological collections of the "Pola" expeditions show that certain well-defined districts are extremely rich in plankton, while others are correspondingly poor; and it appears that the latter occur in districts surrounded by currents of relatively low temperature, while the richer parts are where the movements of water are blocked by irregularities in the coast-line.
Their presence is due to lateral outgrowths of crystals shooting from the side of a growing stalactite, or to deflections caused by currents of air, or to the existence of a diminutive fungus peculiar to the locality and designated from its habitat Mucor stalactitis.
The two great branches of electrical theory which concern the phenomena of electricity at rest, or " frictional " or " static " electricity, and of electricity in motion, or electric currents, are treated in two separate articles, Electrostatics and Electrokinetics.
The second dates from Volta's discovery to the discovery by Faraday in 1831 of the induction of electric currents and the creation of currents by the motion of conductors in magnetic fields, which initiated the era of modern electrotechnics.
Arago's previous investigations in the new science of electromagnetism, and crowned that labour by the announcement of his great discovery of the dynamical action between conductors conveying the electric currents.
Ampere in this paper gave an account of his discovery that conductors conveying electric currents exercise a mutual attraction or repulsion on one another, currents flowing in the same direction in parallel conductors attracting, and those in opposite directions repelling.
These investigations led him to the announcement of the fundamental law of action between elements of current, or currents in infinitely short lengths of linear conductors, upon one another at a distance; summed up in compact expression this law states that the action is proportional to the product of the current strengths of the two elements, and the lengths of the two elements, and inversely proportional to the square of the distance between the two elements, and also directly proportional to a function of the angles which the line joining the elements makes with the directions of the two elements respectively.
Ampere had already previously shown that a spiral conductor or solenoid when traversed by an electric current possesses magnetic polarity, and that two such solenoids act upon one another when traversed by electric currents as if they were magnets.
These advances all centre round his supreme discovery of the induction of electric currents.
He found that at the moment the current in the battery circuit was started or stopped, transitory currents appeared in the galvanometer circuit in opposite directions.
All the space round magnets, currents and electric charges was therefore to Faraday the seat of corresponding lines of magnetic or electric force.
He proved by systematic experiments that the electromotive forces set up in conductors by their motions in magnetic fields or by the induction of other currents in the field were due to the secondary conductor cutting lines of magnetic force.
Kirchhoff determined experimentally in a certain case the absolute value of the current induced by one circuit in another, and in the same year Erik Edland (1819-1888) made a series of careful experiments on the induction of electric currents which further established received theories.
By this simple device he provided a means of measuring small electric currents far in advance of anything yet accomplished, and this instrument proved not only most useful in pure scientific researches, but at the same time was of the utmost value in connexion with submarine telegraphy.
The fundamental fact connecting electric currents and magnetic fields is that the line integral of magnetic force taken once round a conductor conveying an electric current is equal to 4 7r-times the surface integral of the current density, or to 4 7r-times the total current flowing through the closed line round which the integral is taken (see Electrokinetics).
In 1883 Lucien Gaulard, following a line of thought opened by Jablochkov, proposed to employ high pressure alternating currents for electric distributions over wide areas by means of transformers.
He also made great additions to the theory of alternating electric currents, and provided fresh appliances for other electrical measurements (see his Collected Scientific Papers, Cambridge, 1900) .
When two or more jets were used side by side the deposit was good opposite the centre of each, but bad at the point where two currents met, because the rate of flow was reduced.
As the freshets begin to lessen and retire into the deeper channels, the currents form natural embankments on their edges, preventing the return of a small portion of water which is thus left stagnant on the sands, and exposed to the action of the sun's rays.
An instrument of this form is valuable in measuring small alternating currents by the fall of potential produced down a known resistance.
Among the marine productions on the southern coast, a species of kelp, Macrocystis pyrifera, merits special mention because of its extraordinary length, its habit of clinging to the rocks in strong currents and turbulent seas, and its being a shelter for innumerable species of marine animals.
Unoccupied territory may, however, be prepared for the reception of new beds, by spreading sand, gravel and shells over muddy bottoms, or, indeed, beds may be kept up in locations for permanent natural beds, by putting down mature oysters and cultch just before the time of breeding, thus giving the young a chance to fix themselves before the currents and enemies have had time to accomplish much in the way of destruction.
The Cape peninsula and the western coast receive the cold currents from the Antarctic regions.
Diurnal currents of wind, which are established from the plains to the mountains during the day, and from the hills to the plains during the night, are impqrtant agents in distributing the rainfall.
