Double Sentence Examples
He reached a set of double doors.
Glancing in the mirror, he did a double take when he saw her.
Carmen glanced at Alex and did a double take.
First she opened the double doors in the kitchen and found the spacious dining room.
She turned where he indicated, noticing the double French doors for the first time.Advertisement
It's raining enough to make Noah do a double shift.
Perhaps we should charge her for a double room when Belfair shows up.
Run to the end of this hall, then go out the double doors to the left.
What's the heat if I double rent once in awhile?
This man, bent double, rushed past the tradesman and the officer.Advertisement
The small book it hefted made its stooped posture almost double over.
Hopefully he had no idea how her heart beat double time occasionally at the strangest things.
He pointed as he walked, indicating the dining room, the library, the reception room, and others, each sounding stuffier than the last and all marked by polished oak double doors.
They accurately described the construction of DNA as a double helix and showed how its structure made replication both possible and reliable.
The debts amounted to double the value of the property.Advertisement
Brady walked the area between the double walls, looking for anything or anyone in a large enough piece to provide clues as to what was going on.
The cost of their imported food doubles, and I guarantee you the foreign-owned factory won't double wages as a result.
Tears made the rainbow double.
The capsule has a double wall,.
Be sure to try the restaurant's signature dessert, double chocolate bread pudding, on a night when you won't need your energy for hiking the next day.Advertisement
Whatever he's paying you, I'll double.
It was a double sheet from the Parkside Sentinel.
Most of her bedding was worn and made for a double bed.
Her mate and father were near the same age, over double her eighteen years.
Relieved, horrified, she focused on subduing the demon, whose angry pacing in her chest made her want to double over in pain.Advertisement
They rode double on Ed from the house to the stable.
Even if the agent made no profit he was bound to return double what he had received, if he made poor profit he had to make up the deficiency; but he was not responsible for loss by robbery or extortion on his travels.
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.
After dinner, guests can spend the night in a smoking- or non-smoking-designated hotel room with either a king or two double beds.
The exact position of the Jebusite city is unknown; some authorities locate it on the western hill, now known as Zion; some on the eastern hill, afterwards occupied by the Temple and the city of David; while others consider it was a double settlement, one part being on the western, and the, other on the eastern hill, separated from one another by the Tyropoeon valley.
Eu has three buildings of importance - the beautiful Gothic church of St Laurent (12th and 13th centuries) of which the exterior of the choir with its three tiers of ornamented buttressing and the double arches between the pillars of the nave are architecturally notable; the chapel of the Jesuit college (built about 1625), in which are the tombs of Henry, third duke of Guise, and his wife, Katherine of Cleves; and the château.
The chief wheat lands are in Victoria, South Australia and New South Wales; the yield averages about 9 bushels to the acre; this low average is due to the endeavour of settlers on new lands to cultivate larger areas than their resources can effectively deal with; the introduction of scientific farming should almost double the yield.
At the southern end of the boulevard de la Republique is the square de la Republique, formerly the place Bresson, in which is the municipal theatre; at the other extremity of the boulevard is the place du Gouvernement, which is planted on three sides with a double row of plane trees and is the fashionable resort for evening promenade.
Abisares preferred to play a double game and wait upon events.
He is invoked with his double Mitra in some dozen hymns.
William's next quarrel was with Pope Alexander III., and arose out of a double choice for the vacant bishopric of St Andrews.
Their length is nearly equal to that of the longest pair of the ordinary form hitherto recorded, while the tip-to-tip interval is nearly double that of any other known specimen.
The interior is in the form of a basilica, the double aisles being borne by ancient columns, and contains ambones and a candelabrum of 1311, the former resting on columns supported by lions, and decorated with reliefs and coloured marble mosaic. The castle at the highest point of the town was erected in the 14th century.
A violent gust strikes the plate, which is driven back and carried by its own momentum far past the position in which a steady wind of the same force would place it; by the time the motion has reached the pen it has been greatly exaggerated by the springiness of the connexion, and not only is the plate itself driven too far back, but also its position is wrongly recorded by the pen; the combined errors act the same way, and more than double the real maximum pressure may be indicated on the chart.
For example, it has often been said that the extent to which their orchestral viola parts double the basses is due, partly to bad traditions of Italian opera, and partly to the fact that viola players were, more often than not, simply persons who had failed to play the violin.
But, when we look at the many passages in which the violas double the basses, we shall do well to consider whether there is room in the harmonic scheme for the violas to do anything else, and whether the effect would not be thin without them.
And when he writes in eight parts for a double chorus the two groups are seldom identioal.
He does not seem to have found any English trumpeters capable of playing as high parts as those of the German Clarin-Bldser, and his plan seems generally to get as many oboes and bassoons as could be procured to double the top and bottom of his string-band.
In his 5th symphony he introduced 3 trombones and extended both the upper and lower extremes of the windband by a piccolo and a double bassoon.
In Der Ring des Nibelungen Wagner specifies the proportions of the string-band as 16 first and 16 second violins, 12 violas, 12 violoncellos, 8 double basses.
In steam cranes it is usual to work all the motions from one double cylinder engine.
The warehouseman took all risks, paid double for all shortage, but no claim could be made .unless he had given a properly witnessed receipt.
This might be double, treble, fourfold, fivefold, sixfold, tenfold, twelvefold, even thirtyfold,, according to the enormity of the offence.
The form in general use on the British postal lines is the " Cordeaux screw," but the " Varley double cup " is still employed, especially by the railway companies.
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.
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.
It was then proposed to arrange a detector so that it was affected by the algebraic sum of the two oscillations, and by swivelling round the double receiving antennae to locate the direction of the sending station by finding out when the detector gave the best signal.
The interpunct is double with the Umbrian alphabet, single and medial with the Latin.
With the adoption of relays the signalling between the subscribers and the exchange became automatic, and, with the introduction of the principle of double and automatic supervision on the cord circuits, it became possible for the operators to tell at any instant the state of a connexion.
The Postmaster-General also agreed to lay underground wires for the company at an annual rental of L1 per mile of double wire in any local area in which the company was operating, but not in areas in which the municipalities had established exchanges.
The production of maize is, however, insufficient, and 208,719 tons were imported in 1902about double the amount imported in 1882.
The demands for reimbursement at par represented a sum of only 187,588 and the market value of the stock was hardly affected; while the saving to the Treasury was to be 800,000 per annum for the first five years and about double the amount afterwards.
The former total is more than double add the latter more than treble the sum in 1873, while there is an increase of 62% in the former and 26% in the latter over the totals for 1882.
