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A sapientibus vita in unâ virtute posita est. 8. Felicitatem pono in the act of combustion are oils, wax, tallow, spermaceti, paraffin, Dei amore. 9. Estne tibi cupiditas verum inveniendi? 10. Natura rock oil, and gas from coal, rosin, wood, or other suitable organic animis talem cupiditatem ingenuit omnibus. 11. Et divitibus et pau. matter. The extraordinary light-giving agents are oxygen and peribus amor sui ingenitus est. 12. Fratres tui iræ succubuerunt, et, hydrogen gases, burning and directed on to a ball of lime; the consertis manibus, pugnaverunt. 13. Pater meus progredietur urbem combustion of the metal magnesium in air, or of phosphorus in obessurus. 14. Copiæ progressi sunt domosque diripiunt.

oxygen gas; the voltaic battery, in which zinc is consumed and APPLICATIONS OF "COLO."

two charcoal points ignited by the current of electricity; the 1. The steward has been appointed for the sake of tilling the land.

magneto-electric machine, worked by steam power, and thereNot all fields which are tilled are fruit-bearing.

fore consuming coal instead of zinc, to produce the electric light.. 2. Inhabit the city, O my Rufus, and live in that light (distinguished

The predominating elements in the ordinary light-giving subplace). 3. Thou, Jupiter, who carest for and nourishest the race of men.

stances are carbon and hydrogen, and when any of them are Let it be your object to take care of your breast by noble means,

subjected to destructive distillation, these elements unite and 4. He cultivated the study of philosophy from early youth.

form two important compounds, the one called olefiant gas, and 5. Now clearly I am able to pursue neither that diet nor that way the other light carburetted hydrogen; and if coal is used, a of life.

number of other compounds are also produced. The distilla6. I love you, because you regard me.

tion of coal is easily conducted on a small scale by placing By whom we seem to be carefully regarded and esteemed.

some roughly-powdered coal in an old pistol barrel, and having 7. What is it you say why the gods should be worshipped by men, plugged the touch-hole, and fitted a piece of pewter pipe with when the gods not only do not look upon men, but, indeed, care some plaster of Paris to the muzzle of the barrel, the latter may nothing about them? We ought both to adore and worship these gods.

be thrust between the bars of an open grate in which a brisk

fire is burning. In the first instance, moisture only distils over; EXERCISE 149.-LATIN-ENGLISH.

at a dull red-heat more water, a thick smoke, and but little or no 1. Regard for our body is implanted in us. 2. Where there is no gas; and it is only when a full cherry red-heat is attained-viz., sowing, there is no reaping. 3. Everything which was gross and a temperature of 1500°—that gas of high illuminating power corporeal, God made subject to the mind. 4. You have put down the is evolved. The crude gas being very impure, and containing reproaches and hatred of ill-disposed persons by your way of living. 5. The governor, Probus, planted the Golden mountain, near Mesiá, many things useless for illuminating agents, is subjected at the with vines. 6. The battle having begun, all places far and wide were

gas-works to purification, and even then does not consist only of strewn with weapons, armour, and dead bodies. 7. The consciousness compounds of carbon and hydrogen, but of hydrogen and other of despised virtue torments the wicked man. 8. Tell me why you have gaseous bodies. Dr. Letheby states, that coal gas may contain despised my counsel. 9. Listen, boy, your mother asks you why you from 25 to 50 per cent. of hydrogen gas, 35 to 52 per cent. of have forgotten to eat the buttered bread. 10. Loveliness (venustas) and light carburetted hydrogen and from 3 to 20 per cent. of beauty of person are not separated from health. 11. Cato addressed olefiant gas, and other hydro-earbons mixed with gases, such as. the people,

carbonic oxide, carbonic acid, cyanogen, ammonia, oxygen, EXERCISE 150.--ENGLISH-LATIN.

nitrogen, some aqueous vapour, and sulphur compounds. 1. Insitus est pectore liberorum nostrorum amor. 2. Meum con The only gases required out of this complex mixture are the silium spreverunt. 3. Consilium meum ab illis spretum est. 4. Sper compounds of carbon and hydrogen; and hence tallow, oils, wax, oblinent malis moribus. 7. Boni a malis secernendi sunt. 8. Pueros paraffine, turpentine, etc., used in candles and lamps, which are secrevi a puellis. 9. Cicero concionabitur. 10. Victoria regnante, miniature gas-works, yield a gas purer than the heterogeneous one Britanniæ potentia mirum in modum crevit. 11. Amicitia nostra derived from the distillation of coal. That a burning candle cum ætate crescet.

