The current balance owed was over four hundred dollars.
This is the current battle situation.
Since his current office was directly across from their bedroom, it seemed a better place for babies that Alex said could be born early.
She forced her mind back to the current issue.
These visions are totally verifiable in current time.
In spite of Rostopchin's broadsheets, or because of them or independently of them, the strangest and most contradictory rumors were current in the town.
Its thin current slides away, but eternity remains.
Solving a current murder was difficult enough—a forty-year-old case was near impossible.
They appeared more reasonable in his current state.
No documentation to current day activity was listed.
Then he added hesitantly, The paper said the current on the bay is strong.
She shivered, as much from the warm current working its way through her body as the cold ocean breeze.
The green gems were caught in some sort of invisible current that ended when it reached the bank.
With there being no current battle, there was nothing to test her.
A few floated away until caught by another current while others settled nearby.
The success of the restaurant rested more on out-of-date memories than the current excellence of its bill of fare.
If his family wanted him to come back, they would have to get rid of his current responsibilities.
"Business," his second-in-command and current lover said, seating herself.
His magic warmed her from the inside out, the gentle current spreading through her body the longer they remained in contact.
In other words, when he shook himself free of his current family, he would come to Dulce.
That's why more current dates are more important and far easier to verify.
Whether things in the future stay the same as they are today or change from what they are today, both are understood in terms of the current reality.
The current stopped, and she convulsed on the cold marble floor.
She told Katie that Alex was back, but said nothing about their current situation.
He'll be replacing Elise as your current roommate for the time being.
They may try to ban you from day trading given the current climate.
Current events—our present life—was all we wanted.
While the equipment didn't match what was displayed on the cover of current ski magazines, they looked surprisingly good for the twenty bucks Fred said he'd paid for them, with boots and poles part of the package.
YouTube's contribution to world peace is not simply to add empathy to current events, although that would be enough.
Its rapid current does not permit of extensive navigation, but timber rafts are floated down from above Innsbruck.
That necklace will absorb new magic and prevent him from accessing the depths of his current store.
When Paris was mentioned, Mademoiselle Bourienne for her part seized the opportunity of joining in the general current of recollections.
I figured this county deserves a more astute sheriff than the current candidate, so I tossed my hat in the ring this morning.
Kris's features clouded, and Gabriel suspected it was because Kris had been with his current lover, Jade, for hundreds of years.
However, when the phone rang—one a reservation, the other a lengthy call for Fred from his current beloved—Cynthia jumped like a startled rabbit.
Then it occurred to me that it was useless to continue the struggle--I must do something to turn the current of her thoughts.
Metallic cobalt may be obtained by reduction of the oxide or chloride in a current of hydrogen at a red heat, or by heating the oxalate, under a layer of powdered glass.
When Carmen asked if she had more current pictures of her family, Katie grew sullen.
The raft had long since stopped and only the waves of the current beat softly against it below.
Dorothy and the buggy had floated slowly down stream with the current of the water, and the others made haste to join her.
She was his current waltzing widow—first choice to fill his dance card when he wasn't surfing the net, tracking down an auction or garage sale or devouring a mystery novel.
She certainly shares our opinion that the current day Dawkins are a sorry lot.
Dean called the Parkside Police Department and caught hell from Leland for not keeping him posted on the Wasserman autopsy and current details.
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.
But what about a reasoned belief based on a balanced look at both history and current reality that leads you to be optimistic?
It's quite another to do so only because they are the current trend.
They were simply inquiring about the current ownership.
This here's the phone number of the current muck amuck.
From reports current in town she learned how the Rostovs were situated, and how "the son has sacrificed himself for his mother," as people were saying.
Quinn didn't have to record current time settings; he knew that stuff by heart.
Cobalt chloride, CoC1 2, in the anhydrous state, is formed by burning the metal in chlorine or by heating the sulphide in a current of the same gas.
So the current frustrating situation, where so many people have such wildly divergent understandings about nutrition, will fade away.
He gave an angry thrust to his horse, which had grown restive under him, and plunged into the water, heading for the deepest part where the current was swift.
What you loved about me is present in your current mate.
If he was in bed under the current circumstances, he must be sicker than he was letting on.
Heated at 190-300° in a current of hydrogen it gives the oxide C0304, while at higher temperatures the monoxide is formed, and ultimately cobalt is obtained.
Cobalt monoxide, CoO, is prepared by heating the hydroxide or carbonate in a current of air, or by heating the oxide C0304 in a current of carbon dioxide.
For the quantitative determination of cobalt, it is either weighed as the oxide, C0304, obtained by ignition of the precipitated monoxide, or it is reduced in a current of hydrogen and weighed as metal.
Old Prince Bolkonski heard all the rumors current in the town from Mademoiselle Bourienne and had read the note to Princess Mary in which Natasha had broken off her engagement.
Pierre still went into society, drank as much and led the same idle and dissipated life, because besides the hours he spent at the Rostovs' there were other hours he had to spend somehow, and the habits and acquaintances he had made in Moscow formed a current that bore him along irresistibly.
The head of the family, Count Ilya Rostov, continually drove about the city collecting the current rumors from all sides and gave superficial and hasty orders at home about the preparations for their departure.
In metals the electrons can slip from one atom to the next, since a current can pass without chemical action.
To pass a steady current in the direction opposite to this electromotive force of polarization, the applied electromotive force E must exceed that of polarization E', and the excess E - E' is the effective electromotive force of the circuit, the current being, in accordance with Ohm's law, proportional to the applied electromotive force and represented by (E - E')/ R, where R is a constant called the resistance of the circuit.
The verification of Kohlrausch's theory of ionic velocity verifies also the view of electrolysis which regards the electric current as due to streams of ions moving in opposite directions through the liquid and carrying their opposite electric charges with them.
The surburban town is an odd mix of decay and gentrification in its current state.
The method of induction between insulated primary and secondary circuits laid out flat on the surface of the earth proves to be of limited application, and in his later experiments Preece returned to a method which unites both conduction and induction as the means of affecting one circuit by a current in another.
An interrupted current having a frequency of about 400 was used in the primary circuit, and a telephone was employed as a receiver in the secondary circuit.
Elec. Eng., 27, p. 938.) It may be explained as follows: - Suppose a battery on shore to have one pole earthed and the other connected to an insulated submarine cable, the distant end of which was also earthed; if now a galvanometer is inserted anywhere in the cable, a current will be found flowing through the cable and returning by various paths through the sea.
field created round one circuit to induce, when varied, a secondary current in another circuit, there have been certain attempts to utilize what may best be described as electrostatic induction.
In the primary circuit of the induction coil was an arrangement for rapidly intermitting the current and a key for short-circuiting this primary circuit.
This current may be taken to be of the order of two or three micro-amperes.
The idea was that variations of the primary current would create electromotive force in the secondary circuit which would act through the air condenser formed by the two plates.
On creating an electric spark or wave in the neighbourhood of the tube the resistance suddenly falls to a few ohms and the cell sends a current through it.
At the next instant it is the seat of an electric current and is surrounded by closed lines of magnetic force.
These spark balls are connected either to the secondary circuit of an induction coil I, or to that of an alternating current transformer having a secondary voltage of 20,000 to 100,000 volts.
In order to produce electric oscillations in the system, the first or alternating current transformer must charge the condenser connected to its secondary terminals, but must not produce a permanent electric arc between the balls.