We can distinguish (I) digestive endoderm, in the stomach, often with special glandular elements; (2) circu-, latory endoderm, in the radial and ring canals; (3) supporting endoderm in the axes of the tentacles and in the endodermlamella; the latter is primitively a double layer of cells, produced by concrescence OC-- = w.?"
The envelope is double, consisting of an external chitinous stratified shell, and an internal thin elastic membrane.
In the wall of the sack is a double layer of endoderm, the space between which is a continuation of the coelenteron.
From Hartlepool Hilda moved to Whitby, where in 657 she founded the famous double monastery which in the time of the first abbess included among its members five future bishops, Bosa, 'Etta, Oftfor, John and Wilfrid II.
The Leeward Islands are Tubai or Motuiti, a small uninhabited lagoon island, the most northern of the group; Marua or Maupiti - "Double Mountain," the most western; BolaBola or Bora-Bora; Huaheine; Raiatea or Ulietea (Spanish Princessa), the largest island of this cluster, and Tahaa, which approach each other very closely, and are encircled by one reef.
One of the most striking characters common to the two highest groups of plants, the Pteridophytes and Phanerogams, is the Vascular possession of a double (hydrom-leptom) conducting .s system, such as we saw among the highest mosses, YS em.
All the surviving forms, however, have a completely established double system with the specific characters alluded to, and since there is every reason to believe that the conditions of evolution of the primitive Pteridophyte must have been essentially similar to those of the Bryophytes, the various stages in the evolution of the conducting system of the latter (p. 732) are very useful to compare with the arrangements met with in the former.
It may be in the form of an albumen crystal sometimes associated with a more or less spherical bodygloboid-composed of a combination of an organic substance with a double phosphate of magnesium and calcium.
A double fertilization thus takes place.
The fundamental form-elements may be reduced to the six proposed by Professor Penck as the basis of his double system of classification by form and origin.'
In the region of the neck lateral strands pass through the transverse canal of the cervical vertebrae; but from the thoracic region onwards, where the cardiac branch to the heart is given off, each strand is double and the basal ganglia are successively connected with the next by a branch which runs ventrally over the capitulum of the rib, and by another which passes directly through the foramen or space formed between capitulum and tuberculum.
It was begun in 1369, and has double aisles, ambulatory and radiating chapels, and contains some finely carved woodwork.
Bredig point to the salt possessing the double formula.
They form many double salts and give a dark violet coloration with ferric chloride solution, this colour, however, gradually disappearing on standing, sulphur being precipitated.
Day and night, long processions of all classes and ages, headed by priests carrying crosses and banners, perambulated the streets in double file, reciting prayers and drawing the blood from their bodies with leathern thongs.
It may suffice to repeat that no domestic tragedy has ever taught with more effective simplicity and thrilling truthfulness the homely double lesson of the folly of selfishness and the mad rashness of crime.
The double river-systems of the Volga and Kama, the Ob and Irtysh, the Angara and Yenisei, the Lena and Vitim on the Arctic slope, and the Amur and Sungari on the Pacific slope, are instances.
The limits of the Russian Jurassic system may be represented by a line drawn from the double valley of the Sukhona and Vytchegda to that of the upper Volga, and thence to Kieff, with a wide gulf penetrating towards the N.W.
Now, you'd need double that magic to close both.
Her heart did double time as he straightened and looked her way again.
The double webs composing the sides of the fixed square shall be strictly parallel, and shall form a true square of exactly ten revolutions of the screw on the side.
The most carefully executed part is on the south and south-east, where the wall is decorated by a row of granite monoliths beneath which runs a double line of chevron ornament.
The presentation of some object of dread, for example, to the eye has or may have a double effect.
A special feature of his rule was the sending out of numerous cleruchies (q.v.), which served the double purpose of securing strategic points to Athens and converting the needy proletariate of the capital into owners of real property.
The exportation in I902 only reached about 45 million gallons (and even that is double the average), while an equally abundant vintage in France and Spain rendered the exportation of the balance of 1907 impossible, and fiscal regulations rendered the distillation of the superfluous amount difficult.
This serves a double purpose, bringing up from the soil continually a supply of the soluble mineral matters necessary for their metabolic processes, \vhich only enter the plant in solutions of extreme dilution, and at the same time keeping the plant cool by the process of evaporation.
It had six columns at each end (a double row in the front) and seventeen on each long side.
The United States of America, with a capital of £3,059,800,000 invested in its railways on the 30th of June 1906, was easily ahead of every other country, and in 1908 the figure was increased to £ 3,443, 02 7, 68 5, of which £2,636,569,089 was in the hands of the public. On a route-mileage basis, however, the capital cost of the British railway system is far greater than that of any other country in the world, partly because a vast proportion of the lines are double, treble or even quadruple, partly because the safety requirements of the Board of Trade and the high standards of the original builders made actual construction very costly.
The Locher rack, employed on the Mount Pilatus railway, where the steepest gradient is nearly I in 2, is double, with vertical teeth on each side, while in the Strub rack, used on the Jungfrau line, the teeth are cut in the head of a rail of the ordinary Vignoles type.
For instance, if the curve is of S-form, the point of danger is when the train enters the contra-flexure, and it is not an easy matter to assign the best superelevation at all points throughout the double bend.
Its width depends on the numbers of tracks and their gauge; for a double line of standard gauge it is about 25 ft., a space of 6 ft.
The resistance caused by the wind is very variable, and in extreme cases may double the resistance found from the formulae.
For the first installation a single line is prescribed, but the concessionaire must provide space and be prepared to double when required.
The outer walls of the double city contain an area of about 25 sq.
After the round shape was introduced, the one side was always inscribed with the figure of a ship's prow, and the other with the double head of Janus.
In his eighteenth year, while still a student in Edinburgh, he contributed two valuable papers to the Transactions of the same society - one of which, " On the Equilibrium of Elastic Solids," is remarkable, not only on account of its intrinsic power and the youth of its author, but also because in it he laid the foundation of one of the most singular discoveries of his later life, the temporary double refraction produced in viscous liquids by shearing stress.
The periodicity shows itself in the form of an exacerbation of the still continuing fever, and that exacerbation may take place twentyfour hours after the first onset, or the interval may be only half that period, or it may be double.
The arrangement used for the entrance is a wire cage with double doors.
Lord Auckland had the double mortification of seeing his policy a complete failure and of being superseded before his errors could be rectified.
It therefore took 140 years to double the numbers, while in 1841 the numbers of 1801 were more than doubled.