is a gas-maker is shown by blowing out a lighted composite

candle; a column of smoky gas ascends from the wick, which RECREATIVE SCIENCE.-II.

may be set on fire by holding a burning match at the top of

the column, when the flame runs down in a very curious manner ARTIFICIAL ILLUMINATION.

to the hot wick, and the candle is re-lighted. In a candle the The imitative faculty of man has, no doubt, prompted many retort is the wick, and this when first lighted barns down until notable discoveries which might probably never have been con- the heat reaches that part which is saturated with the tallow, ceived if Nature had not first suggested the primary idea. The composite, or wax : at this point destructive distillation comgreat lamp, the sun, burning and shining continually in the mences; the heat from the increased combustion now melts more heavens during the day would, by its very absence at night, of the solid material; and this, being drawn up into the wick by even to the most ignorant of sayages, suggest the thought of capillary attraction, is decomposed in its turn, and furnishes making a substitute, an imitation-in short, an artificial fire or fresh gas for combustion. In the above case the gas is illumination.

generated and burnt directly it is produced. With coal gas the Thus the primary idea realised by a rude fire of wood would generating process is over, and the gas only is burnt. Capillary be gradually worked out, the commencement being made with a attraction (from capillus, a hair), in allusion to the nature of pine torch, and the light-giving agent elaborated, until the con- some of the bodies having this property, is an illustration of the struction of the most elegant and

perfect lamp was attained. adhesion between solids and liquids. If a slice of salt is cut The ancients, according to Fortunio Liceti, do not appear to out of the solid block, and placed upright in a plate containing have been satisfied with a mere lamp. Their ambition appears a little ink, the latter soon runs up the white salt, and first to have led them to suppose that the sun could be more closely attacking it by capillary attraction, the liquid is introduced into imitated, and that lamps might be made perpetual. Liceti the pores, the salt partiy dissolves, and the remainder crumbles contended vigorously for the possibility of constructing a down into the plate. "perpetual lamp," and he quotes in support of his arguments A bit of cane, cut free from joints, and about six inches long, the famous lamp of Olybius, said to have been discovered in placed upright in a bottle containing some turpentine, soon the year 1500 at Atesta, near Padua. Some peasants digging draws up with its hair-like tubes the combustible fluid, and this the earth to a considerable depth, came to a tomb, in which may be set on fire at the top of the cane, which acts, of course, they found two earthen urns, one within the other. The inner like the wick of a candle. The experiment is hastened by suckvessel is said to have contained a burning lamp, placed between ing up the Avid with the month, or by reversing the cane after two phials, one filled with liquid gold, and the other with liquid one end has been immersed in the turpentine for some minutes. silver. But, unfortunately, the rustics who found this inestim On examining the flame of a candle, it is found to consist of able treasure were not sufficiently careful, and so the lamp three distinct portions. That nearest the wick is almost black, was broken and extinguished. Liceti seems to have confounded the next is very bright and luminous, and the third emits so the myth of a perpetual lamp with the fact that lamps were feeble a light that it is hardly visible. A picture of the flame kept burning night and day in certain temples. There was the of a candle is easily sketched on a wall or on a white sheet of lamp of Demosthenes in the temple of Minerva at Athens, and paper, by placing

it between the wall and a lens condensing a the vestal fires at Rome,

which were not self-supporting, but were sunbeam passed through a hole in the shutter of a darkened religiously watched by the vestal virgins, and supplied with con- room. The shadow of the flame may be seen distinctly, and the

darkest part is actually the brightest, whilst the more distinct The ordinary materials which furnish artificial light during portion of the shadow is that of the outer part emitting the very

tinual aliment.