The impedance of the primary or alternator circuit is so adjusted that when both the chokers are in circuit the current flowing is not sufficient to charge the condensers; but when one choker is short-circuited the impedance is reduced so that the condenser is charged, but the alternating arc is not formed.
As Dionysius of Halicarnassus (Judicium de Thucydide, c. 23) distinctly states that the work current in his time under the name of Cadmus was a forgery, it is most probable that the two first are identical with the Phoenician Cadmus, who, as the reputed inventor of letters, was subsequently transformed into the Milesian and the author of an historical work.
A known fraction of the current is then indicated and measured.
To explain these facts, Theodor Grotthus (1785-1822) in 1806 put forward an hypothesis which supposed that the opposite chemical constituents of an electrolyte interchanged partners all along the line between the electrodes when a current passed.
Interchanges must be supposed to go on whether a current passes or not, the function of the electric forces in electrolysis being merely to determine in what direction the parts of the molecules shall work their way through the liquid and to effect actual separation of these parts (or their secondary products) at the electrodes.
If the black ions move twice as fast as the white ones, the state of things after the passage of a current will be represented by the lower part of the figure.
Hittorf and many other observers have made experiments to determine the unequal dilution of a solution round the two electrodes when a current passes.
In some cases porous diaphragms have been employed; but such diaphragms introduce a new complication, for the liquid as a whole is pushed through them by the action of the current, the phenomenon being known as electric endosmose.
On the theory that the phenomena are wholly due to unequal ionic velocities this result would mean that the cation like the anion moved against the conventional direction of the current.
If some of the anions, instead of being simple iodine ions represented chemically by the symbol I, are complex structures formed by the union of iodine with unaltered cadmium iodide - structures represented by some such chemical formula as I(CdI 2), the concentration of the solution round the anode would be increased by the passage of an electric current, and the phenomena observed would be explained.
Clausius extended to electrolysis the chemical ideas which looked on the opposite parts of the molecule as always changing partners independently of any electric force, and regarded the function of the current as merely directive.
When two metallic conductors are placed in an electrolyte, a current will flow through a wire connecting them provided that a difference of any kind exists between the two conductors in the nature either of the metals or of the portions of the electrolyte which surround them.
A current can be obtained by the combination of two metals in the same electrolyte, of two metals in different electrolytes, of the same metal in different electrolytes, or of the same metal in solutions of the same electrolyte at different concentrations.
In accordance with the principles of energetics, any change which involves a decrease in the total available energy of the system will tend to occur, and thus the necessary and sufficient condition for the production of electromotive force is that the available energy of the system should decrease when the current flows.
In order that the current should be maintained, and the electromotive force of the cell remain constant during action, it is necessary to ensure that the changes in the cell, chemical or other, which produce the current, should neither destroy the difference between the electrodes, nor coat either electrode with a non-conducting layer through which the current cannot pass.
But the internal rearrangements which accompany the production of a current do not cause any change in the original nature of the electrodes, fresh zinc being exposed at the anode, and copper being deposited on copper at the cathode.
Thus as long as a moderate current flows, the only variation in the cell is the appearance of zinc sulphate in the liquid on the copper side of the porous wall.
But, on the other hand, if a few drops of acid be placed in the vessel with the platinum, bubbles of hydrogen appear, and a current flows, zinc dissolving at the anode, and hydrogen being liberated at the cathode.
When the applied electromotive force is diminished by an infinitesimal amount, the cell produces a current in the usual direction, and the ordinary chemical changes occur.
Now the effective change produced by the action of the current is the concentration of the more dilute solution by the dissolution of metal in it, and the dilution of the originally stronger solution by the separation of metal from it.
The concentration of the simple copper ions is then so much diminished that the copper plate becomes an anode with regard to zinc. Thus the cell - copper I potassium cyanide solution I potassium sulphate solution - zinc sulphate solution I zinc - gives a current which carries copper into solution and deposits zinc. In a similar way silver could be made to act as anode with respect to cadmium.
At first a considerable current is indicated by the galvanometer; the deflexion soon diminishes, however, and finally becomes very small.
If, instead of using a single Daniell's cell, we employ some source of electromotive force which can be varied as we please, and gradually raise its intensity, we shall find that, when it exceeds a certain value, about 1.7 volt, a permanent current of considerable strength flows through the solution, and, after the initial period, shows no signs of decrease.
This current is accompanied by chemical decomposition.
A current will flow for a while in the reverse direction; the system of plates and acidulated water through which a current has been passed, acts as an accumulator, and will itself yield a current in return.
Only when the applied electromotive force exceeds this reverse force of polarization, will a permanent steady current pass through the liquid, and visible chemical decomposition proceed.
The opposing force of polarization is about 1.7 volt, but, when the plates are disconnected and used as a source of current, the electromotive force they give is only about 1.07 volt.
But the ions of an electrolytic solution can move independently through the liquid, even when no current flows, as the consequences of Ohm's law indicate.
An electric current consists of a moving stream of electrons.
When a current passes from an electrolyte to a metal, the electron must be detached from the atom it was accompanying and chemical action be manifested at the electrode.
He gave amusing illustrations of the absurdity and poverty of the current pulpit oratory of his day, some of them being taken from the sermons of his own father.
The market price of commercial rubber is determined by the current price of " fine Para " from S.
ELECTROPLATING, the art of depositing metals by the electric current.
In the article Electrolysis it is shown how the passage of an electric current through a solution containing metallic ions involves the deposition of the metal on the cathode.
The vats for depositing may be of enamelled iron, slate, glazed earthenware, glass, lead-lined wood, &c. The current densities and potential differences frequently used for some of the commoner metals are given in the following table, taken from M ` Millan's Treatise on Electrometallurgy.
These require constant shifting because the objects are in contact at many points, and because the top ones shield those below from the depositing action of the current.
Care must be taken not to expose goods in the plating-bath to too high a current density, else they may be "burnt"; they must never be exposed one at a time to the full anode surface, with the current flowing in an empty bath, but either one piece at a time should be replaced, or some of the anodes should be transferred temporarily to the place of the cathodes, in order to distribute the current over a sufficient cathode-area.
The strength of the current may also be regulated by introducing lengths of German silver or iron wire, carbon rod, or other inferior conductors in the path of the current, and a series of such resistances should always be provided close to the tanks.
Ammeters to measure the volume, and voltmeters to determine the pressure of current supplied to the baths, should also be provided.
Very irregular surfaces may require the use of specially shaped anodes in order that the distance between the electrodes may be fairly uniform, otherwise the portion of the cathode lying nearest to the anode may receive an undue share of the current, and therefore a greater thickness of coat.
This solution, being an inferior conductor of electricity, requires a much higher electromotive force to drive the current through it, and is therefore more costly in use.
Sherard Cowper Coles patented a process in which, working with a high current density, a lead anode is used, and powdered zinc is kept suspended in the solution to maintain the proportion of zinc in the electrolyte, and so to guard against the gradual acidification of the bath.
Even pure gold, it may be noted, is darker or lighter in colour according as a stronger or a weaker current is used.
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.
Other alloys may be produced, such as bronze, or German silver, by selecting solutions (usually cyanides) from which the current is able to deposit the constituent metals simultaneously.
The leading products of the blast-furnace are argentiferous lead (base bullion), matte, slag and flue-dust (fine particles of charge and volatilized metal carried out of the furnace by the ascending gas current).
The Kassner process for the manufacture of oxygen depends upon the formation of calcium plumbate, Ca2Pb04, by heating a mixture of lime and litharge in a current of air, decomposing this substance into calcium carbonate and lead dioxide by heating in a current of carbon dioxide, and then decomposing these compounds with the evolution of carbon dioxide and oxygen by raising the temperature.