The condensation of vapour from the ascending currents and their gradual exhaustion as they are precipitated on successive ranges is very obvious in the cloud effects produced during the monsoon, the southern or windward face of each range being clothed day after day with a white crest of cloud whilst the northern slopes are often left entirely free.
Once assume that every character and property of a particular thing is determined solely by the tension in it of a current of Pneuma, and (since that which causes currents in the thing cannot be absolutely the same with the thing itself) Pneuma, though present in all things, must be asserted to vary indefinitely in quantity and intensity.
What really is - the Pneuma - neither increases nor diminishes; but its modes of working, its different currents, can be conveniently distinguished and enumerated as evidence of so many distinct attributes.
Its geographical position and history have rendered Portugal very dependent for intellectual stimulus and literary culture on foreign countries, and writers on Portuguese literature are wont to divide their subjects into periods corresponding to the literary currents from abroad which have modified its evolution.
If the vessel is deep, these currents will be balanced by counter currents below them, but if the depth of the water is only two or three millimetres, the surface-current will sweep away the whole of the water, leaving a dry spot where the alcohol was dropped in.
It is important to notice that Herbert, as English ambassador at Paris, united in himself the currents of French and English thought, and also that his De Veritate, published in Latin and translated into French, did not appear in an English version.
We see by means of the eye alone, and hear by means of the ear alone, these organs being best adapted to receive the images or sound currents.
The framework carrying the clamps is arranged so that a number of determinations may be made at one time, the wires from the clamps running from a rheostat, so arranged that currents of any strength may be used simultaneously.
In 1838 he made important investigations in regard to the conditions and range of induction from electrical currents - showing that induced currents, although merely momentary, produce still other or tertiary currents, and thus on through successive orders of induction, with alternating signs, and with reversed initial and terminal signs.
One of the earliest was devoted to electrical conduction in a thin plate, and especially in a circular one, and it also contained a theorem which enables the distribution of currents in a network of conductors to be ascertained.
Another discussed conduction in curved sheets; a third the distribution of electricity in two influencing spheres; a fourth the deter mination of the constant on which depends the intensity of induced currents; while others were devoted to Ohm's law, the motion of electricity in submarine cables, induced magnetism, &c. In other papers, again, various miscellaneous topics were treated - the thermal conductivity of iron, crystalline reflection and refraction, certain propositions in the thermodynamics of solution and vaporization, &c. An important part of his work was contained in his Vorlesungen fiber mathematische Physik (1876), in which the principles of dynamics, as well as various special problems, were treated in a somewhat novel and original manner.
Its horizontal movements, which ought to be the more important, are accidental movements due to air currents, and cannot be controlled; the balloon, in short, cannot be guided.
One might as well attempt to steer a boat carried along by currents of water in the absence of oars, sails and wind, as to steer a balloon carried along by currents of air.
Extensive inert surfaces indeed are contra-indicated in a flying machine, as they approximate it to the balloon, which, as has been shown, cannot maintain its position in the air if there are air currents.
A flying machine which could not face air currents would necessarily be a failure.
She regulates the surfaces to the strength and weight of the flying creature and the air currents to which the surfaces are to be exposed and upon which they are to operate.
These surfaces may be conferred on artificial wings, aeroplanes, aerial screws or similar structures; and these structures, if we may judge from what we find in nature, should be of moderate size and elastic. The power of the flying organs will be increased if they are driven at a comparatively high speed, and particularly if they are made to reverse and reciprocate, as in this case they will practically create the currents upon which they are destined to rise and advance.
They depended mainly on the utilization of natural air currents, trusting for stability and balance to movements in their own bodies, or in portions of their machines which they could control.
Throughout his work he gives a prominent place to everything which illustrates human progress in moral and religious, as well as political conceptions, and specially to the rise and development of the idea of religious toleration, finding his authorities not only in the words and actions of men of mark, but in the writings of more or less obscure pamphleteers, whose essays indicate currents in the tide of public opinion.
But he was almost unawares borne away by the mighty currents of the time, and he took part in the attacks on the monarchy, on the clergy, on church property, and on the provincial parlements.
It would never get established because currents would arise to exchange the positions of the hotter, less dense, inner parts and the cooler, more dense, outer ones.
Since the only cause for these convection currents is the statical instability produced by radiation, and the rapid stifling of radiations within the body produces there a temperature gradient falling very slowly, they would be for the most part extremely slight.