feeble light. The movement of the air past the flame is also is attached; the smoky flame immediately burns most brilliantly, well shown. The ascending current drags the flame oat to a and if the wick is very thick and the oil good, it will afford a pointed figure, and, whilst rushing past the candle, keeps the considerable amount of light. outside of the cap containing the melted wax or tallow cool. It is a curious fact that when the pressure of the air is reThe air that rushes by so quickly burns up the carbon and duced the luminosity of a burning candle is materially affected. hydrogen of the outer part of the flame, but does not affect so Messrs. Tyndall and Frankland burnt some candles on the materially the next structure, where the hydrogen is chiefly summit of Mont Blanc, and although just as much stearine was burnt and the carbon deposited. Here the flame is the brightest, consumed at that altitude in a given time as at Chamouni, the because of the ignition of the precipitated carbon, and hence aspect of the flames was completely altered. They seemed, to the reason that the shadow of this portion should appear so dark. use their language, to be the mere ghosts of the flames "which In the inner layer the unburned gas is found waiting its turn to the same candles were competent to produce-pale, feeble

, and pass to the exterior, to go through the phases of partial com- suggesting a greatly diminished energy of combustion." bustion and precipitation of the carbon, ending with complete The cause of the diminution of the light is not due to any combustion at the exterior,

reduction of the rate of burning, but to a more perfect diffusive That the interior of a candle flame does consist of unburnt effect; the oxygen of the air penetrates the flame more perfectly, gas may be shown by placing a narrow glass tube in the inner and the matter of the flame passes more rapidly into the air; cone of the flame. The tube must be inclined, and if nicely and thus, by the mutual interpenetration of the one into the managed the hot gas passing upwards may be inflamed at the other, the carbon is more rapidly burnt out. Dr. Frankland also top. The same fact is shown by holding a slip of card across discovered the interesting fact, that by compressing the air the flame. The interior of the cone does not scorch the card, round the flame of alcohol, which burns with a smokeless flame, which is blacked at the two points or opposite sides of the centre. it became as bright as coal gas, and at a higher pressure could

The tube may be adjusted so as to draw away the finely- even be made to smoke. The intensity of any given flame is divided carbon deposited in the luminous portion of the flame, reduced 5 per cent. for every fall of one inch in the barometer, and if this is conducted into a separate small hydrogen flame, the or increased in the same proportion with each rise of one inch. latter becomes luminous in consequence of the incandescence of Dr. Frankland has also shown that the comparative cost of light the carbon derived from the candle. A hydrogen flame affords equal to that obtained from twenty sperm candles, each burning little or no light, but if a small bit of tow, saturated with ten hours at the rate of 120 grains per hour, wonld be as benzole or ether, is placed in the bottle containing the materials follows Wax, 7s. 29d. ; spermaceti

, 6s. Sd. ; tallow, 2s. 8d. ; for generating hydrogen, and the tube or jet fitted into the sperm oil, 1s. 100.; coal gas, 4 d.; cannel gas, 3d. ; paraffin neck of the bottle, on lighting the hydrogen it is now very candles, 3s. 10d. ; paraffin oil, 6d. ; rock oil, 7d. Consequently luminous, in consequence of the carbon, the solid matter de- paraffin and rock oils are the best sources of light for domestic rived from the benzole or ether, being precipitated, ignited, purposes. They are the cheapest, give the greatest amount of and burnt. To distinguish the bright from the almost un- light, and, what is of still greater importance, they do this with luminous part of the flame, the latter is sometimes called the the least developinent of heat. mantle, because it is the outermost cone.

The extraordinary light-giving agents, with the exception of The best method of showing the structure of flame is to the combustion of magnesium in air or of phosphorus in oxygen, place some ether in a tin dish three inches in diameter and require more elaborate apparatus than the beginner in science is half an inch high. On setting fire to the ether a very large likely to be able to afford. The oxy-calcium light is one of the flame is produced, and into its centre may be introduced a cup most simple, and is obtained by forcing a jet of oxygen through containing phosphorus, which only sublimes, but does not burn. the flame of a spirit-lamp, and directing the resulting fire on to a By very careful manipulation, and when the air is still and not ball of lime. This light will do very nicely for the exhibition of disturbed by open doors or windows, gunpowder may be dropped photographs on a small screen in a moderate-sized apartment. down a tube held across the hot stratum, and will fall unburnt If a more brilliant light is required, the lime or oxy-hydrogen into a porcelain or other cup, placed in the centre of the flame. light may be used. It is, of course, easy to place two volumes A very few grains of powder should be used until the operator of hydrogen and one of oxygen in a large bladder furnished has sufficient confidence to perform the experiment steadily. with a stop-cock, and then to burn the mixed gases from a HemThe structure of flame being understood, it is easy to see how ming's jet. This is undoubtedly the cheapest, but not the the illuminating power of an ordinary flame may be increased safest method, especially if the bladder is squeezed by the hands. by admitting the right proportion of air to the interior. The A steady pressure is absolutely necessary, and this can only be argand burner furnishes the best illustration of this well. obtained by using pressure boards. Indeed, it is far better not known principle: if the central tube is corked and the chimney to attempt either the oxy-calcium or the oxy-hydrogen lights removed, the flame is smoky and unsteady; on replacing the without proper caoutchouc bags, pressure boards, and jets, all chimney, the current of air rushes with increased velocity past of which may now be obtained at a very moderate price of the the exterior, and more light is obtained; but the maximum of instrument-makers. The cost of an accident to person or light is only procured when the cork is removed, and air allowed property by the explosion of a large bladder full of the mixed to pass to the interior as well as the exterior of the flame. gases in a dwelling-room is very likely to be greater than the