This office he held till the 12th of September 1863, when finding it impossible to resist the rising current of radicalism and revolution he resigned all his offices, and obtained at his own request unlimited leave of absence.
Literature - modern as well as ancient - occupied his attention; one of his works was a translation of four parts of Clarissa; and translations of some of the then current English paraphrases on biblical books manifested his sympathy with a school which, if not very learned, attracted him by its freer air.
A wire carrying an electric current is surrounded by a magnetic field, and if the wire is bent into the form of an elongated coil or spiral, a field having certain very useful qualities is generated in the interior.
A bar of soft iron introduced into the coil is at once magnetized, the magnetism, however, disappearing almost completely as soon as the current ceases to flow.
With suitable arrangements of iron and coil and a sufficiently strong current, the intensity of the temporary magnetization may be very high, and electromagnets capable of lifting weights of several tons are in daily use in engineering works.
If the bar inserted into the coil is of hardened steel instead of iron, the magnetism will be less intense, but a larger proportion of it will be retained after the current has been cut off.
In the internal field of a long coil of wire carrying an electric current, the lines of force are, except near the ends, parallel to the axis of the coil, and it is chiefly for this reason that the field due to a coil is particularly well adapted for inductively magnetizing iron and steel.
A magnetic field is generally due either to a conductor carrying an electric current or to the poles of a magnet.
The magnetic field due to a long straight wire in which a current of electricity is flowing is at every point at right angles to the plane passing through it and through the wire; its strength at any point distant r centimetres from the wire is H = 21/r, (2) i being the current in C.G.S.
3 The lines of force are evidently circles concentric with the wire and at right angles to it; their direction is related to that of the current in the same manner as the rotation of a corkscrew is related to its thrust.
We have seen that the efficiency of an electromagnetic engine is greatest when the current is indefinitely small, and then the rate at which it works is also indefinitely small.
When the zinc and copper plates are connected through a wire, a current flows, the conventionally positive electricity passing from copper to zinc in the wire and from zinc to copper in the cell.
If the external electromotive force exceed that of the cell by ever so little, a current flows in the opposite direction, and all the former chemical changes are reversed, copper dissolving from the copper plate, while zinc is deposited on the zinc plate.
Again, a steel wire through which an electric current has been passed will be magnetized, but so long as it is free from stress it will give no evidence of magnetization; if, however, the wire is twisted, poles will be developed at the two ends, for reasons which will be explained later.
Ask for the current chef's special, where you may get to sample delicacies such as kung pao baby lobster and sea bass fillets.
The restaurant hours change seasonally, so call for the most current hours of operation.
Magnetic fields arise from the flow of current.
Date listings proved none of the entries were current.
I didn't want to get too far away from what's cool and current.
This will be composed of a conduction and a convection current, the latter due to rising or falling air currents carrying ions.
This gives a convection current of 2.7 X108 electrostatic units, or about 1/27 of the conduction current.
Gerdien's estimate of the convection current is for fine weather conditions.
The four-book numbering is now the current one and is adopted in this article though there is little doubt that there were originally four books besides the Cynthia.
At Bagdad it has an average breadth of about 200 yards and a current in flood time of about 44 m.
They have so much in common that they must have drawn from the same current bodies of thought, or there must have been borrowing in one direction or the other.
The struggle between ethical religion and the current worship became acute toward the end of the 7th century.
Unless suitable fresh air inlets are provided, this form of stove will cause the room to be draughty, the strong current of warm air up the flue drawing cold air in through the crevices in the doors and windows.
Here we see the germs of Mendelssohn's Pragmatism, to use the now current term.
Some of the conservatives among the Jews opposed these innovations, but the current of progress was too strong for them.
In Lombardy it has a breadth of 200 yds., and a depth of 10 to 16 ft., but the strength of the current renders its navigation very difficult, and lessens its value as a means of transit between Germany and Italy.
When the crash came and the national treasury was found to be without resources to meet current expenses, further issues of $110,000,000 in currency were made.
Deposit and current accounts of Caisse des dpts, &c., including savings banks 15,328,840
Baumgarten of Halle (1706-1757) in disengaging the current dogmatic theology from its many scholastic and mystical excrescences, and thus paved a way for a revolution in theology.
It is decomposed by water, and with a solution of yellow phosphorus in carbon bisulphide it gives a red powder of composition PBI 2, which sublimes in vacuo at 210° C. to red crystals, and when heated in a current of hydrogen loses its iodine and leaves a residue of boron phosphide PB.
Nay, in the Roman church a practice of fasting on Saturday as well as on Friday was current before the time of Tertullian.
of England, on which a large southern land is shown, and the tradition of a Terra Australis appears to have been current for a long period before it enters into authentic history.
3, which identifies the blood with the soul of the animal and therefore prohibits its use fairly represents the current conception both among primitive peoples as well as among those who had advanced along the road of culture and civilization.
On reaching the South American coast, the southern equatorial current splits into two parts at Cape St Roque: one branch, the Brazil current, is deflected southwards and follows Currents.
the coast as a true stream current at least as far as the river Plate.
It may now be taken as generally admitted that the current referred to breaks into three main branches.
These branches are separated from one another at the surface by currents moving southwards: one passes east of Iceland; the second, the Greenland current, skirts the east coast of Greenland; and the third, the Labrador current already mentioned, follows the western side of Davis Strait.
On the polar side of the high-pressure area a west wind drift is under the control of the " roaring forties," and on reaching South Africa part of this is deflected and sent northwards along the west coast as the cold Benguella current which rejoins the equatorial.
The coast is low and sandy and is formed by the detritus deposited by the sea current called Calema.
If the current drive an electromagnetic engine, the reaction of the engine will produce an electromotive force opposing the current.
Suppose the current to be thus reduced to C'.
von Jacobi showed that for a given electromotive force in the battery the horse-power is greatest when the current is reduced to one-half of what it would be if the engine were at rest.
When they are worked from a power station the great advantage is gained that the same plant which drives them can be used for many other purposes, such as working machine tools and supplying current for lighting.
In electric cranes a useful method is to arrange the connexions so that the lifting motor acts as a dynamo, and, driven by the energy of the falling load, generates a current which is converted into heat by being passed through resistances.
In the second, or " braking off " method, the brake is automatically applied by a spring or weight, and is released either mechanically or, in the case of electric cranes, by the pull of a solenoid or magnet which is energized by the current passing through the motor.
When the motor starts the brake is released; when it stops, or the current ceases, the brake goes on.
The motor in most common use for electric cranes is the series wound, continuous current motor, which has many advantages.
Davy on the decomposition of the solutions of salts by the voltaic current were turned to account in the water voltameter telegraph of Sdmmering and the modification of it proposed by Schweigger, and in a similar method proposed by Coxe, in which a solution of salts was substituted for water.
C. Oersted, of the action of the galvanic current on a magnet.
4); a current is sent from a battery, E, through one coil of a galvanometer, g, through a high resistance, r, through one of the wires, r, and thence back from office B (at which the wires are looped), through wire 2, through another high resistance, r', through a second coil on the galvanometer, g, and thence to earth.
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.
If, however, there is leakage, the current received on the galvanometer will be less than the current sent out, and the result will be a deflection of the needle proportional to the amount of leakage.