We may also notice the disruption of unsaturated acids at the double linkage into a mixture of two acids, when fused with potash.
The double election to the German throne in 141 o first brought Frederick into relation with Brandenburg.
In this instrument a considerable linear relative movement of the divided lens corresponds with a comparatively small separation of the double image, so that simple verniers reading to 6 1 0 in.
The menu features double cheeseburgers, quarter-pound burgers, regular burgers and cheeseburgers, grilled cheese, tuna on a bun, all beef franks and butterfly shrimp.
He wanted something a hell of a lot stronger—a double bourbon and leave the bottle but he knew the return trip to Parkside lay before him.
In the absence of its native records its relations with Palestine are not always clear, but it may be supposed that amid varying political changes it was able to play a double game.
Shrines of the Double Axes have been found in the palace of Cnossus itself, at Hagia Triada, and in a small palace at Gournia, and many specimens of the sacred emblem occurred in the Cave Sanctuary of Dicte, the mythical birthplace of the Cretan Zeus.
The discovery that the great Minoan foundation at Cnossus was at once a palace and a sanctuary of the Double Axe and its associated divinities has now supplied a striking and it may well be thought an overwhelming confirmation of this view.
This quarter of the palace shows the double axe sign constantly repeated on its walls and pillars, and remains of miniature wall-paintings showing pillar shrines, in some cases with double axes stuck into the wooden columns.
This gives access to a whole series of halls and private rooms (halls " of the Colonnades," " of the Double Axes," " Queen's Megaron" with bath-room attached and remains of the fish fresco, " Treasury " with ivory figures and other objects of art), together with extensive remains of an upper storey.
Near this domestic quarter was found a small shrine of the Double Axes, with cult objects and offertory vessels in their places.
The chest is of limestone coated with stucco, adorned with life-like paintings of offertory scenes in connexion with the sacred Double Axes of Minoan cult.
Pierre d'Ailly himself had not long before taken part in the drawing up of a letter to the king in which the advantages of this double abdication were set forth, but since then his zeal had seemed to cool a little.
The whole organ, having, as is thought but not known, this double origin, is termed a nephromixium.
The population of the double province is estimated at about 2,250,000.
This double identification enabled Cassiodorus to bring the favoured race into line with the peoples of classical antiquity, to interweave with their history stories about Hercules and the Amazons, to make them invade Egypt, to claim for them a share in the wisdom of the semi-mythical Scythian philosopher Zamolxis.
In plan it is a triangle, protected by a double moat, and has round towers at the angles.
From it rise double or triple ranges connected by cross-ridges and spined with outer spurs.
These double and triple ranges, which have a general elevation of 8500-10,000 ft., stretch from the south-east angle of the Black Sea, 400 m.
Some of the finer pears do not unite readily with the quince, and in this case double working is resorted to; that is to say, a vigorous-growing pear is first grafted on the quince, and then the choicer pear is grafted on the pear introduced as its foster parent.
The quantity imported in 1899 was double that in 1890, and quadruple that in 1885.
About 293 he installed his son Antiochus there as viceroy, the vast extent of the empire seeming to require a double government.
Giovanni Evangelista at the Frari, with its fore-court and screen adorned by pilasters delicately decorated with foliage in low relief, and its noble staircase whose double flights unite on a landing under a shallow cupola.
Railway connexion with Worcester, Lowell and Providence was opened in 1835; with Albany, N.Y., and thereby with various lines of interior communication, in 1841 (double track, 1868); with Fitchburg, in 1845; and in 1851 connexion was completed with the Great Lakes and Canada.
During the 18th century Kongsberg was more important than now, and contained double its present population.
The Distress for Rent Act 1737, however, enables a landlord to recover double rent from a tenant who holds over after having himself given notice to quit; while another statute in the reign of George II.
Options are single puts" or " calls ") or double (that Swaddles."
The gas wells of Pennsylvania indicate about double the pressure of those drilled in the Trenton limestone, 600-800 lb.
This piece of apparatus was introduced by William Morris in 1831, and consists of a long double link with closely-fitting jaws which, however, slide freely up and down.
The first three orders, which have a double muscular layer, external circular and internal longitudinal, are sometimes grouped together as the Dimyaria; the Heteronemertini, in which a third coat of longitudinal muscles arises outside the circular layer, are then placed in a second branch, the Trimyaria.
This is brought about by a double commissure, of which the ventral portion is considerably thicker than the dorsal, and which, together with the brain-lobes, constitutes a ring through which both proboscis and proboscidian sheath pass.
In addition to the nerves starting from the brain-lobes just now especially mentioned, there is a double apparatus which can hardly be treated of in conjunction with the sense organs, because its sensory functions have not been sufficiently made out, and which will therefore rather be considered along with the brain and central nervous system.
The more highly organized species have often very numerous eyes (Amphiporus, Drepanophorus), which are provided with a spherical refracting anterior portion, with a cellular " vitreous body," with a layer of delicate radially arranged rods, with an outer sheath of dark pigment, and with a separate nerve-twig each, springing from a common or double pair of branches which leave the brain as n.
Potash soap with the same reagent undergoes double decomposition - a proportion being changed into a soda soap with the formation of potassium chloride.
There is no separation of underlyes in potash soap, consequently the product contains the whole constituents of the oils used, as the operation of salting out is quite impracticable owing to the double decomposition which results from the action of salt, producing thereby a hard principally soda soap with formation of potassium chloride.
To the " Pelasgic " era may perhaps be referred (with Curtius and MilchhSfer) the immense double terrace on the north-eastern Pnyx.
On the north-west rock the caves known as the grottoes of Pan and Apollo were cleared out; these consist of a slight high-arched indentation immediately to the east of the Clepsydra and a double and somewhat deeper cavern a little farther to the east.
The Dipylon consists of an outer and an inner gate separated by an oblong courtyard and flanked on either side by towers; the gates were themselves double, being each composed of two apertures intended for the incoming and outgoing traffic. An opening in the city wall a little to the south-west, supposed to have been the Sacred Gate (iep t riAn), was in all probability an outlet for the waters of the Eridanus.
A Doric colonnade with a double row of columns was found to have extended along the base of the Acropolis for a distance of 54 yds.; behind it in a chamber hewn in the rock is the sacred well mentioned by Pausanias.
The Stoa consisted of a series of 21 chambers, probably shops, faced by a double colonnade, the outer columns being of the Doric order, the inner unfluted, with lotus-leaf capitals; it possessed an upper storey fronted with Ionic columns.