Indeed it seems that, in the final distribution of density throughout the part which is not subject to violent convection currents, it must increase slightly from the centre outwards, since the currents would cease altogether as soon as 'a uniform state was restored.
Currents setting towards the north or north-west have been observed in various parts of the lake.
Such modified zooids are called siphonozooids, their function being to drive currents of fluid through the canal-systems of the colonies to which they belong.
Some of these ancient seaweeds may have remained permanently rooted in the littoral regions, while others may have become broken off and drifted, like the recent Sargassum, at the mercy of the winds and currents, carrying the attached Graptolites into all latitudes.
In severe storms the water near shore is filled with sand, which is deposited where the currents are checked around the ends of jetties in such a way as to form bars out into the lake across improved channels.
There are no tides, and usually only a slight current towards the outlet, though powerful currents are temporarily produced by the rapid return of waters after a storm, and during the height of a westerly gale there is invariably a reflex current into the west end of the lake.
North of the equator the surface circulation is under the control of the monsoons, and changes with them, the currents consisting chiefly of north-east and south-west drifts in the open sea, and induced streams following the coasts.
When the main equatorial current reaches the African coast a minor stream is sent northwards to the source of the Indian counter-current, but the discharge is chiefly by the Mozambique current, which south of Cape Corrientes becomes the Agulhas current, one of the most powerful stream currents of the globe.
The west wind drift sends a stream northwards along the west coast of Australia, the West Australia current, the homologue of the Benguela current in the South Atlantic. The principal feature in the circulation in the depths of the Indian Ocean is a slow movement of Antarctic water northwards along the bottom to take the place of that removed from the surface by evaporation, and by currents in the lower latitudes.
Barred by reefs, and full of rapids and impetuous currents, it cannot become a commercial avenue.
It has its sources in the Guiana highlands, but its long course is frequently interrupted by violent currents, rocky barriers, and rapids.
Slow in their movements, and feeding on vegetable substances, they are confined to the neighbourhood of rivers, estuaries or coasts, although there is a possibility of accidental transport by currents across considerable distances.
In these waters a vertical circulation is kept up by convection currents.
These teleutospores remain inactive on the straw until spring, when they germinate in manure heaps or on moist ground and produce minute sporidia, which are conveyed by air currents to the alternate host, in this case a barberry.
The sea pierces the islands in deep fjords, or separates them by narrow inlets through which tidal currents set with great violence, at speeds up to seven or eight knots an hour; and, as communications are maintained almost wholly by boat, the natives have need of expert watermanship. There are several lakes in which trout are abundant, and char also occur; the largest is Sdrvaag Lake in Vaagd, which is close to the sea, and discharges into it by a sheer fall of about 160 ft.
Clerk Maxwell and George Chrystal that Ohm's law is true, within the limits of experimental error, even when the currents are so powerful as almost to fuse the conducting wire.
Of the two contrary currents which have continually mingled and conflicted throughout the course of French history, that of monarchic absolutism and that of aristocratic and democratic liberty, the former was now to carry all before it.
The revolution was already complete currents before it was declared to the world.
Two distinct of the currents of disaffection, one economic, the other R0h1 philosophic, had for long been pervading the nation.
But those in whom the two currents converged did not belong to the pure Arab race.
Ice forms over fresh water if the temperature of the air has been for a sufficient time at or below the freezing-point; but not until the whole mass of water has been cooled down to its point of maximum density, so that the subsequent cooling of the surface can give rise to no convection currents, is freezing possible.
The Loup system is remarkable for the even dip of its parallel feeders, which once joined the Platte separately, until the latter banked up its deposits across the mouths of their more sluggish currents.
The dynamical causes are atmospheric and oceanic currents.
Were these currents invariable their only effect would be that the Eulerian motion would not take place exactly round the mean pole of figure, but round a point slightly separated from it.
Currents from the ten-thousandth of an ampere to ten thousand amperes, electrical pressures from a minute fraction of a volt to 100,000 volts, come within the range of his instruments, while the private consumer of electric energy is provided with a meter recording Board of Trade units.
It breaks up into fragments, which become rounded by attrition, but after they reach a certain minuteness are borne along by currents of water or air in a state of suspension, and are not further reduced in size.
They are deposited where the currents are checked and the water becomes very still.
Above these are upper currents from the north or north-west.
The commingling of the two currents gives rise frequently to westerly and occasionally to easterly winds.
He laboured assiduously to obtain observations as to the winds and currents by distributing to captains of vessels specially prepared log-books; and in the course of nine years he had collected a sufficient number of logs to make two hundred manuscript volumes, each with about two thousand five hundred days' observations.