The galvanometer being so adjusted that a current of definite strength through one of the coils gives a definite deflection of the needle, the amount of leakage expressed in terms of the insulation resistance of the wires is given by the formula.
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.
It is not possible to work double current from one set alone, as in this case, if one key of a group of instruments is up and another is down, the battery would be short-circuited and no current would flow to line.
in diameter, to a total resistance of zoo ohms. The actual current required to work the instrument is 3.3 milliamperes (equivalent approximately to the current given by 1 Daniell cell through 3300 ohms), but in practice a current of to milliamperes is allowed.
Recorders vary in details of construction, but all have the same object, namely, to record the intervals during which the current is applied to the line.
The earliest successful form was " Bright's bell " sounder, which consisted of two bells of distinct tone or pitch, one of which was sounded when the current was sent in one [[International Code O]] --- 4 - 5 p-- - 6 R - 7 '...'
40 ohms (or 900 ohms when worked from accumulators), and the instrument is worked with a current of 400 milliamperes (25 milli British Post Office.
- Closed Circuit, Singleis long and contains a large current System.
number of stations, the sending battery is sometimes divided among them in order to give greater uniformity of current along the line.
When only one battery is used the current at the distant end may be considerably affected by the leakage to earth along the line.
If long circuits were worked direct with ordinary instruments, high battery power would be required in order to send sufficient Single current to actuate the apparatus.
circuit-closing apparatus called a relay, which is practi cally an electromagnetic key which has its lever attached to the armature of the magnet and which can be worked by a very weak current.
When a current passes through R the armature A is attracted and the local circuit is closed through the armature at b.
The local 1_ E I battery B 1 then sends a current through the in FIG.
In this the tongue of the relay is kept over to the spacing side by means of a current flowing in one direction, but on the depression of the signalling key the current is reversed, moving the relay tongue over to the marking side.
the side on which no current passes through the local circuit.
The standard relay will work single current with a current of 3 milliamperes, though in practice about 10 would be used.
The relay tongue, being perfectly free to move, can be actuated by a comparatively weak current.
If the positive is called the signalling current, the line will be charged positively each time a signal is sent; but as soon as the signal is completed a negative charge is communicated FIG.
cut off, sets up an induced current of high tension, which causes a spark to jump across the contact points of the relay, and by oxidizing them makes it necessary for them to be frequently cleaned.
Suppose the key to be depressed, then a current flows through one winding of the differential relay to line and through the other winding and rheostat to earth.
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.
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.
In this case no current flows from the battery through the line or instruments, the whole action being inductive.
currents; the former is polarized and responds to reversals of current, while the latter is non-polarized and responds only to the increased current from K2 irrespective of the direction of that current.
Then, if a current is sent from the spring to the roller through the paper, a brown mark will be mace by the spring due to the liberation of iodine.
Thus for a dot, first a negative and then a positive current is sent to the line, the effect of the current continuing during the time required for the paper to travel the space between two holes.
Thus for a dash the interval between the positive and the negative current is equal to the time the paper takes to travel over twice the space between two successive holes.
For the dot the armature is deflected by the first current, the ink-wheel being brought into contact with the paper and after a short interval pulled back by the reverse current.
In the case of the dash the ink-wheel is brought into contact with the paper by the first current as before and is pulled back by the reverse current after three times the interval.
In Squier and Crehore's " Synchronograph " system " sine waves of current, instead of sharp " makes and breaks," or sharp reversals, are employed for transmitting signals, the waves being produced by an alternating-current dynamo, and regulated by means of a perforated paper ribbon, as in the Wheatstone automatic system.
The current thus sent to the line may be made either to act directly on the printing instrument or to close a local circuit by means of a relay.
The current then passes through the coils of an electromagnet, which releases the printing mechanism.
In the receiver there is a strong electromagnet, excited by a local current, which has in its circuit two annular air gaps, across which the magnetic field is practically uniform and constant.
Owing to the variable illumination of the selenium thus produced, the resistance of the latter, and therefore the intensity of the current sent through the line to the receiving station by the battery, will be altered accordingly.
When there is no current the shutter covers the perforations and no light passes, but when a current traverses the wires they are depressed by electromagnetic action, carrying the shutter with them, and a quantity of light proportional to the current strength is admitted through the perforations.
The conductor of the cable is practically insulated, as the condensers in the bridge have a very high resistance; hence no appreciable current ever flows into or out of the line.
galvanometer coil so that the influence of the latter causes the mirror (through the action of the magnetic needle) to be turned through a small angle in one direction or the other according to the direction of the current through the coil.
In what is known as the " hybrid " form of recorder the permanent magnets are provided with windings of insulated copper wire; the object of these windings is to provide a means of " refreshing " the magnets by means of a strong current temporarily sent through the coils when required, as it has been found that, owing to magnetic leakage and other causes, the magnets tend to lose their power, especially in hot climates.
This magnet is excited by an alternating current, and the current induced in the second coil is after rectification sent through an ordinary siphon recorder.
As the direction and intensity of this induced current are a function of the position of the second coil in its field, and as this position is determined by its mechanical connexion with the recorder coil, it is evident that, by a suitable choice of the electrical elements of the second coil and its alternating field, the indications on the siphon recorder can be magnified to any reasonable extent.
a signal to take more, and at the end of the element less of the total arrival current from the cable than would traverse it if the shunt were non-inductive.
sending current enters an adjustable mid-point in the g coil and passes through the two halves of the winding to the ends connected to the cable and artificial line respectively.
To 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 advantage of using the magnetic bridge duplex method is that the maximum current is sent to line or cable, and the receiving system benefits accordingly.
Under these circumstances a small portion of the current from the battery is shunted through the galvanometer circuit, and can be used to make electric signals.
If the current is interrupted or alternating, and if a telephone receiver has its terminals connected to a separate metallic circuit joined by earth plates at two other places to the earth, not on the same equipotential surface of the first circuit, sounds will be heard in the telephone due to a current passing through it.
He proposed that one ship should be provided with the means of making an interrupted current in a circuit formed partly of an insulated metallic wire connected with the sea at both ends by plates, and partly of the unlimited ocean.
Canal system of flow lines of current through the sea, and these might be detected by any other ships furnished with two plates dipping into the sea at stem and stern, and connected by a wire having a telephone in its circuit, provided that the two plates were not placed on the same equipotential surface of the original current flow lines.
By the use of a key in the battery circuit as well as an interrupter or current reverser, signals can be given by breaking up the continuous hum in the telephone into long and short periods.
adjust the frequency so that it has the value of the normal time period of the circuit formed of the condenser and transformer secondary circuit, and thus it is possible to obtain condenser oscillatory discharges free from any admixture with alternating current arc. In this manner the condenser discharge can be started or stopped at pleasure, and long and short discharges made in accordance with the signals of the Morse FIG.
These wave-detecting devices may be divided into two classes: (i) potential operated detectors, and (ii) current operated detectors.
Fessenden employed a simple fine loop of Wollaston platinum wire in series with a telephone and shunted voltaic cell, so that when electric oscillations passed through the fine wire its resistance was increased and the current through the telephone suddenly diminished (R.
If then oscillations are sent through the other pair heat is produced at the junction and the galvanometer indicates a thermoelectric current (Wied.
traversed by a current and deflected in the field.
The thermal G G detectors are especially useful for the purpose of quantitative measurements, because they indicate the true effective or square root of mean square value of the current or train of oscillations passing through the hot wire.