Numerous double chlorides are known, e.g.
At a cost of $7,200,000, the city completed in 1917 a municipal bridge of massive steel construction, double track and double deck, across the Mississippi.
During 1897 the death-rate for the whole province rose to sixty-nine per thousand, or double the average, while the birth-rate fell to twenty-seven per thousand.
Gerhardt found that reactions could be best followed if one assumed the molecular weight of an element or compound to be that weight which occupied the same volume as two unit weights of hydrogen, and this assumption led him to double the equivalents accepted by Gmelin, making H= 1, 0 =16, and C = 12, thereby agreeing with Berzelius, and also to halve the values given by Berzelius to many metals.
In the same year as Klaproth detected uranium, he also isolated zirconia or zirconium oxide from the mineral variously known as zircon, hyacinth, jacynth and jargoon; but he failed to obtain the metal, this being first accomplished some years later by Berzelius, who decomposed the double potassium zirconium fluoride with potassium.
At the same time Berzelius obtained the element, in an impure condition, by fusing silica with charcoal and iron in a blast furnace; its preparation in a pure condition he first accomplished in 1823, when he invented the method of heating double potassium fluorides with metallic potassium.
Of recent years the introduction of various organic compounds as precipitants or reagents has reduced the labour of the process; and advantage has also been taken of the fairly complex double salts which these metals form with compounds.
This view was modified by Liebig, who regarded ether as ethyl oxide, and alcohol as the hydrate of ethyl oxide; here, however, he was in error, for he attributed to alcohol a molecular weight double its true value.
Similarly he represented the reactions investigated by Liebig and Wehler on benzoyl compounds as double decompositions.
From similar investigations of valerianic acid he was led to conclude that fatty acids were oxygen compounds of the radicals hydrogen, methyl, ethyl, &c., combined with the double carbon equivalent C2.
It will be noticed that compounds containing two double linkages will have the same general formula as the acetylene series; such compounds are known as the " diolefines."
Hydrocarbons containing any number of double or triple linkages, as well as both double and triple linkages, are possible, and a considerable number of such compounds have been prepared.
If we accept Kekule's formula for the benzene nucleus, then we may expect the double linkages to be opened up partially, either by oxidation or reduction, with the formation of di-, tetra-, or hexa-hydro derivatives, or entirely, with the production of open chain compounds.
Therefore, according to Kekule, the double linkages are in a state of continual oscillation, and if his dynamical notion of valency, or a similar hypothesis, be correct, then the difference between the 1.2 and 1.6 di-derivatives rests on the insufficiency of his formula, which represents the configuration during one set of oscillations only.
A doubly linked pair of atoms is denoted by the sign A with the index corresponding to the side; if there are two pairs of double links, then indices corresponding to both sides are employed.
Thus denotes a tetrahydro derivative in which the double link occupies the side 1; 0 a dihydro derivative, the double links being along the sides i and 3.
From the fact that reduction products containing either one or two double linkages behave exactly as unsaturated aliphatic compounds, being readily reduced or oxidized, and combining with the halogen elements and haloid acids, it seems probable that in benzenoid compounds the fourth valencies are symmetrically distributed in such a manner as to induce a peculiar stability in the molecule.
When applied to benzene, a twofold conjugated system is suggested in which the partial valencies of adjacent atoms neutralize, with the formation of a potential double link.
Physico-chemical properties have also been drawn upon to decide whether double unions are present in the benzene complex; but here the predilections of the observers apparently influence the nature of the conclusions to be drawn from such data.
It was found that the results were capable of expression by the empirical relation CaH2b= 104.3b+49'09m+105.47n, where C a H 2b denotes the formula of the hydrocarbon, m the number of single carbon linkings and n the number of double linkings, m and n being calculated on the Kekule formulae.
These bands are due to molecular oscillations; Hartley suggests the carbon atoms to be rotating and forming alternately single and double linkages, the formation of three double links giving three bands, and of three single links another three; Baly and Collie, on the other hand, suggest the making and breaking of links between adjacent atoms, pointing out that there are seven combinations of one, two and three pairs of carbon atoms in the benzene molecule.
The former, based on Kekule's symbol for benzene, explains the decompositions and syntheses of the ring, but the character of naphthalene is not in keeping with the presence of five double linkages, although it is more readily acted upon than benzene is.
During recent years an immense number of ringed or cyclic compounds have been discovered, which exhibit individual characters more closely resembling benzene, naphthalene, &c. than purely aliphatic substances, inasmuch as in general they contain double linkages, yet withstand oxidation, and behave as nuclei, forming derivatives in much the same way as benzene.
By reduction, the double linkages become saturated, and compounds result which stand in much about the same relation to the original nucleus as hexamethylene does to benzene.
In general, therefore, it may be considered that the double linkages are not of exactly the same nature as the double linkage present in ethylene and ethylenoid compounds, but that they are analogous to the potential valencies of benzene.
The centric hypothesis has been applied to these rings by Bamberger and others; but as in the previous rings considered, the ordinary (3) (4) (5) representation with double and single linkages generally represents the syntheses, decompositions, &c.; exceptions, however, are known where it is necessary to assume an oscillation of the double linkage.
Thus a double bond of oxygen, as in the carbonyl group CO, requires a larger volume than a single bond, as in the hydroxyl group - OH, being about 12.2 in the first case and 7.8 in the second.
An ethylenic or double carbon union in the aliphatic hydrocarbons has, apparently, the same effect on the boiling-point as two hydrogen atoms, since the compounds C 0 H 2 „ +2 and CoH2n boil at about the same temperature.
An important connexion between heats of combustion and constitution is found in the investigation of the effect of single, double and triple carbon linkages on the thermochemical constants.
It contains four independent constants; two of these may be calculated from the heats of combustion of saturated hydrocarbons, and the other two from the combustion of hydrocarbons containing double and triple linkages.
By experiment it is found that the thermal effect of a double bond is much less than the effect of two single bonds, while a triple bond has a much smaller effect than three single bonds.
Thomsen deduced that a single bond between a carbon and a nitrogen gramme-atom corresponds to a thermal effect of 2.77 calories, a double bond to 5.44, and a treble bond to 8.31.
He also showed how changes in constitution effected dispersions to a far greater extent than they did refractions; thus, while the atomic dispersion of carbon is 0.039, the dispersions due to a double and treble linkage is 0.23 and 0.19 respectively.
It also acts as a chromogenic centre when double bonds or ethylenic linkages are present, as in fluorene ketone or fluorenone.