There should be complex interaction between those trends and currents.
But there were also reasons adduced that we would now regard as more plausible, based on currents and tides.
The running aground off Spain was due to fog and unpredictable currents.
Along with all the other waves and currents it detects, altimetry also reveals invisible waves.
Use function relays to conduct high amperage or alternate voltage currents.
About 60 million cubic meters of dome and crater wall traveled to the south as a debris avalanche and pyroclastic density currents.
But, please do not bathe here; the beach shelves sharply and the currents are very strong at the point.
These fields and currents are connected to and correlated with the EEG and ECG that are a routine part of conventional biomedicine.
With its gently shelving beaches and a warm air currents, the Algarve has drawn visitors to its sun-drenched shores for years.
All too often it has lost touch with wider intellectual currents.
Vortex Dynamics Dr. A.M. Campbell The project is investigating the role of surface currents in the critical current of BSCCO crystals.
The area is swept by strong tidal currents making this site a slack water dive.
Tides and currents The region consists of a deeper channel in the west, with shallower embayments in the east.
Yet, book guide travel travel like wireless currents, their flow eternally encircles the earth.
Burns caused by the passage of heavy currents through the body or by direct contact with an electrically heated surface.
Certain information included a glance at he passed currents Charles henry in.
He frequently clashed with Jean-Paul Sartre and others who combined Marxism with psychoanalysis, structuralism and other philosophical currents inherently incompatible with Marxism.
The comparatively low currents also make the inverter less sensitive to layout and stray inductance.
These are extremely handy for loads that have large inrush vs. operating currents.
The feedback process which destabilizes these irregularities is associated with the heating effect of parallel electron currents in the collisional lower ionosphere.
This experiment's goal is the observation of currents induced by a changing magnetic field.
The solar absorber is placed symmetrically at mid level in the solar collector and is abundantly perforated to allow upward air currents.
After hatching the larvae are carried by the currents and join other plankton.
The currents are arranged to be in phase quadrature.
Since then, Holocene sedimentation has been dominated by along slope transport by bottom currents.
A gentle purring rattles the air currents above the South Stand, but the stadium seems as sleepy as it's been for years.
Experimental currents in visual arts such as abstract expressionism were unfavorably compared with the soviet socialist realism.
Despite the strong currents, there is quite a collection of spiny spider crabs, pipefish, crabs and lobsters inside the caves.
The ITER-FEAT design has placed more emphasis on achieving a steady-state burn using non-inductive currents than the original ITER design.
Secondly, that the polymer tantalum type has higher leakage currents than traditional capacitors.
I joined NPL in June 1997 to work on applications of single-electron transistors in precise measurement of small electrical currents.
Can you uncover the truths traveling the currents of the River of Blood?
At ' the corner ' the currents pick up and the napoleon wrasse & eagle rays come out to play.
The exposed position of the bay, and the diversity of its currents, have rendered it notorious for its storms.
In the straits joining it with the Atlantic and the Black Sea the fresher surface waters of these seas flow inwards to assist in making good the loss by evaporation at the surface of the Mediterranean, and in both cases dense water makes its way outwards along the bottom of the channels, the outflowing currents being less in volume and delivery than the inflowing.
Holfmann, from observations on the amplitude of saturation currents, deduce q =4 as a mean value.
Though the islands are under the equator, the climate is not intensely hot, as it is tempered by cold currents from the Antarctic sea, which, having followed the coast of Peru as far as Cape; Blanco, bear off to the N.W.
Again, during the winter months pressure is relatively high over North America, Western Eurasia and the Arctic regions; hence vast quantities of air are brought down to the surface, and circulation must be kept up by ascending currents over the ocean.
In 1840 he showed that when an electric current was produced by means of a dynamo-magneto-electric machine the heat generated in the conductor, when no external work was done by the current, was the same as if the energy employed in producing the current had been converted into heat by friction, thus showing that electric currents conform to the principle of the conservation of energy, since energy can neither be created nor destroyed by them.
Extending his investigations to the currents produced by batteries, he found that the total voltaic heat generated in any circuit was proportional to the number of electrochemical equivalents electrolysed in each cell multiplied by the electromotive force of the battery.
By the action of the two variable currents on the electromagnetic mechanism in the receiver, the two component motions are reproduced and by their combined action on a second system of levers the receiving pen is caused to duplicate the motions of the transmitting pencil.