When the supply of air is too great, the luminosity of the purchase of the proper appliances. argand burner is seriously affected, especially if the gas is not Although the electric light is the most brilliant artificial light rich in hydro-carbons, because the carbon is burnt up at once, that can be procured, it is only effective on a proper scale. A and no time is allowed for its precipitation; hence it is now usual voltaic battery on Grove's principle, of forty cells and a good to adjust the central or internal tube of the argand burner to the electric lamp, will give excellent results, whilst a smaller quality of the gas. The diameter of the internal aperture arrangement is continually flickering, and the constant nové should be less than half an inch-viz., 0.42 of an inch for eleven- ment of the charcoal points become tiresome, and fatigues the candle gas, and half an inch for fifteen-candle gas, if used with eyes of those who may be invited to see the experiments. Here, a glass chimney seven inches long, and burning at the rate of again, a good apparatus is the cheapest in the end. five feet an hour.

The magneto-electric machine will also give a continuous and If coal-gas is mixed with a considerable quantity of air brilliant electric light, but as the armature must revolve many before it is burnt, as in a smokeless burner, or the gauze-burner, hundred times in a minute, and can only be worked effectively the flame is no longer brilliant, because the carbon is burnt

with with the aid of a steam-engine, such a light is a luxury to be the hydrogen.

used only by a rich body such as the Trinity House brethren, When the combustible oil, such as turpentine or camphine, who have employed Professor Holmes' magneto-electric light contains a very largo proportion of carbon, the chimneys are for many years at the North Foreland lighthouse. increased in length, and have a peculiar construction, because The lighted candle in the cottage window has guided many s more air must be supplied to burn the excess of carbon, and to weary husband over fell and moor to his home, but this magneto prevent the fame smoking.

electric light is so large in amount that, with proper optical The Bade light consists of a small argand lamp, burning arrangements

, such as Fresnel's lamp, it will flash its friendly colza oil; and instead of supplying air to the interior tube, a jet, rays twenty-five miles across the ocean, and almost rival conveying oxygen gas from a bledder or small india-rubber bag,

“Those gold candles fix'd in heaven's air."

ELECTRICITY.-III.

the conductor to the knuckle or any other body held to it; or

if bent wires with balls at the end be inserted in the two conCYLINDER ELECTRICAL MACHINE-PLATE MACHINE-ARM

ductors, as shown at D and E, a series of sparks will pass between STRONG'S HYDRO-ELECTRIC MACHINE.

them. It is necessary, if positive electricity is to be used, that It is now time for us to pass on to consider the mode in which the rubber should be connected with the ground, and this is we can obtain electricity in large quantities. This is done by usually done by means of a chain or a piece of wire. In the means of an eleetrical machine, which consists essentially of three same way, if negative electricity is required, the conductor must parts: firstly, the substance to be rubbed, usually a cylinder or be uninsulated. sheet of glass ; secondly, the rubber; and, lastly, the con. As we hope that a great many of our readers will set to work ductor or reservoir to hold the electricity.

and make one of these machines for themselves, we will give Originally a globe of sulphur was employed as the substance rather fuller instructions as to the mode of proceeding. Be to be rubbed, but it was soon discovered that a globe of glass I assured of one thing at starting, and that is that you can easily would answer better, and this

succeed if you only persevere, was accordingly substituted.

B

and are not disheartened by At present, however, a cylin

apparent failure at first. der is usually employed (Fig.