Although the theories of Meyer and Hewitt do not explain (in their present form) the behaviour of anthranilic acid, yet Hewitt has shown that his theory goes far to explain the fluorescence of substances in which a double symmetrical tautomerism is possible.
In the case of separation from solutions, either by crystallization or by precipitation by double decomposition, the temperature, the concentration of the solution, and the presence of other ions may modify the form obtained.
It may happen that the crystals do not form double salts, and are only miscible in certain proportions.
An important distinction separates true mixed crystals and crystallized double salts, for in the latter the properties are not linear functions of the properties of the components; generally there is a contraction in /10.591 volume, while the re fractive indices and other physical properties do not, in general, obey the additive law.
In keeping with this, her festivals at Naxos present a double character; the one, full of mourning and sadness, represents her death or abandonment by Theseus, the other, full of joy and revelry, celebrates her awakening from sleep and marriage with Dionysus.
In the case of certain provinces, possibly in the empire generally, Alexander established a double control.
Alexander carried on a double policy, always ready to seize opportunities to aggrandize his family.
The tail is thick and bushy, the feet and legs particularly strong, and there is usually a double dew-claw on each hind limb.
Friends have always held that the attempt to enforce truthspeaking by means of an oath, in courts of law and elsewhere, tends to create a double standard of truth.
Formerly the system was double, the men and women meeting separately for their own appointed business.
Hence arose a double negotiation between him and Eugenius IV.
Not a few of the slabs, it is discovered, have done double duty, bearing a pagan inscription on one side and a Christian one on the other.
Explorations conducted in the cemetery of Domitilla in 1897-1898 brought to light a fine double crypt with frescoes representing Christ seated between six male and female saints; also an inscription relating to a new saint (Eulalius) in a cubiculum of the 3rd century.
A large number of representatives of the group are known from both the Old and the New World; specialization displaying itself in the later ones in the development of dermal horns over the nasal bones, either in laterally placed pairs as in some of the early forms, or in the median line, either single or double.
We have already seen that the Sephiric decade or the archetypal man, like Christ, is considered to be of a double nature, both infinite and finite, perfect and imperfect.
The prefect has to a certain extent a double character and two series of functions.
The senate contains four members from each province, chosen for eight years by a provincial electoral board, which consists of the provincial councilmen plus a double number of electors (half of them paying high taxes) who are selected at a special election by their fellow citizens.
The basis of the system adopted was the double standard with a fixed relation of I to 15.09, and free coinage.
Elsewhere, too, the Ottoman arms were victorious; in February the Venetians suffered a double defeat in the roadstead of Chios, and the island fell into the hands of the Turks.
But the Prussians attacked at the old regulation speed of seventy-five paces to the minute, and the French manoeuvred at the quick or double of i 20 or 150.
So desperate had been their resistance that the Prussians unanimously stated Davout's strength at double the actual figure.
Where formerly 15,000 men to the mile of front had been considered ample for the occupation of a position or the execution of an attack, double that number now often proved insufficient, and their front was broken before reinforcements could arrive.
During the existence of the Temple there was a double celebration of the Passover, a series of stipulated sacrifices being offered during the seven days in the Temple, details of which are given in Num.
They teach further the solution of problems leading to equations of the first and second degree, to determinate and indeterminate equations, not by single and double position only, but by real algebra, proved by means of geometric constructions, and including the use of letters as symbols for known numbers, the unknown quantity being called res and its square census.
In order to meet the double purposes of government and trade,.
The oxides are then converted into double sulphates which are separated from each other by repeated fractional crystallization or by fractional precipitation with ammonia or some other base.
In well-developed shoots the buds are generally double, or rather triple, a wood bud growing between two fruit buds; the shoot must be cut back to one of these, or else to a wood bud alone, so that a young shoot may be produced to draw up the sap beyond the fruit, this being generally desirable to secure its proper swelling.
Porphyritic crystals often contract less than the surrounding glass, which accordingly becomes strained, and in polarized light may show a weak double refraction in a limited area surrounding the crystal.
The volume of the hydrogen was about double that of the oxygen, and, since this is the ratio in which these elements are combined in water, it was concluded that the process con sisted essentially in the decomposition of water.
It is possible to distinguish between double salts and salts of compound acids.
The salt must therefore be derived from an acid, chloroplatinic acid, H 2 PtC1 6, and have the formula Na 2 PtC1 6, the ions being Na and PtCls", for if it were a double salt it would decompose as a mixture of sodium chloride and platinum chloride and both metals would go to the cathode.
If two solutions containing the salts AB and CD be mixed, double decomposition is found to occur, the salts AD and CB being formed till a certain part of the first pair of substances is transformed into an equivalent amount of the second pair.
The tests for a salt, potassium nitrate, for example, are the tests not for KNO 3, but for its ions K and NO 3, and in cases of double decomposition it is always these ions that are exchanged for those of other substances.
By general agreement among the powers the command was entrusted to Codrington, and the allied force consisted of three British, four French and four Russian sail of the line, if the French admiral's flagship the "Sirene" (60), which was technically "a double banked frigate," be included.
Double texture goods are made by uniting the rubber surfaces of two pieces of the coated material.
Examples are the Ob and the Irtysh, the Yenisei and the Angara (itself a double river formed by the Angara and the Lower Tunguzka), the Lena and the Vitim, the Argun and the Shilka, while the Amur in its turn receives a tributary as large as itself - the Sungari.
The coast-line has few indentations, the chief being the double gulf of the Ob and the Taz, separated from the Sea of Kara by an elongated peninsula (Samoyede), and from the bay of the Yenisei by another.
The double bay of Gizhiga and Penzhina, as well as that of Taui, would be useful as harbours were they not frozen seven or eight months in the year and persistently shrouded in dense fogs in summer.
Occlusor muscle - its double origin (i.) is derived from the is shown.
This was contained implicitly in the ordonnance of 1439, which at the same time suppressed the seigniorial taille, as competing too closely with the royal taille by imposing a double burden on the taxpayer.
The ovary is double, and the oviducts open by a median ventral pore about the middle of the body; in this region there is a second swelling.
Ulm cathedral has double aisles and a pentagonal apsidal choir, but no transepts.
Most kettles at present hold 30 tons of lead; some, however, have double that capacity.
It is not likely, as many scholars have thought, that Akkad was ever used geographically as a distinctive appellation for northern Babylonia, or that the name Sumer denoted the southern part of the land, because kings who ruled only over Southern Babylonia used the double title "king of Sumer and Akkad," which was also employed by northern rulers who never established their sway farther south than Nippur, notably the great Assyrian conqueror Tiglath pileser III.