In these annular spaces there are suspended by springs two light coils of fine copper wire, capable of being moved vertically, and connected in such a manner as to be traversed by the two variable line currents from the transmitter.
As the earth is used for completing the electric circuit, the signals received on such sensitive instruments as these are liable to be disturbed by the return currents of other systems in their immediate neighbourhood, which also use the earth as return, when such are of the magnitude generated by the working of electric tramways FIG.
The explanation of the action of the shunt is that all slowly varying currents affect the coil of the receiving instrument and its shunt in inverse proportion to their respective resistances; whereas with the comparatively rapid variations of current used in signalling the coil is forced at the beginning of each element of A v
For nearly a week futile attempts were made to send messages by his methods, and then a return was made to the weak currents and the mirror galvanometers of Sir William Thomson (Lord Kelvin) which had been employed for testing purposes while the cable was being laid.
A very ingenious call-bell arrangement was devised, capable of responding only to regularly reversed battery currents, but not 1 See Fahie, History of Wireless Telegraphy, p. 170; also 5th Report (1897) of the Royal Commission on Electrical Communication with Lightships and Lighthouses.
The electromotive force of the coil is, however, great enough to create in these air gaps displacement currents which are of magnitude sufficient to be equivalent to the conduction current required to actuate a telephone.
It was seen that the effect of the impact of the incident electric waves upon the vertical receiving wire was to create in it electrical oscillations, or in other words, high frequency alternating electric currents, such that whilst the potential variations were a maximum at the top or insulated end of the antenna the current at that point was zero and at the base the potential variation was zero and the current amplitude a maximum.
Fleming devised a method which has practical advantages in both preventing the arc and permitting the oscillatory currents to be controlled so as to make electric wave signals.
In addition to the above gaseous rectifiers of oscillations it has been found that several crystals, such as carborundum (carbide of silicon), hessite, anastase and many others possess a unilateral conductivity and enable us to rectify trains of oscillations into continuous currents which can affect a telephone.
Hence, when the undulating telephonic currents were made to pass through the apparatus, the constant variation of the friction of the spring caused the deflexions of the diaphragm to vary in unison with the variation of the electric The extreme smallness of the magnets which might be successfully employed was first demonstrated by Professor Peirce of Brown University, Providence, R.I.
This takes account of - (I) the ArcticAlpine zone, including all the vegetation of the region bordering on perpetual snow; (2) the Boreal zone, including the temperate lands of North America, Europe and Asia, all of which are substantially alike in botanical character; (3) the Tropical zone, divided sharply into (a) the tropical zone of the New World, and (b) the tropical zone of the Old World, the forms of which differ in a significant degree; (4) the Austral zone, comprising all continental land south of the equator, and sharply divided into three regions the floras of which are strikingly distinct - (a) South American, (b) South African and (c) Australian; (5) the Oceanic, comprising all oceanic islands, the flora of which consists exclusively of forms whose seeds could be drifted undestroyed by ocean currents or carried by birds.
A staunch Roman Catholic, but belonging to a school of Augustinian enthusiasts (the Jansenists), whom the Church put down as heretics, he stands pretty much apart from the general currents.
The heat makes itself evident by raising the temperature and therefore elongating the wire, whilst the magnetic field creates mechanical forces which act on pieces of iron or other conductors conveying electric currents when placed in proximity to the conductor in question.
The instrument can be calibrated by continuous currents and may then be used for high frequency alternating currents.
Instruments of this type with a permanent magnetic field are only available for the measurement of continuous currents, but soft-iron instruments of II??II?NIIIiIC?p u??i?,,.
He had compiled a sea-atlas (the Bahrije) of the Aegean and Mediterranean seas, every nook and cranny of which he had explored, with an account of the currents, soundings, landing-places, inlets and harbours.
Now it is probable that the main cause of oceanic circulation is the driving force of the winds upon the superficial layers of water; hence periodic and irregular changes in the direction and velocities of ocean currents are probably due to changes in atmospheric circulation traceable to changes in the quantities of heat absorbed from the sun by the earth's atmosphere.
Fleming, Magnets and Electric Currents (London, 1898); C. Maurain, Le magnetisme du fer (Paris, 1899; a lucid summary of the principal facts and laws, with special regard to their practical application); Rapports presentes au Congrks international de physique, vol.