Fleming discovered that if the filament is made incandescent by the current from an insulated battery there is a unilateral conductivity of the rarefied gas between the hot filament and the metal plate, such that if the negative terminal of the filament is connected outside the lamp through a coil in which electric oscillations are created with the platinum plate, only one half of the oscillations are permitted to pass, viz., those which carry negative electricity from the hot filament to the cooled plate through the vacuous space.
A battery with a sufficient number of cells is connected to these two electrodes so as to pass a current through the mercury vapour, negative electricity proceeding from the mercury cathode to the iron anode.
He showed that in a simple Marconi antenna the variations of potential are a maximum at the insulated top and a minimum at the base, whilst the current amplitudes are a maximum at the top earthed end and zero at the top end.
The station was opened shortly afterwards for public service, the rates being greatly below that then current for the cable service.
771818) to employ a receiving antenna consisting of vertical wires held in a frame which could be swivelled round into various positions and used to locate the position of the sending station by ascertaining the position in which the frame must be placed to create in it the maximum oscillatory current.
Also he showed that if such an antenna had its horizontal part swivelled round into various directions the current created in a distant receiver antenna varied with the azimuth, and when plotted out in the form of a polar curve gave a curve of a peculiar figure-of-8 shape.
Duddell discovered in 1900 that if a continuous current carbon arc had its carbon electrodes connected by a condenser in series with an inductance, then under certain conditions oscillations were excited in this condenser circuit which appeared to be continuous.
Increase in the voltage acting upon a solid conductor increases the current through it, but in the case of the electric arc an increase in current is accompanied by a fall in the difference of potential of the carbons, within certain limits, and the arc has therefore been said to possess a negative resistance.'
Duddell, " On Rapid Variations in the Current through the Direct Current Arc," Journ.
The capacity of the condenser is then altered until the maximum current, as indicated by a hot wire ammeter, is produced in the circuit.
It does not melt at a white heat, and is easily reduced to the metal by heating in a current of hydrogen or with carbon.
5 The writer recommended the use of a flexible plate at the source of sound, which would vibrate in response to the varying pressure of the bons' air, and thus open and close an electric circuit, and of a similar plate at the receiving station, which would be acted on electromagnetically and thus give out as many pulsations as there are breaks in the current.
His fundamental idea - the interruption of the current - was a fatal mistake, which was not at the time properly understood.
His aim was the production, by means of the undulations of pressure on a membrane caused by sound, of an electric current the strength of which should at every instant vary directly as the pressure varied).
The instrument was joined in circuit with a battery and another similar instrument placed at a distance; and a continuous current was made to flow through the circuit, keeping the electromagnets energized.
The receiver was based on the change of friction produced by the passage of an electric current through the point of contact of certain substances in relative motion.
The current from the line was made to pass through the spring and paper to the cylinder.
In these experiments the electric current passed through the fingers of the operator's hand, which thus took the place of the spring in Edison's apparatus.
When the current passed, the friction was felt to increase, and the effect of sending a rapidly undulating current through the arrangement was to produce a sound.
Acting upon this discovery, he constructed an instrument which he called a " microphone," 6 and which consisted essentially of two hard carbon electrodes placed in contact, with a current passing through the point of contact and a telephone included in the same circuit.
When the sounding board was spoken to or subjected to sound-waves, the mechanical resistance of the loose electrode, due to its weight, or the spring, or both, served to vary the pressure at the contact, and this gave to the current a form corresponding to the sound-waves, and it was therefore capable of being used as a speaking-telephone transmitter.'
The current from the battery used passed from the diaphragm through the granulated carbon to the metallic back of the box.
The current from the battery passes from one of the carbon disks to the other through the particles of granulated carbon which fill the space between them.
50) embodies the idea of supplying current to the transmitters over the line wires in parallel instead of round the loop circuit, as in the other systems referred to.
A current then flows and in passing round the circuit operates the line relay, with the result that the calling-lamp is lighted.
The subscriber's meter is joined in multiple with the cut-off relay, and whenever a peg is connected to the circuit a current flows through the meter.
This current is small, however, and the meter is not operated until a much larger current is passed through it.
When the relay is operated it connects a bell between one of the wires of the circuit and earth, while the bell itself is arranged to respond to current pulsations in one direction only.
This system of course requires that the exchange equipment shall include machines _ capable of delivering a positive pulsating current and a negative pulsating current, besides the usual alternations required for the ringing of ordinary subscribers.
As no practical process of telephone relaying has been devised, it is extremely important that the character of the line should be such as to favour the preservation of the strength and form of the telephone current.
The banks may buy up mortgages and advance money on current account on the security of land or buildings.
The islands are briefly noticed by Marco Polo, who probably saw without visiting them, under the name Angamanain, seemingly an Arabic dual, "The two Angamans," with the exaggerated but not unnatural picture of the natives, long current, as dog-faced Anthropophagi.
The reduction of the tentacles in all these forms may be correlated with their mode of life, and especially with living in a constant current of water, which brings foodparticles always from one direction and renders a complete whorl or circle of tentacles unnecessary.
When Gotama the Buddha, himself a Kosalan by birth, determined on the use, for the propagation of his religious reforms, of the living tongue of the people, he and his followers naturally made full use of the advantages already gained by the form of speech current through the wide extent of his own country.
Molybdenum dioxide, Mo02, is formed by heating sodium trimolybdate, Na2M03010, to redness in a current of hydrogen (L.
Molybdenum trichloride, MoC1 31 is obtained when the pentachloride is heated to a temperature of about 250° C. in a current of hydrogen.
It is readily oxidized by nitric acid, and when strongly heated_ in a current of hydrogen is reduced to the metallic condition.
The performances of Los Comuneros were attended by members of the different parties; the utterances of the different characters were taken to represent the author's personal opinions, and every speech which could be brought into connexion with current politics was applauded by one half of the house and derided by the other half.
So far as can be judged, Ayala had no strong political views, and drifted with the current of the moment.
It is from such a living and assimilating cell, performing as it does all the vital functions of a green plant, that, according to current theory, all the different cell-forms of a higher plant have been differentiated in the course of descent.
These forces however fail to furnish a complete explanation of the ascent of the current, and others have been thought to supplement them, which have more or less weight.
This wood is in great part already dead substance, but the mycelium gradually invades the vessels occupied with the transmission of water up the trunk, cuts off the current, and so kills the tree; in other cases such Fungi attack the roots, and so induce rot and starvation of oxygen, resulting in fouling.
The enhanced metabolism creates a current of draught on the supplies of available food-stuffs around.
Investigations of every kind which have been based on original sources of knowledge may be styled "research," and it may be said that without "research" no authoritative works have been written, no scientific discoveries or inventions made, no theories of any value propounded; but the word also has a somewhat restricted meaning attached to it in current usage.
By the action of dilute nitric acid; orthoand para-nitrophenols are obtained, the ortho-compound being separated from the para-compound by distillation in a current of steam.
Owing to the fact that the material collected by Mordecai was left to his pupils to arrange, the work was current in two recensions, an Eastern (in Austria) and a Western (in Germany, France, &c.).
in depth, with a breadth of 250 yds., and a current of 4 m.
Through this part of its course the current of the river, except where restricted by floating bridges - at Feluja, Mussaib, Hillah, Diwanieh and Samawa - does not normally exceed a mile an hour, and both on the main stream and on its canals the jerd or oxbucket takes the place of the naoura or water-wheel for purposes of irrigation.