We should recommend you 6). These are made specially

to procure a proper cylinder for the purpose, and can be

if possible; one nine or ten obtained for a moderate

inches long by six or seven amount at glass-works, or

inches in diameter is a very at philosophical instrument

good size, and should not cost makers'. In shape they resem

more than about five shillings; ble a square-shouldered bottle

considerable power may even with a neck at each end. Caps

be obtained from a smaller are turned out of some hard

one. Failing this, a large round

M

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wood to receive these, and should be so shaped that their ends / bottle will answer, but not so well, nor is it nearly so conmay serve as bearings for the cylinder. The winch is fixed to venient. Some people recommend, when a bottle is used, that the squared end of one of the caps.

a hole should be punched through the bottom, but there is conAt one side of the cylinder is placed the rubber, c, which siderable difficulty and risk in doing this. The better plan is to consists of a cushion of wash-leather stuffed with horse-hair or procure a disc of wood a little larger than the bottom of tho tow, and a piece of black silk (not represented in the figure) bottle, and

fix it on by means

of electrical cement. This passes from the under side of this over the cylinder nearly to cement is used for many purposes, and may be easily made. the points on the other side. A conductor, A, is sometimes fired It consists of resin, plaster of Paris, bees’-wax, oil, and red behind the rubber, and serves to collect the negative electricity. lead. The resin is first melted in an earthen pipkin, a small On the other side of the cylinder is the prime conductor, B, lump of bees'-wax and a little oil being added to render it more with a row of points along one side to receive the electricity tough. When fully melted, the

plaster is stirred well in, Holes are bored at different parts of this, in order that brass together with some red lead, to impart a better colour to it. balls and rods or other pieces of apparatus may be inserted The bottle and disc of wood should

then be well warmed, and

the

cement poured upon the former, and if the disc be kept from On turning the cylinder, if the machine has been carefully slipping until it gets cold, the cement will hold firmly. The warmed and dried, and a little amalgam spread upon the larger the proportion of plaster used the harder will be the rubber, vivid sparks, several inches in length, will pass from cement. The winch is put on an axle affixed to this disc, and

92

when required.

VOL. IY

a plug of wood inserted in the mouth of the bottle serves for room, flashes of blue light, accompanied by the peculiar smell a bearing at the other end.

of electricity, and by a faint crackling noise, will be observed When a cylinder is used, caps should be turned of mahogany, passing round the cylinder and issuing from the edge of the or some hard wood, so as to fit loosely on the ends of the cylinder; silk flap. Now bring the conductor so that the points of the these are then fixed on by the cement above referred to, and fork may nearly touch the cylinder, the electricity will then be great care must be taken to ensure the cylinder being mounted collected, and sparks several inches in length may be obtained so as to run perfectly true. If the framework of the machine by holding the knuckle or any conducting substance near it. be made first, it can be put in before the cement is fully set, and If the rubber were insulated, similar sparks might be drawn carefully watched while it is being turned round; it must not, from it, but they would be of negative electricity. The great however, be left in its bearings to set. As the machine is usually point to be remembered in using all electrical apparatus is to warmed before use, an aperture must be left for the escape of have every part of it perfectly dry and free from dust. the air; a hole is therefore drilled through the cap at the ond This form of machine is by far the most common. In it, 19 away from the winch, and, while the cement is being poured we have seen, friction is the exciting cause; hence the power will into the cap, this is filled by a greased wire, which may be be found to depend upon the extent of rubbing surface. With removed as soon as the cement becomes hard,

a view to increase this, two rubbers opposite to one another A better plan of mounting the cylinder has, however, lately have sometimes been affixed to the same machine, and two conbeen tried. The inside is first rendered perfectly clean, and ductors placed between them ; this, however, adds so greatly to then thoroughly dried by exhausting the air, and allowing a fresh the complication of the machine, that the plan is nearly dissupply to enter through a drying tube. When it is thus pre-carded. pared, the caps are put on so as hermetically to seal it. The sur If we remove the chain or wire connecting the rubber with face of the cylinder is rubbed before nse with a rag wetted with the ground, and place one so as to make a communication turpentine, so as to remove all grease, lumps of amalgam, etc., and between the rubber and conductor, we shall find that no spark it is then polished with prepared chalk. This imparts a greatly can be obtained from either, showing that the quantities of increased power to the machine, for sparks of a much greater positive and negative electricity are exactly equal, and therefore length can be in this way obtained, and there is little need of neutralise each other. warming the cylinder before use. Another advantage is that Though the cylinder machine is that most generally used, its the damp does not condense so readily upon it, and thus place is sometimes taken by the plate machine (Fig. 7), especially it can be used at a lecture-table or in a room filled with when great size and power are required. By some this form is prepeople.