Aime estimated this depth at 150-200 fathoms, while the observations of the Austrian expedition in the eastern Mediterranean found it to be from 200 to nearly 400 fathoms. In the Red Sea, where a similar seasonal change occurs, the depth to which the surface layer warms up is about 275 fathoms. The great difference in salinity between the surface and the deep water excludes the possibility of effective convection in the seas of northern Europe, and in the open ocean the currents which are felt everywhere, and especially those with a vertical component, must exercise a very disturbing influence on convection.
When these last coils are traversed by an alternating current they induce local or eddy currents in the disk.
Hagen that for dark heat rays of only about ten times the wave-length of luminous radiation, the properties of metals are determined by their electric resistance alone, which then masks all resonance due to periods of free vibration of the molecules; and, moreover, that the resistance for such alternations is practically the same as the ohmic resistance for ordinary steady currents.
Again the shunt circuit must have practically zero inductance and the series or current coil must be wound or constructed with stranded copper wire, each strand being silk Covered, to prevent the production of eddy currents in the mass of the conductor.
If placed upon Europe it would extend from Rome to the North Cape, but latitude is of course only one of the factors influencing climate, the arrangement of the ocean currents and of the areas of high and low pressure making a very wide difference between the climates of the two sides of the Atlantic. In reality the Pacific coast of Canada, rather than the Atlantic coast, should be compared with western Europe, the south-west corner of British Columbia, in lat.
That the condition of gaping of the shell-valves is essential to the life of the Lamellibranch appears from the fact that food to nourish it, water to aerate its blood, and spermatozoa to fertilize its eggs, are all introduced into this gaping chamber by currents of water, set going by the highlydeveloped ctenidia.
As in Europe, these northern peoples will hold the power which intelligent democracies are consciously absorbing, and the British faculty for statecraft is gradually welding new nations on the British model, without the obsolete traditions and without that human sediment which too frequently chokes the currents of national vitality in the older communities of Europe.
At higher pressures the effect of conduction was masked by convection currents.
Leyden jars are now much employed for the production of the high frequency electric currents used in wireless telegraphy (see Telegraphy, Wireless).
The French mathematicians, Coulomb, Biot, Poisson and Ampere, had been content to accept the fact that electric charges or currents in conductors could exert forces on other charges or conductors at a distance without inquiring into the means by which this action at a distance was produced.
But the fry drift with the currents as helplessly as the eggs, and the a priori objections to the utility of the operations have in no case been met by evidence of tangible results.
In these waters a vertical circulation is kept up by convection 287 currents.
Strong currents and heavy sediment had quickly covered the wreckage removing all traces of the flight recorders.
Local deposition of rippled sands on the lower slope suggests peak currents in the order of 30-40 cms -1.
Swift currents flowing between the Atlantic and the North Sea soon eroded the islands, leaving the stumps as sandbanks in the channel.
The changing nature of electrical installations is reducing their natural impedance, so that higher short-circuit currents occur.
Pink pebbles are carried by strong currents from broken slabs incised by ice.
A gentle purring rattles the air currents above the South Stand, but the stadium seems as sleepy as it 's been for years.
Experimental currents in visual arts such as abstract expressionism were unfavorably compared with the Soviet socialist realism.
An additional feature is that much higher currents can flow through some superconductor materials than through normal metal wires.
In addition, saturation currents have a built-in temperature dependence.
The built in balun provides a truly unbalanced input and prevents any RF currents traveling down the outer of the feeder cable.
The truly unbalanced input prevents any RF currents traveling down the outer of the feeder cable.
In Chile we visited the coastal desert with its oases and its nutrient-rich upwelling sea currents.
Unfortunately, it's hard to control a wide kayak if you hit rapids or fast currents.
Traditional grenadine syrup was sometimes made with black currents and pomegranates.
Turbine blades turn in several parts of the country, generating power from the wind currents that flow across the Earth as a direct result of the uneven heating of the planet as it orbits the sun.
As the temperature of the surface waters at the poles increases the circulation of the currents will slow.
Sailing ships invite guests to step back in time and experience a true cruising sensation under the powers of currents, tides, and wind.
Larger ships are less affected by the ocean's waves and cross currents, lessening the possibility of seasickness for many individuals.
In the wild the seahorse uses its tail to hold onto seaweed to stop itself from getting swept away by currents.
For example, the ocean poses dangers of riptides, unexpected high waves and currents while a lakeside beach may pose health dangers from bacteria in the water or possible injury from diving into unknown shallow water.
Radiofrequency palatoplasty uses electrical currents to shrink the uvula and the soft palate.
The Zuni River circles much of the park and features lazy curves and gently currents to enjoy, while the nearby wave pool offers more exciting splashes for everyone.