The Hegelian identity of being and thought is also abandoned and the truth of realism acknowledged, an attempt being made to exhibit idealism and realism as respectively incomplete but mutually complementary systems. Ulrici's later works, while expressing the same views, are 1 :trgely occupied in proving the existence of God and the soul from the basis of scientific conceptions, and in opposition to the materialistic current of thought then popular in Germany.
In the deltas of shoal rivers, with a strong tide or current and no land visible, a 5 lb lead is substituted for the log-ship; the lead rests on the bottom, and the speed is obtained in a manner similar to that previously described.
It may be obtained from argyrodite by heating the mineral in a current of hydrogen; or by heating the dioxide to redness with carbon.
By heating the disulphide in a current of hydrogen, germanious sulphide, GeS, is formed.
Sulphuretted hydrogen, H 2 S, a compound first examined by C. Scheele, may be obtained by heating sulphur in a current of hydrogen, combination taking place between 200° C. and 358° C., and being complete at the latter temperature, dissociation taking place above this temperature (M.
This deprives parliament of control over the administrative departments, all the ministries being thus " armour-plated " - to use the cant phrase current in Russia - except that of ways and communications (railways).
That opportunity came when Basil died in 1533, leaving as successor a child only three years old, and the chances seemed all on the side of the nobles; but the result belied the current expectations, for the child came to be known in history as Ivan the Terrible, and died half a century later in the full enjoyment of unlimited autocratic power.
Dewsnup (ed.), Railway Organization and Working (Chicago, 1906); Interstate Commerce Commission; Rate Regulation Hearings before the U.S. Senate Committee (Washington, 5 vols., 1905); and on current matters, The Official Railway Guide (monthly, New York, the Railroad Age Gazette (weekly, New York) and the Commercial and Financial Chronicle (weekly, New York).
In the United States a committee of the American Society of Civil Engineers, appointed to consider the question of rail manufacture in consequence of an increase in the number of rail-failures, issued an interim report in 1907 in which it suggested a range of carbon from 0-55 to 0-65% for the heaviest sections of Bessemer steel flange rails, with a phosphorus maximum of 0.085%; while the specifications of the American Society for Testing Materials, current at the same period, put the carbon limits at o 45 to 0-55%, and the phosphorus limit at o io.
A current development is the application of superheaters to locomotives, and the results obtained with them are exceedingly promising.
The current required for it is generated by dynamos driven from the axles of the coaches.
It is necessary that the voltage of the current shall be constant whatever be the increase of the speed of the train, and therefore of the dynamo.
The maintenance of the requisite plant and the high wages current render such repairs somewhat costly.
Apocalyptic, as Baldensperger has shown, formed a counterpoise to the normal current of conformity to law.
From the sense of having full vigour, living or lively qualities or movements, the word, got its chief current meaning of possessing rapidity or speed of movement, mental or physical.
An almost identical story was current in the neighbourhood of Tilphossa, a Boeotian spring.
Then in 1763 was delivered his speech in "The Parson's Cause" - a suit brought by a clergyman, Rev. James Maury, in the Hanover County Court, to secure restitution for money considered by him to be due on account of his salary (16,000 pounds of tobacco by law) having been paid in money calculated at a rate less than the current market price of tobacco.
The step to magnetic phenomena was comparatively simple; but it was otherwise as regards electromagnetic phenomena, where current electricity is essentially involved.
An old popular belief current in different countries, and derived from common observation, connected mosquitoes with malaria, and from time to time this theory found support in more scientific quarters on general grounds, but it lacked demonstration and attracted little attention.
Theological writers were not in the least prepared to question the worth of the marvellous descriptions of creatures that were current in the schools on the faith of authorities vaguely known as "the history of animals," "the naturalists," and "the naturalist" in the singular number (Ouo-coMyos).
Before leaving the subject of classification it may be noted in passing that in 1906 Professor Lameere, of Brussels, proposed a :scheme for the classification of Diptera which as regards both the limits of the families and their grouping into higher categories, differs considerably from that in current use.
Personally he was not enthusiastic over the African enterprise, as it introduced new and, to him, unaccustomed and unwelcome values into Italian political life; but he realized that public opinion demanded it and he did not care to run counter to the current.
But as tribal names they invited explanation, and of the many characteristic traditions which were doubtless current a number have been preserved, though not in any very early dress.
- Biblical history previous to the separation of Judah and Israel holds a prominent place in current ideas, since over two-fifths of the entire Old Testament deals with these early ages.
If the impression left upon current thought can be estimated from certain of the utterances of the court-prophet Isaiah and the Judaean countryman Micah, the light which these throw upon internal conditions must also be used to gauge the real extent of the religious changes ascribed to Hezekiah.
Popular stories with many features of popular religion were current.
Henderson's own works are chiefly contributions to current controversies, speeches and sermons.
He found there, as he subsequently explained, the most confused ideas current as to the aims of the Allies in the war, and deliberate perversions circulated by enemy agents.
Congress granted another township (thirty-six sections) for the university in 1892, and its income is supplemented by legislative appropriations for current expenses and special needs.
The site doesn't look very good with the current layout.
It proves that much of the terminology of German mysticism was current before Eckhart's time.
The native rulers of Roshan and Shignan claim descent from Alexander the Great, of whom legends are still current in the country about the upper Oxus.
The only element of uncertainty was caused by the retardation of the current, which between Potsdam and Teheran (3000 m.) took 0 8.20 to travel; but it is probable that the final value can be accepted as correct to within os 05.
The current of air flowing in from over the sea is gradually diverted towards the area of least pressure, and at the same time is dissipated and loses much of its original force.
Such a reduction of temperature is brought about along the greater part of the coasts of India and of the BurmoSiamese peninsula by the interruption of the wind current by continuous ranges of mountains, which force the mass of air to rise over them, whereby the air being rarefied, its specific capacity for heat is increased and its temperature falls, with a corresponding condensation of the vapour originally held in suspension.
The cessation of the rains on the southern border of Baluchistan, west of Karachi, obviously arises from the projection of the south-east coast of Arabia, which limits the breadth of the south-west monsoon air current and the length of the coast-line directly exposed to it.
This police report at least serves to show the kind of rumour then current.
This could not but have an influence on the current ideas concerning David.
The last designation, which became the current one, was un doubtedly unfortunate, and has conveyed to many a false impression of Scottish philosophy.
But the exact meaning which he attaches to such expressions is not quite clear; and they occur, moreover, only incidentally and with the air of current phrases mechanically repeated.
C. Oersted's discovery that a magnetic needle is acted on by a voltaic current.
The simplest modes of preparing pure glycerin are based on the saponification of fats, either by alkalis or by superheated steam, and on the circumstance that, although glycerin cannot be distilled by itself under the ordinary pressure without decomposition, it can be readily volatilized in a current of superheated steam.
current popular corruption of shimo'n = Ishmael.
8) was probably the current one in later Roman times.
A contemporary of Aquinas, he opposed several of the dominant theories of the time, and united with the current Aristotelian doctrines a strong infusion of Platonism.
On this subject Henry is far from clear; but he defends Plato against the current Aristotelian criticism, and endeavours to show that the two views are in harmony.
In the feeding experiments which have been carried on at Rothamsted it has been shown that the amount consumed both for a given live weight of animal within a given time, and for the production of a given amount of increase, is, as current food-stuffs go, measurable more by the amounts they contain of digestible and available non-nitrogenous constituents than by the amounts of the digestible and available nitrogenous constituents they supply.
Hence, as current fattening food-stuffs go - assuming, of course, that they are not abnormally low in the nitrogenous constituents - they are, as foods, more valuable in proportion to their richness in digestible and available nonnitrogenous than to that of their nitrogenous constituents.