ferred as being more compact and ornamental, and the power is The frame-work of the machine can easily be made. It should usually supposed to be about equal for an equal rubbing sur be formed of thoroughly dry wood, baked for a little time; and face; but when the cylinder is mounted on the plan mentioned in making it, great care must be taken to avoid all points and above, the advantage in point of power is on its side. sharp edges which draw off much of the electricity. The support A plate of thick glass has its edges carefully smoothed and at the winch end should be made with a cap, so that the cylinder a hole drilled through its centre for the axle to pass through. may be removed when necessary, and the under side of the This is made of brass, with flanges to press against each side cylinder should be five or six inches above the board.

of the plate and hold it firmly; but as brass is a conductor of It is simpler, too, to make the rubber in a way rather different electricity, a part of the winch is usually made of glass, to from that shown in the figure. As it is not often required to prevent the electricity being conducted away. Two rubbers, obtain negative electricity, the support may be of baked wood, F, F, are employed in the machine, and they are made double, so and the whole should then be shaped like the letter T, the as to grip the plate between them, and thus cause friction on lower end being hinged to the edge of the board, and a hole each side of it." Quadrants of silk are also affixed to the rabber made about two inches up, through which a thumb-screw may to prevent the escape of the electricity before it reaches the pass into a wooden block placed a little way from it, so that conductor, just as a flap of silk was used for the same purpose by means of the screw the rubber may be pressed firmly against in the cylinder machine, and the power will be much augmented the cylinder. Care should be taken in the construction of the if this be covered with varnish. The main disadvantage in this rubber, as much of the power of the machine depends upon it. machine is the difficulty of insulating the rubber so as to draw It should be about one and a half inches wide, and rather negative electricity from it. shorter than the cylinder. Wash-leather answers well for its The conductor is sometimes made in two pieces, as shown at covering, and the horse-hair or tow in it should be so arranged C, c, and the further ends are then connected by a brass rod, but as to give a uniform pressure. The silk flap is fixed to the more frequently it is semicircular, and supported by a single glass under side, and passes up in front of the rubber. At the back upright. The fork should be bent round so as to collect the is a small hook, to which a piece of chain may be attached, and electricity from both sides of the plate, instead of from one only, a wire should come from this to the under part of the rubber, as is frequently the case. Great care is required in warming and there be connected with a piece of tin-foil running the this machine, lest the plate should become unequally hented and whole length of it. This is often omitted, but as the materials, crack. The best plan is to lay some silk handkerchiefs over of the rubber are not good conductors, this simple addition it, and let it stand a little way from the fire. greatly increases the power. The chain from the hook should Ebonite or vulcanite is now sometimes used in place of glass be allowed to touch the ground, or, better still, be connected for the plate, and possesses many advantages over it. A larger with a gas pipe, as thus a plentiful supply of electricity will be amount of electricity may be obtained from it, and it is not obtained from the earth, which is the great reservoir of it. The liable to crack as a glass plate is, nor does the damp condense conductor of the machine may be made as shown in Fig. 6, on it so readily. Still, it is much softer, and therefore will but is rather more convenient, if mounted on a separate stand not wear quite so long. For an ebonite plate, hareskin is one The points, too, instead of being placed along the side, may be of the best materials for use in the construction of the rubber

. fixed on a separate piece fitting into one end of the conductor. It must be thoroughly cleansed from grease, and the amalgami A very good fork may be made by rounding the ends of a piece used must be softer than that used with glass. of wood about the size of a small ruler, covering it with tin Plate machines have occasionally been constructed with two foil, and inserting a row of needles along one side. The prime or more plates fixed parallel to one another on the same axis

. conductor, also, may be made of wood covered with tin-foil, A much greater increase of power is, however, obtained by the and should have its end somewhat bulging, as shown in the use of a very large plate. At the London Polytechnic there is engraving.