The standard induction in reference to determinations of hysteresis is generally taken as 2500, while the loss is expressed in watts per lb at a frequency of ioo double reversals, or cycles, per second.
A little instrument, supplied by Hartmann and Braun, contains a short length of fine bismuth wire wound into a flat double spiral, half an inch or thereabouts in diameter, and attached to a long ebonite handle.
These are preferably made slightly wedge-shape, to avoid the inconvenience resulting from multiple internal reflections, and they must necessarily be rather thin, so that double refractions due to internal strain may not exert a disturbing influence.
The various comparisons previously made between the structure of Limulus and the Eurypterines on the one hand, and that of a typical Arachnid, such as Scorpio, on the other, had been vitiated by erroneous notions as to the origin of the nerves supplying the anterior appendages of Limulus (which were finally removed by Alphonse Milne-Edwards in his beautiful memoir (6) on the structure of that animal), and secondly by the erroneous identification of the double sternal plates of Limulus, called " chilaria," by Owen, with a pair of appendages (7).
Scorpio is here provided with a single or double pair of renal excretory tubes, which have been identified by earlier authors with the Malpighian tubes of the Hexapod and Myriapod insects.
Monomeniscous eyes with a double (really triple) cell-layer formed by invagination, as in the Eu-arachnida, are present.
Lateral eyes also may be present, arranged in lateral groups, and having a single or double cell-layer beneath the lens.
This double cultivation of his scientific powers had the happiest effect on his subsequent work; for the greatest achievements of Riemann were effected by the application in pure mathematics generally of a method (theory of potential) which had up to this time been used solely in the solution of certain problems that arise in mathematical physics.
Columbium hydride, CbH, is obtained as a greyish metallic powder, when the double fluoride, CbF 5, 2 KF, is reduced with sodium.
It forms many double salts with other metallic fluorides.
The exports are, on the average, over one million sterling, and imports about double in value.
Noblemen dwelling within the walls of the towns were especially exempted from all civic burdens, while every burgess who bought an extra-mural estate was made to pay double for the privilege.'
Less reprehensible, though equally self-seeking, were his dealings with the emperor, which aimed at a family alliance between the Jagiellos and the Habsburgs on the basis of a double marriage between the son and daughter of Wladislaus, Louis and Anne, and an Austrian archduke and archduchess; this was concluded by the family congress at Vienna, July 22, 1515, to which Sigismund I.
The dismissal of Wallenstein, which is often attributed to the work of Father Joseph, Richelieu's envoy to the diet of Regensburg in July and August of 1630, was due rather to the fears of the electors themselves, but it was of double value to Richelieu when his Swedish ally marched south.
The power of the collective episcopate to maintain Catholic unity was disproved long before it was overshadowed by the centralized authority of Rome; before the Reformation, its last efforts to assert its supremacy in the Western Church, at the councils of Basel and Constance, had broken down; and the religious revolution of the 16th century left it largely discredited and exposed to a double attack, by the papal monarchy on the one hand and the democratic Presbyterian model on the other.
Linnaeus adopted Ray's conception of species, but he made species a practical reality by insisting that every species shall have a double Latin name - the first half to be the name of the genus common to several species, and the second half to be the specific name.
Very different was Valdemar's second conference with Barbarossa, on the banks of the Eider, in 1182, when the two monarchs met as equals in the presence of their respective armies, and a double marriage was arranged between two of Valdemar's daughters and two of the emperor's sons.
Let us now consider the distribution of brightness in the image of a double line whose components are of equal strength, and at such an angular interval that the central line in the image of one coincides with the first zero of brightness in the image of the other.
We conclude that a double line cannot be fairly resolved unless its components subtend an angle exceeding that subtended by the wave-length of light at a distance equal to the horizontal aperture.
If the angular interval between the components of a double line be half as great again as that supposed in the figure, the brightness midway between is 1802 as against 1.0450 at the central lines of each image.
If the angle subtended by the components of a double line be twice that subtended by the wave-length at a distance equal to the horizontal aperture, the central bands are just clear of one another, and there is a line of absolute blackness in the middle of the combined images.
Theory and experiment alike prove that a double line, of which the components are equally strong, is better resolved when, for example, one-sixth of the horizontal aperture is blocked off by a central screen; or the rays quite at the centre may be allowed to pass, while others a little farther removed are blocked off.
In estimating theoretically the resolving power on a double star we have to consider the illumination of the field due to the superposition of the two independent images.
If the angular interval between the components of a double star were equal to twice that expressed in equation (15) above, the central disks of the diffraction patterns would be just in contact.
The latter element enters only when it is a question of recognizing the duplicity of a double star, or of distinguishing detail upon the surface of a planet.
According to our former standard, this gives the smallest difference of wave-lengths in a double line which can be just resolved; and we conclude that the resolving power of a grating depends only upon the total number of lines, and upon the order of the spectrum, without regard to any other considerations.
In the case of the D lines the value of Sa/X is about 1/1000; so that to resolve this double line in the first spectrum requires moo lines, in the second spectrum 500, and so on.
If it exceed the double of the value necessary for black bands, there is again no overlapping and consequently no interference.
Now it is evident that the force in question, supposed to act upon the positive half only of the medium, produces just double of the effect that would be caused by the same force if the medium were undivided, and on the latter supposition (being also localized at a point) it comes under the head already considered.
Peligot's results, though called in question by Berzelius, have been amply confirmed by all subsequent investigators; only now, on theoretical grounds, first set forth by Mendeleeff, we double Peligot's atomic weight, so that U now signifies 240 parts of uranium, while UO 3 stands as the formula of the yellow oxide, and UO 2 as that of Berzelius's metal.
With hydroflouric acid it yields uranous fluoride, UF 4, which forms double salts of the type MF UF 4.
It forms double salts with metallic chlorides and with the hydrochlorides of organic bases.
A considerable legend has attached itself to Nicholas through the persistent but mistaken identification of him with the mysterious "Friend of God from the Oberland," the "double" of Rulman Merswin, the Strassburg banker who was one of the leaders of the 14th-century German mystics known as the Friends of God.
It combines readily with alkaline and other chlorides to form double salts, e.g.
The Pharaoh's characteristic crown (or crowns) symbolized his royal domains, the sacred uraeus marked his divine ancestry, and he sometimes appeared in the costume of the gods with their fillets adorned with double feathers and horns.