While mainly occupied in those years with philosophical studies, Mill did not remit his interest in current politics.
It was characteristic of the closeness with which he watched current events, and of his zeal in the cause of "lucidity," that when the Reader, an organ of science and unpartisan opinion, fell into difficulties in 1865 Mill joined with some distinguished men of science and letters in an effort to keep it afloat.
By this expression we do not mean an ideal mode of living, but the habits and requirements of life generally current in a community or grade of society at a given period.
The minute structure of the epithelium which clothes it, as well as the origin of the nerve which is distributed to the parabranchia, proves it to be the same organ which is found universally in molluscs at the base of each gill-plume, and tests the indrawn current of water by the sense of ?,g smell.
This distinction was already current in the catechetical school of Alexandria, but Origen gave it its boldest expression, and justified it on the ground of the incapacity of the Christian masses to grasp the deeper sense of Scripture, or unravel the difficulties of exegesis.
A strong current sets round the head of the Adriatic from east to west.
This current catches the silt brought down by the rivers and projects it in long banks, or lidi, parallel with the shore.
But with the decline of Venice the trade of the port fell off; the mouth of the Lido entrance became gradually silted up owing to the joint action of the tide and the current, and for many years complete stagnation characterized the port.
part of the state have a rapid current.
Roger completed his studies at Oxford, though not, as current traditions assert, at Merton or at Brasenose, neither of which had then been founded.
Revenues were not realized adequate to its lavish undertakings, and loans were used to meet current expenses.
The debt per capita is as high as the cost of current administration relatively to other cities.
The Arabian tribes began to take possession of the partly cultivated lands east of Canaan, became masters of the Eastern trade, gradually acquired settled habits, and learned to speak and write in Aramaic, the language which was most widely current throughout the region west of the Euphrates in the time of the Persian Empire (6th-4th century B.C.).
There is no actual proof that this spider is more poisonous than others, but it is a significant fact that its species, inhabiting countries as widely separated as Chile, Madagascar, Australia, New Zealand and South Europe are held in great fear by the indigenous population, and many stories are current of serious or fatal results following their bites.
In the absence of express agreement or custom or statutory provision (such as is made by the Agricultural Holdings Act 1883), a tenancy from year to year is determinable on half a year's notice expiring at the end of some current year of the tenancy.
The stronger current of modern authority is in favour of the landlords and not in favour of restricting the meaning of covenants of this class.
If at least half of the harvest in any year is destroyed by accident, the lessee (a) in the case of a lease for several years, obtains, at the end of his lease, a refund of rent, by way of indemnity, unless he has been indemnified by preceding harvests; (b) in the case of a lease for a year only, may secure a proportional abatement of the current rent.
The term, however, is somewhat elastic in its current use, and students of centipedes and spiders are often reckoned among the entomologists.
There were no printed circulars, except the monthly prices current of all kinds of produce, but brokers used to send particulars of business done to their customers in letters.
Thus in January the futures quoted will be January (technically termed " current," " present month " or near month," " futures "), January-February, " February-March, March-April, April-May, May-June, June-July, July-August, and perhaps two or three more.
Each group, it will be observed, except " current futures," culminates in two defined months.
Then, according as the spinner wants immediate delivery or delivery in some future month, he pays the price of current " futures," or of " futures " of the month in which he requires delivery, plus or minus the " points on or off " previously fixed.
" Current futures " would be affected more than "spot" by this impression as to the relation of " spot" to a conceived normal price for the year, and they might therefore be expected to drop more than "spot" when this impression was at all widely entertained.
But the fall of "current futures" would be checked by the demands that must be satisfied in the near future.
For current information the following may be added: Nield's, Ellison's and Tattersall's circulars; Cotton (the publication of the Manchester Cotton Association); and daily reports and articles in the local press.
[During the middle ages his work was current in a French translation, known as the Chronique d'outremer, or the Livre or Roman d'Eracles (so called from the reference at the beginning to the emperor Heraclius).
For current information see the annual report on Basutoland (Colonial Office, London).
A continuous electric current of one ampere is defined to be one which deposits electrolytically 0.001118 of a gramme of silver per second from a neutral solution of silver nitrate.'
An alternating current of one ampere is defined to be one which produces the same heat in a second in a wire as the unit continuous current defined as above to be one ampere.
In their simplest form they consist of a wire through which passes the current to be measured, some arrangement being provided for measuring the small expansion produced by the heat generated in the wire.
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.
There is therefore a certain ratio in which any current passing through the ammeter is divided between the shunt and the working wire.
Then no changes of external temperature can affect the sag of the wire, and the only thing which can alter its length relatively to the supporting bar is the passage of a current through it.
Hot-wire ammeters are open to the following objections: The scale divisions for equal increments of current are not equal in length, being generally much closer together in the lower parts of the scale.
The reason is that the heat produced in a given time in a wire is proportional to the square of the strength of the current passing through it, and hence the rate at which the heat is produced in the wire, and therefore its temperature, increases much faster than the current itself increases.
From this it follows that hot-wire ammeters are generally not capable of giving visible indications below a certain minimum current for each instrument.
The instrument therefore does not begin to read from zero current, but from some higher limit which, generally speaking, is about one-tenth of the maximum, so that an ammeter reading up to io amperes will not give much visible indication below i ampere.
In the construction of such an instrument it is essential that the wire should be subjected to a process of preparation or " ageing," which consists in passing through it a fairly strong current, at least the maximum that it will ever have to carry, and starting and stopping this current frequently.
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.
If a small alternating current is passed through one wire, it sags down, the mirror is tilted, and the spot of light on the screen is displaced.
The instrument can be calibrated by a continuous current.
When a current is passed through the wire, continuous or alternating, it creates heat, which expands the air in the bulb and forces the liquid up one side of the U-tube to a certain position in which the rate of loss of heat by the air is equal to the rate at which it is gaining heat.
- Another large class of ammeters depend for their action upon the fact that an electric current create; an electric field round its conductor, which varies in strength from point to point, but is otherwise proportional to the current.
When a current is passed through the coil the iron tends to move nearer to the coil of the wire where the field is stronger and so displaces the index needle over the scale.
When a current is passed through the wire forming the coil, the fragment of iron is drawn more into the aperture of the coil where the field is stronger and so displaces an index needle over a scale.
In the construction of this soft-iron instrument it is essential that the fragment of iron should be as small and as well annealed as possible and not touched with tools after annealing; also it should be preferably not too elongated in shape so that it may not acquire permanent magnetization but that its magnetic condition may follow the changes of the current in the coil.
If these conditions are not fulfilled sufficiently, the ammeter will not give the same indications for the same current if that current has been reached (a) by increasing from a smaller current, or (b) by decreasing from a larger current.
A much better form of electromagnetic ammeter can be constructed on a principle now extensively employed, which consists in pivoting in the strong field of a permanent magnet a small coil through which a part of the current to be measured is sent.
In this magnetic field is pivoted a small circular or rectangular coil carried in jewelled bearings, the current being passed into and out of the movable coil by fine flexible conductors.
The coil is so situated that, in its zero position when no current is passing through it, the plane of the coil is parallel to the direction of the lines of force of the field.
When a current is passed through the coil it rotates in the field and displaces the index over the scale against the control of a spiral spring like the hairspring of a watch.
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.