one with a plate about seven feet in diameter, and driven by a When the machine is wanted for use, every part should be care- small steam-engine, from which sparks of great length and fully

rubbed dry and clean with warm cloths. The rubber screw power may be obtained ; and even this size has been exceeded, should be loosened, and the rubber turned back, so as to allow for some time ago there was one at the Panopticon with a tenof the old amalgam being scraped off, and a fresh supply placed feet plate. Machines of this size require, of course, great care on the cashion under the silk flap. It may then be replaced in their use, as a spark from one of them would be nearly sufand pressed firmly against the cylinder by means of the screw, ficient to knock a man down, and injurious effects might posor by the pressure of the hand on it.

sibly be produced Now turn the cylinder, and if the machine be in a darkened Several other machines for producing electricity, or modified

tions of the preceding, have been tried with varying degrees was learned and studied from him alone. He threw all his of success, but scarcely any of them are enough used to call for predecessors into the shade, and nearly all subsequent historians our attention here. The only one we shall refer to is that confined themselves to abridging his work." known as Armstrong's hydro-electric machine (Fig. 8). Some According to the early legends, the original inhabitants of years ago it was noticed that when steam was issuing rapidly from Rome were almost entirely men, and being mostly criminals and a boiler, sparks were at times given off from it. Sir William runaway slaves, they found it impossible to obtain any of the Armstrong investigated the phenomenon, and was thus led to women of the neighbouring states in marriage. In this difficulty, devise the machine we are now about to explain.

Romulus, the king and founder of the city, had recourse to an The body of it consists of an ordinary steam-boiler, complete artifice. He invited the Sabines to a festival at Rome, and they with furnace, tubes, etc. A water-gauge, to show the level of came without suspicion, bringing their wives and daughters; the water, is seen at the side, and a safety-valve is fitted to but in the midst of the festivities the Romans rushed on them it above. When the steam has acquired sufficient pressure, the with drawn swords, and carried off a great number of the women tap, c, is turned on, and the steam then escapes through the (the rape of the Sabines). War ensued, and a battle was fought jets at A. These jets are formed of box-wood, as shown in which seemed likely to have ended in the total destruction of section at M, so that the steam is not allowed to escape in an the Sabine army. At this crisis our first extract comes in :uninterrupted way, but is caused, by means of a bent piece of

LIVY, I. 13. metal, to strike against the sides of the mouth-piece. The box, B, is filled with cold water, which partially condenses the steam

Tum Sabinæ mulieres, quarum ex injurial bellum ortum erat, before it issues. When the steam is allowed to issue in this crinibus passis, scissaque veste, victo malis muliebri pavore, way from the jets, it will be found to be highly charged with ausæ se inter tela volantia inferre, ex transverso impetu facto positive electricity, which may be collected by a number of dirimere infestas acies, dirimere iras, hinc patres, hinc virogt points or a bundle of wires, P, supported on an insulating stand orantes, ne sanguine se nefando soceri generique respergerent, and connected with a prime conductor, D.

ne parricidio macularent partus suos, nepotum illi, hi liberum The boiler itself is supported on stout glass legs, and be progeniem. “Si affinitatis inter vos, si connubii piget, in nos comes very highly charged with negative electricity--so much vertite iras: nos causa belli, nos vulnerum ac cædium viris ac so that sparks nearly two feet in length have been obtained parentibus sumus, melius' peribimus quam sine alteris vestrum from a machine of this kind.

viduæ aut orbæ vivemus." Movet res quum multitudinem, tumo If acid or a salt be added to the water in the boiler, all duces ; silentium et repentina fit quies : inde ad fædus faciendum evolution of electricity will cease; if oil be added, the boiler duces prodeunt, nec pacem modo sed civitatem unam ex duabus will become positively charged, and the steam negatively.

faciunt, regnum consociant, imperium omne conferunt Romam.10 In this machine, as in the others we have considered, the Ita geminata urbe ut Sabinis tamen aliquid daretur, Quirites a real cause of the electricity is friction. The steam becomes

Curibus appellati. partially condensed, and therefore contains a number of minute

NOTES. globules of water. These, being carried along with the steam, 1. Quarum ex injuria. The genitive of the object : from the injury strike violently against the tongue, and, by their friction done to whom. against it and the sides, evolve the electricity. If perfectly

2. Victo, abl. absolute, agreeing with pavore: the fear natural to their dry steam be used, or if the jets allow a free passage, no elec. sex being overcome by the horrors of the scene.