Electrical currents give off heat, so depending on the flow of the current the heat conducted by the electrical current is either absorbed or released.
The koi fish has a powerful and energetic life force, demonstrated by its ability to swim against currents and even travel upstream.
Alcatraz with its isolation, treacherous currents, and chilly waters made it ideal to house these worst of the worst criminals.
They called it the "bridge that couldn't be built" due to the foggy weather, 60 mile per hour winds and strong ocean currents.
To get the best results with the Glade Wisp, it should be placed in an area that has gentle air currents to help disperse each wisp of scent.
Any idea why the currents run the direction they do in the lake?
She trotted to the spot she'd identified from the tree as being where the currents appeared to originate from.
This will be composed of a conduction and a convection current, the latter due to rising or falling air currents carrying ions.
This is insignificant compared to the size of the currents which several authorities have calculated from considerations as to terrestrial magnetism.
Wilson considers that convection currents in the upper atmosphere would be quite inadequate, but conduction may, he thinks, be sufficient alone.
Of late years many experiments have been made on the influence of electric fields or currents on plant growth.
The trade winds give rise, in the region most exposed to their influence, to two westward-moving drifts - the equatorial currents, which are separated in parts of their course by currents moving in the opposite direction along the equatorial belt.
These last may be of the nature of " reaction " currents; they are collectively known as the equatorial counter-current.
Suppose the arm c of the switch S to be in contact with 2; thin when the key is manipulated it sends alternately positive and negative currents into the line.
In order that the line between two stations may be worked on the duplex system it is essential that the receiving instrument shall not be acted on by the outgoing currents, but shall respond to incoming currents.
Now if the values of the rheostat and condenser are adjusted so as to make the rise and fall of the outgoing current through both windings of the relay exactly equal, then no effect is produced on the armature of the relay, as the two currents neutralize each other's magnetizing effect.
Incoming currents pass from line through one coil of the relay, the key, and either the battery or battery resistance, according as whether the key is raised or depressed.
The result is that the armature of the relay is attracted, and currents are sent through the sounder from the local battery, producing the signals from the distant station.
This arrangement can be duplexed in the way already explained, by providing differential relays and arranging for the outgoing currents to divide differentially through the two relays at each end.
A ray of light is directed upon the mirror, and the motion of the latter, due to the varying strengths and direction of the received currents, is made to write the transmitted signals upon a strip of bromide photographic paper about three inches wide.
In the Rowland multiple method of telegraphic working, the transmitter consists of a mechanical keyboard provided with a series of levers, which effect certain combinations of positive and negative currents for each letter.
These currents are furnished by an alternator which transmits sine currents over the line and operates a motor at the distant end of the line, both machines running in synchronism.
Each transmitter is therefore able to transmit a separate series of positive and negative currents in different combinations; these are distributed, by suitably arranged distributors and relays at the receiving end of the line, into their respective receivers.
The function of the " combiner " in each receiving instrument is so to group the received combination of positive and negative currents that they operate polarized relays in such a manner that the position of the tongues corresponds with the operation of the levers on the transmitter.
The motion communicated to rollers by the pencil serves to cut resistance in or out of the two line circuits which are connected to the rollers, and thus two independent variable line currents are obtained.
A modification (known as the cable code) of the ordinary single needle alphabet is used; that is to say, currents in one direction indicate dots and in the other direction dashes.
To detect these currents some device has to be inserted in the antenna circuit or else inductively connected with it which is sensitive to high frequency currents.
These currents vary in speed from 4 to so m.
Though scepticism as a definite school may be said to date only from the time of Pyrrho (q.v.) of Elis, the main currents of Sophistic thought were sceptical in the wider sense of that term.
He instinctively recognized not only the vital necessity of the maintenance of the union between the two states, but also the fact that the chief source of danger to the union lay Gas;m11 IV., g y in Lithuania, in those days a maelstrom of conflicting political currents.
The trochus forms the powerful currents for locomotion, and for the supply of food material, while the cingulum produces a local current round the upper rim of the corona to bring the food particles direct to the mouth, which is displaced through a postero-ventral gap in the trochus to lie behind the disk, just as occurs in the more specialized Ciliata.
In the marsupials it is more evident, and its excitation by electric currents evokes movements in the musculature of the crossed side of the body.
The currents thus divide at instrument as in Frischen's method, two resistances the point D, and it is clear that if the difference of potential between P and Q is unaffected by closing the sending key, then no change of current will take place in the instrument circuit.