In this last case the shunt need not be contained in the instrument itself but may be at a considerable distance, wires being brought from the shunt which carries the main current to the movable coil ammeter itself, which performs the function simply of an indicator, 3.
The current can be passed into and out of the movable coil by permitting the ends of the coil to dip into two mercury cups.
If a current is passed through the fixed coil and movable coil in series with one another, the movable coil tends to displace itself so as to bring the axes of the coils, which are normally at right angles, more into the same direction.
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 be provided with a curve or table showing the current corresponding to each angular displacement of the torsion head.
electrodynamometer principle for use with large currents has been that of getting the current into and out of the movable conductor, and yet permitting that conductor to remain free to move under very small force.
The great novelty in the ampere balances of Lord Kelvin was a joint or electric coupling, which is at once exceedingly flexible and yet capable of being constructed to carry with safety any desired current.
A current entering by the trunnion -}- B flows round the two halves of the circuit, as shown by the arrows, and comes out at the trunnion - B.
5 the current is shown dividing round the two rings; but in all the balances, except those intended for the largest currents, the current really circulates first round one ring and then round the other.
6) are such that when a current is passed through the whole of the coils in series, forces of attraction and repulsion are brought into existence which tend to force one movable coil upwards and the other movable coil downwards.
When a current is passed through the instrument it causes one end of the movable system to tilt downwards, and the other end upwards; the sliding weight is then moved along the tray by means of a silk cord until equilibrium is again established.
The value of the current in amperes is then .?.
Since the current passing through the balance when equilibrium is obtained with a given weight is proportional to the square root of the couple due to this weight, it follows that the current strength when equilibrium is obtained is proportional to the product of the square root of the weight used and the square root of the displacement distance of this weight from its zero position.
Each instrument is accompanied by a pair of weights and by a square root table, so that the product of the square root of the number corresponding to the position of the sliding weight and the ascertained constant for each weight, gives at once the value of the current in amperes.
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.
Kelvin ampere balances are made in two types - (i) a variable weight type suitable for obtaining the ampere value of any current within their range; and (2) a fixed weight type intended to indicate when a current which can be varied at pleasure has a certain fixed value.
A fixed weight is placed on one coil and the current is varied gradually until the balance is just in equilibrium.
In these circumstances the current is known to have a fixed value in amperes determined by the weight attached to the instrument.
A steady continuous current is then passed through the ammeter and low resistance, placed in series with one another and adjusted so as to give any required scale reading on the ammeter.
The potential difference of the ends of the low resistance is at the same time measured on the potentiometer, and the quotient of this potential difference by the known value of the low resistance gives the true value of the current passing through the ammeter.
All this, however, must necessarily be of the nature of the purest speculation, and the only facts which we are able to deduce in the present state of our knowledge of the subject may be summed up as follows: (a) That the Malays ethnologically belong to a race which is allied to the Polynesians; (b) that the theory formerly current to the effect that the Sakai and other similar races of the peninsula and archipelago belonged to the Malayan stock cannot be maintained, since recent investigations tend to identify them with the Mon-Annam or Mon-Khmer family of races; (c) that the Malays are, comparatively speaking, newcomers in the lands which they now inhabit; (d) that it is almost certain that their emigration took place from the south; (e) and that, at some remote period of their history, they came into close contact with the Polynesian race, probably before its dispersion over the extensive area which it now occupies.
After 1879 a theory became current in Germany (first stated in P. E.
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.
The idea of transmutation, in the country of its origin, had a philosophical basis, and was linked up with the Greek theories of matter there current; thus, by supplying a central philosophical principle, it to some extent unified and focussed chemical effort, which previously, so far as it existed at all, had been expended on acquiring empirical acquaintance with a mass of disconnected technical processes.
Frazer maintains the hitherto current theory that the earlier temple of Athena and Erechtheus was on the site of the Erechtheum; that the Erechtheum inherited the name apXa ios veclis from its predecessor, and that the " opisthodomos " in which the treasures were kept was the west chamber of the Parthenon; Furtwangler and Milchh6fer hold the strange view that the " opisthodomos " was a separate building at the east end of the Acropolis, while Penrose thinks the building discovered by Dorpfeld was possibly the Cecropeum.
The residue is then fused with caustic potash and nitre, dissolved in water, saturated with chlorine and distilled on the water-bath in a current of chlorine.
Ruthenium in bulk resembles platinum in its general appearance, and has been obtained crystalline by heating an alloy of ruthenium and tin in a current of hydrochloric acid gas.
The dioxide, Ru02, is formed by heating sulphate, or by heating the metal in a current of oxygen.
The rivers and neighbouring seas seem to be well stocked with fish, and especial mention must be made of the turtles, flying-fish, and brilliant I coral-fish which swarm in the waters warmed by the Kurosiwo current, the gulf-stream of the Pacific. Shell-fish form an important article of diet to both the Chinese and the aborigines along the coast - a species of Cyrena, a species of Tapes, Cytheraea petechiana and Modiola teres being most abundant.
Reinforcements were also brought up from San Juan and preparations made to resist an attack by the Americans, despite the current rumours of approaching peace.
These faults are of less importance during the period when Greek and Roman writers notice the affairs of Britain; but they become more serious when, as is the case from nearly the beginning of the 5th century to the date of his death, Gildas's brief narrative is our only authority for most of what passes current as the history of our island during those years.
For example, the physicist determines the density, elasticity, hardness, electrical and thermal conductivity, thermal expansion, &c.; the chemist, on the other hand, investigates changes in composition, such as may be effected by an electric current, by heat, or when two or more substances are mixed.
Berzelius's investigation of the action of the electric current on salts clearly demonstrated the invaluable assistance that electrolysis could render to the isolator of elements; and the adoption of this method by Sir Humphry Davy for the analysis of the hydrates of the metals of the alkalis and alkaline earths, and the results which he thus achieved, established its potency.
In quantitative analysis the methods can be subdivided into: (a) gravimetric, in which the constituent is precipitated either as a definite insoluble compound by the addition of certain reagents, or electrolytically, by the passage of an electric current; (b) volumetric, in which the volume of a reagent of a known strength which produces a certain definite reaction is measured; (c) colorimetric, in which the solution has a particular tint, which can be compared with solutions of known strengths.
The quantitative precipitation of metals by the electric current, although known to Michael Faraday, was not applied to analytical chemistry until O.
The ever-increasing importance of the electric current in metallurgy and chemical manufactures is making this method of great importance, and in some cases it has partially, if not wholly, superseded the older methods.
(7) Electrolytic. - This method consists in decomposing a solution of a salt of the metal by the electric current and weighing the metal deposited at the cathode.
The electrolysis is generally conducted with platinum electrodes, of which the cathode takes the form of a piece of foil bent into a cylindrical form, the necessary current being generated by one or more Daniell cells.
If all the connexions are sound, the copper oxide is gradually heated from the end a, the gas-jets under the spiral d are lighted, and a slow current of oxygen is passed through the tube.
The oxidation, which is effected by chromic acid and sulphuric acid, is conducted in a flask provided with a funnel and escape tube, and the carbon dioxide formed is swept by a current of dry air, previously freed from carbon dioxide, through a drying tube to a set of potash bulbs and a tube containing soda-lime; if halogens are present, a small wash bottle containing potassium iodide, and a U tube containing glass wool moistened with silver nitrate on one side and strong sulphuric acid on the other, must be inserted between the flask and the drying tube.
The platinum is maintained at a bright red heat, either by a gas flame or by an electric furnace, and the vapour is passed over it by leading in a current of oxygen.