3. Impetu facto, rushing across, between the combatants. tricity will be produced.

4. Patres-viros, their fathers, who were Sabines; their husbands, the Romans, who had forcibly married them.

5. Ne sanguine, etc., not to stain themselves with impious blood; these READINGS IN LATIN.-V.

of their fathers-in-law, the others of their sons-in-law.

6. Nepotum-liberum, grandsons to their fathers, the Sabines ; sons LIVY.

to their husbands, the Romans. TITUS LIVIUS, the greatest of the Roman historians, was born 7. Si affinitatis, “If," they say. The construction changes from the at Patavium, the modern Padua, about 60 B.C., and died in the oratio obliqua to the oratio recta, in which the actual words of the year 20 A.D. From the name of his birthplace he is called speakers are reported.

8. Melius, it will be better for us to die. Patavinus, and the occasional provincial expressions which some

9. Qaum-tum, first one, then the other, and so both, and. writies have affected to detect in his style have been called, from 10. Conferunt Romam, lit., they bring together to Rome; they con the same cause, Patavinitas. He is said, in his earlier years, to centrate at Rome. Romam, accusative of motion to a place. nave published some works on rhetoric, but the recollection of hese has been eclipsed by the magnificence and colossal pro- that is no doubt well known to most of our readers, the defence of

Our second extract is part of the account of a deed of bravery ortions of his history of Rome from the earliest period down to the bridge by Horatius Cocles, which forms the subject of the best is own days. Of this work comparatively a small portion has of Macaulay's “ Lays of Ancient Rome." The last of the kings bached us. It is believed that he intended completing it in 150 of Rome, Tarquinius Superbus, who had been driven from the ooks, divided into fifteen decads or sets of ten books each, and state for his great cruelties, made

several vigorous efforts to reE these he wrote 142. All that are extant in their entirety are gain the crown he had lost. He summoned to his aid Porsenna, he first, third, and fourth decads--in other words, Books I.-X. lord of the neighbouring state of Clusium, who came with a nd XX.-XL. The only other remains are abstracts of the conents of all the 142 books, with the exception of Books CXXXVI. strong army to attack Rome. The only hope for the Romans ad CXXXVII., and a few isolated fragments. Though con- lay in breaking down the bridge over the Tiber, and so preventLining occasional obscurities, the style of Livy's writing is, as

ing the entrance of Porsenna's army, but the enemy were close

upon them before they accomplished their object. In this whole, remarkably pure and elegant, and his descriptions are ways forcible and picturesque. As a statement of facts his juncture a brave Roman, named Horatius, volunteered to keep scount of the early period of Roman history is not to be the passage of the bridge, with two of his friends, until the pended upon, though for a long time it was accepted as true;

Romans should be able to cut it down :id it was reserved for Niebuhr, one of the greatest of German

LIVY, II, 10, 5. holars, to show that Livy had, in the absence of more reliable Vadit inde (Horatius) in primum aditum pontis, insignisque thorities, merely taken for granted and repeated the stories of inter conspecta cedentium pugnæ terga obversis comminus ad e old annalists, which were in point of fact little better than ineundum prælium armis ipso miraculo audaciæ obstupefecit bulous, without taking the trouble to examine them critically; hostes. Duos tamen cum eo pudor tenuit Sp. Lartium ac T. t as the work proceeds it increases in historical value. Herminium ambos claros genere factisque. Cum his primam shuhr says of him, "Few authors have exercised an influ- periculi procellam, et quod tumultuosissimum pugnæ erat, cP like that of Livy; he forms an era in Roman literature; parumper sustinuit: deinde eos quoque ipsos exigua parte d after him, no attempt was made to write Roman annals. pontis relicta, revocantibus: qui rescindebant, cedere in tutum s tepatation was extraordinary. It is well known that one coegit. Circumferens inde truces minaciter oculos ad proceres in came from Cadiz to Rome merely to see Livy; and this re- Etruscorum, nunc singulos provocare, nunc increpares omnes, tation was not ephemeral; it lasted and became firmly esta servitiam regum superborum suæ libertatisă immemores, alienam shed. Livy was regarded as the historian, and Roman history oppugnatum venire. Cunctati aliquamdiu sunt, dum alius aliv

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