The chiton, xcrcww, was formed by sewing together at the sides two pieces of linen, or a double piece folded together, leaving spaces at the top for the arms and neck, and fastening the top edges together over the shoulders and upper arm with buttons or brooches; more rarely we find a plain sleeveless chiton.
The Kvp3a61a, or Kibapts, was a high-pointed hat of Persian origin, as was also the ncipa, which served the double purpose of an ornament and a covering for the head.
The military skill of Gylippus enabled the Syracusan militia to meet the Athenian troops on equal terms, to wrest from them their fortified position on Plemmyrium, which Nicias had occupied as a naval station shortly after Gylippus's arrival, and thus to drive them to keep their ships on the low beach between their double walls, to take Labdalum, an Athenian fort on the northern edge of Epipolae, and make a third counter-work right along Epipolae in a westerly direction, to the north of the circular fort.
The line is double track and the rope constantly in motion, the cars being attached at intervals through its length by clips or clutches; the loaded cars move in one direction, the empties in the other.
The engine is direct-acting, the drums making one revolution for each double stroke.
In geared hoists the drums. are on a separate shaft, driven from the crank-shaft by tooth or friction gearing, and make one revolution for, say, 4 or 5 double strokes.
The existence of internal strains in glass can be readil y recognized by examination in polarized light, any signs of double refraction indicating the existence of strain.
If before this application of the molten glass the metallic leaf, whilst resting on the thin film of blown glass, was etched with a sharp point, patterns, emblems, inscriptions and pictures could be embedded and rendered permanent by the double coating of glass.
The base is double but the inner lining has an opening in the centre.
Negative values of n must be interpreted by a streaming motion on a parallel plane at a level slightly different, as on a double Riemann sheet, the stream passing from one sheet to the other across a cut SS' joining the foci S, S'.
This double method of writing words arises from the circumstance that the cuneiform syllabary is of non-Semitic origin, the system being derived from the non-Semitic settlers of the Euphrates valley, commonly termed Sumerians (or Sumero-Akkadians), to whom, as the earlier settlers, the origin of the cuneiform script is due.
The fortifications of the citadel have an elaborate double gate with flanking towers.
Hence in the latest designs for large factories it has been proposed that as much normal juice as can be extracted by double crushing only shall be treated by itself, and that the megass shall then be soused with twice as much water as there is juice remaining in it; after which, on being subjected to a third crushing, it will yield a degraded juice, which would also be treated by itself.
It is found that in reducing the juice of these two qualities to syrup, fit to pass to the vacuum pans for cooking to crystals, the total amount of evaporation from the degraded j uice is about half that required from the normal juice produced by double crushing.
Extraction of cane juice by diffusion (a process more fully described under the head of beetroot sugar manufacture) is adopted in a few plantations in Java and Cuba, in Louisiana Etr cti o n and the Hawaiian Islands, and in one or two factories y f i in Egypt; b u t hitherto, except under exceptional conditions (as at Aska, in the Madras Presidency, where the local price for sugar is three or four times the London price), it would not seem to offer any substantial advantage over double or triple crushing.
The best results from extraction by diffusion have been obtained in Java, where there is an abundance of clear, good water; but in the Hawaiian Islands, and in Cuba and Demerara, diffusion has been abandoned on several well mounted estates and replaced by double and triple crushing; and it is not likely to be resorted to again, as the extra cost of working is not compensated by the slight increase of sugar produced.
But this competition among inventors, whatever the incentive, has not been without benefit, because to-day, by means of very simple improvements in details, such as the addition of circulators and increased area of connexions, what may be taken to be the standard type of multiple-effect evaporator (that is to say, vertical vacuum pans fitted with vertical heating tubes, through which passes the liquor to be treated, and outside of which the steam or vapour circulates) evaporates nearly double the quantity of water per square foot of heating surface per hour which was evaporated by apparatus in use so recently as 1885 - and this without any increase in the steam pressure.
That evaporation in vacuo, in a multiple-effect evaporator, is advantageous by reason of the increased amount of sugar obtained from a given quantity of juice, and by reason of economy of fuel, there is no doubt, but whether such an apparatus should be of double, triple, quadruple or quintuple effect will depend very much on the amount of juice to be treated per day, and the cost of fuel.
Earthy matter and other matter precipitated and fallen on the copper double bottom may be dislodged by a slowly revolving scraper - say every twelve hours - and ejected through the bottom discharge cock; and thus the heating surface of the copper bottom will be kept in full efficiency.
It contains several small lakes, and two of large size, Bey-Sheher Lake, the ancient Karalis, and the double lake now called the Egerdir Geul, of which the ancient name was Limnai.
There are perfect cleavages parallel to the rhombohedral faces, and the crystals exhibit a strong negative double refraction, like calcite.
With ammonia and alkaline bromides and iodides double salts are formed.
Zinc sulphate, like magnesium sulphate, unites with the sulphates of the potassium metals and of ammonium into crystalline double salts, ZnS04 R2S04-+-6H20, isomorphous with one another and the magnesium salts.
When the latter desired to double the number of the equestrian centuries, Navius opposed him, declaring that it must not be done unless the omens were propitious, and, as a proof of his powers of divination, cut through a whetstone with a razor.
Jebel Shammar, from which the northern district of Nejd takes its name, is a double range of mountains some 20 m.
Sainte Claire Deville working independently obtained aluminium by the electrolysis of the fused double sodium aluminium chloride.
Other churches are the Gothic church of the Holy Ghost; the churches of St Severin, of St Paul and of St Gertrude; the double church of St Salvator; the Romanesque church of the Holy Cross; the pilgrimage church of Our Lady of Succour (Mariahilf); the church of the hospital of St John; and the Romanesque Votiv Kirche.
They are all strong bases, readily forming salts with the mineral acids and double salts with the chlorides of gold, platinum and mercury.
Aromatic Amines.-The aromatic amines in some respects resemble the aliphatic amines, since they form salts with acids, and double salts with platinum chloride, and they also distil without decomposition.
The change from the double standard was effected without any noticeable disturbance in commercial affairs, but this was in part due to the precaution of making the British pound sterling legal tender in the republic and establishing the legal equivalent between gold and silver at 10 soles to the pound.
Although the double standard was in force, gold was practically demonetized by the monetary reform of 1872 because of the failure to fix a legal ratio between the two metals.
In the Diversarum Speculationum Mathematicarum et Physicarum (1585), by the Venetian Giovanni Battista Benedetti, there is a letter in which he discusses the simple camera obscura and mentions the improvement some one had made in it by the use of a double convex lens in the aperture; he also says that the images could be made erect by reflection from any plane mirror.