Should the rotating arms fail to pass over these correcting segments at their synchronous positions, correcting currents pass to a relay which cuts off momentarily the current actuating the tuning-fork, thereby altering the rate of vibration of the latter until the arms once more run together uniformly.
She noticed the currents then climbed a tree and said they were moving in a pattern around the lake.
Elsewhere local surface currents are developed, either drifts due to the direct action of the winds, or streams produced by wind action heaping water up against the land; but these nowhere rise to the dignity of a distinct current system, although they are often sufficient to obliterate the feeble tidal action characteristic of the Mediterranean.
Wilson supposes that by the fall to the ground of a preponderance of negatively charged rain the air above the shower has a higher positive potential than elsewhere at the same level, thus leading to large conduction currents laterally in the highly conducting upper layers.
The tendency of the currents in the Channel opposite Brighton is to drive the shingle eastward, and encroachments of the sea were frequent and serious until the erection of a massive sea-wall, begun about 1830, 60 ft.
The movements of the northern branch of the Gulf Stream drift have been the object of more careful and more extended study than all the other currents of the ocean put together, except, perhaps, the Gulf Stream itself.
Where surface water is banked up against the land, as by the equatorial and Gulf Stream drift currents, it appears to penetrate to very considerable depths; the escaping stream currents are at first of great vertical thickness and part of the water at their sources has a downward movement.
This, with proper apparatus for originating electric currents at one end and for discovering the effects produced by them at the other end, constitutes an electric telegraph.
If the looped lines are both in good condition and free from leakage, the current sent out on line r will be exactly equal to the current received back on line 2; and as these currents will have equal but opposite effects on the galvanometer needle, no deflection of the latter will be produced.
For working " double current," two sets of accumulators are provided, one set to send the positive and the other set the negative currents; that is to say, when, for example, a double current Morse key is pressed down it sends, say, a positive current from one set, but when it is allowed to rise to its normal position then a negative current is transmitted from the second set of accumulators.
The weight of the iron sheath varies greatly according to the depth of the water, the nature of the sea bottom, the prevalence of currents, and so on.
In this apparatus electric A B C currents are generated by turning a handle (placed in front of the instrument), which is geared, in the instru ment.
When one of a series of keys (each corresponding to a letter) arranged round a pointer is depressed, the motion of the pointer, which is geared to the shuttle armature, is arrested on coming opposite that particular key, and the transmission of the currents to line is stopped, though the armature itself can continue to rotate.
The currents actuate a ratchet-wheel mechanism at the receiving station, whereby the hand on a small dial is moved on letter by letter.
When the key is in the middle position, that is, not making connexion with either the front or back contacts, the received currents pass through both coils of the relay and the rheostat; no interference is, however, felt from this extra resistance because, although the current is halved, it has double the effect on the relay, because it passes through two coils instead of one.
Innumerable little streams overlap and interlace one with another, exhibiting a sort of hybrid product, which obeys half way the law of currents, and half way that of vegetation.
Deidre sought to figure out what it was about the currents and subtle movement that kept her in place when she wanted to return to the castle, where it was warm.
He beat the air mercilessly with his wings, rising high above the city and coasting on cold wind currents until he reached the ocean.
On Mountains Much Seems To Depend On Whether There Are Rising Or Falling Air Currents, And Results From A Single Season May Not Be Fairly Representative.
Hence for sending both a dot and a dash, reverse currents of short duration are sent through the line, but the interval between the reversal is three times as great for the dash as for the dot.
At regular intervals a rotating arm on the distributor connects the five keys of each keyboard to line, thus passing the signals to the distant station, where they pass through the distributor and certain relays which repeat the currents corresponding to the depressed keys and actuate electromagnets in the receivers.
It is true, we are such poor navigators that our thoughts, for the most part, stand off and on upon a harborless coast, are conversant only with the bights of the bays of poesy, or steer for the public ports of entry, and go into the dry docks of science, where they merely refit for this world, and no natural currents concur to individualize them.
The coolness of his touch turned to gentle electric currents that worked their paths through her skull.
The currents were produced by a magneto-electric machine resembling that of Clarke.
Since each letter is represented by a specific combination of positive and negative currents, it is possible, by means of the combinations, to close a local circuit at any given interval, and so cause the paper to be pressed against the periphery of the type-wheel at the time when the letter required is opposite.
The development of the equatorial and the Brazil currents in the South Atlantic has already been described.
The south-moving currents originating from melting ice are probably quite shallow.