In his later book, Dioptrice (1611), he fully discusses refraction and the use of lenses, showing the action of the double convex lens in the camera obscura, with the principles which regulate its use and the reason of the reversal of the image.
Napoleon had here double the force of the allies; Kutusov, however, displayed great energy, changed front to his right and called up his reserves.
The flowers are bell-shaped, yellow or red, and in some of the forms double.
There are a few named varieties, but the most generally grown are the single and double yellow, and the single and double red,the single red having also two variegated varieties, with the leaves striped respectively with white and yellow.
The new additions to the harbour, which are situated at the south end, were designed to give more than double the receiving capacity of the port, and were estimated to cost £3,625,000.
A few months later the great reverse of Chickamauga created an alarm in the North commensurate with the elation that had been felt at the double victory of Vicksburg and Gettysburg, and Grant was at once ordered to Chattanooga, to decide the fate of the Army of the Cumberland in a second battle.
Prisms are of great value in cases of double vision due to a slight tendency to squinting, caused by weakness or over-action of the muscular apparatus of the eyeball.
In cases of myopia or short-sight owing to weakness of the internal recti muscles, the eyes in looking at a near object, instead of converging, tend to turn outwards, and so double vision results.
If a suitable prism is placed in front of the eyes the double vision may be prevented.
In the slighter forms no inconvenience may result; but in higher degrees prolonged work is apt to give rise to aching and watering of the eyes, headache, inability to read or sew for any length of time, and even to double vision and internal strabismus.
They are thus the double key of The double Comte's systematization of the philosophy of all the key of sciences from mathematics to physiology, and his positive analysis of social evolution, which is the base of philo= sociology.
The large double doors of cedar wood, covered with bronze showing a geometric interlaced pattern, have been compared with those of Ghiberti at the Baptistery of Florence.
The Almoravides reigned sixty-five years, when, after holding Agadir four years against the enemy, they were overcome by the Almohades, who massacred the inhabitants, rebuilt, enlarged and repeopled the ruined town, and built a wall (1161) surrounding the double town.
In December 1831 Gladstone crowned his career by taking a double first-class.
His flashing eyes were deep-set, and in colour resembled the onyx with its double band of brown and grey.
It is a double arch, and above it are two orders of smaller arcades.
Some weeks afterwards high feast was held on the occasion of the double marriage of the king's daughter Elizabeth with the king of Spain, and of his sister Margaret with the duke of Savoy.
There is a double crater, the outer being almost complete.
The principal faade of the temple is filled in one, two or three compartments with hinged doors, variously ornamented and folding outwards, sometimes in double folds.
The lines are single, for the most part; and as the embankments, the cuttings, the culverts and the bridge-piers have not been constructed for a double line, any change now would be very costly.
Of persons aged sixteen or over, the number of males was almost double the number of females.
Auric cyanide, Au(CN) 3, is not certainly known; its double salts, however, have been frequently described.
Oxy-salts of gold are almost unknown, but the sulphite and thiosulphate form double salts.
Sluices are often made double, and they are usually cleaned up - that is, the deposit rich in gold is removed from them - once a week.
The roasted mineral, slightly moistened, is introduced into a vat made of stoneware or pitched planks, and furnished with a double bottom.
Johanan solaced his disciples on the fall of the Temple by the double thought that charity could replace sacrifice, and that a life devoted to the religious law could form a fitting continuation of the old theocratic state.
Hardy that the "double aspect of Trajan's rescript, which, while it theoretically condemned the Christians, practically gave them a certain security," explains "the different views which have since been taken of it; but by most of the church writers, and perhaps on the whole with justice, it has been regarded as favourable and as rather discouraging persecution than legalizing it" (Pliny's Correspondence with Trajan, 63, 210-217).
The double name AbramAbraham has even suggested that two personages have been combined in the Biblical narrative; although this does not explain the change from Sarai to Sarah.
In his double capacity as governor of the Territory and commanding officer of the army, reasonably certain of his hold on Jefferson, and favourably situated upon the frontier remote from the centre of government, he attempted to realize his ambition to conquer the Mexican provinces of Spain.
A breakwater was therefore planned on the Monarch shoal, to double the available anchorage area and increase the frontage of deep-water wharves available in all weathers.
These compounds closely resemble the trichloride in their methods of preparation and their properties, forming oxyhaloids with water, and double compounds with ammonia, &c.
For, since the commencement of the era is placed at an intermediate period of history, we are compelled to resort to a double manner of reckoning, backward as well as forward.
In the end of July 1567 the earl of Moray, Mary's brother, passing through London from France, told de Silva, as de Silva reported to his government, that there was proof of Mary's guilt in a letter of three double sheets of paper signed by her.
It will readily be understood, for example, that a copy will be halfsize if the distance of the object from the instrument is double the distance of the instrument from the copy.
In the 5th and following centuries the north portion was Teutonized, first by the Ostrogoths, mainly by the Baiouarii, but the Teutonic Langobardi who pressed up from the south became Romanized themselves, so that the double character of the inhabitants of the land appears quite early.
It would appear that to Servington Savary is due the first invention of a micrometer for measurement by double image.
In 1812 Bessel measured with it the angle between the components of the double star 61 Cygni and observed the great comet of 1811.
The first application of the divided object-glass and the employment of double images in astronomical measures is due to Savary in 1743.
To Bouguer in 1748 is due the true conception of measurement by double image without the auxiliary aid of a filar micrometer, viz.
Struve also points out that by attaching a fine scale to the focusing slide of the eye-piece, and knowing the coefficient of expansion of the metal tube, the means would be provided for determining the absolute change of the focal length of the object-glass at any time by the simple process of focusing on a double star.
Simi larly the prism may be used for the study and elim- " ination of personal errors depending on the angle made s by a double star with the vertical.
This lens is divided and mounted like a heliometer objectglass; the separation of the lenses produces the required double image, and is measured by a screw.
Dawes found the best method for the purpose in question was to limit the aperture of the object-glass by a diaphragm having a double circular aperture, placing the line joining the centres of the circles approximately in the position angle under measurement.
Dawes successfully employed the double circular aperture also with Amici's micrometer.
He, however, successfully employed the instrument in measuring double stars, so close as I" or 2", and using a power of 300 diameters, with results that agreed satisfactorily amongst themselves and with those obtained with the filar micrometer.
If Struve had employed a properly proportioned double circular diaphragm, fixed symmetrically with the axis of the telescope in front of the divided lens and turning with the micrometer, it is probable that his report on the instrument would have been still more favourable.