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gli-fo

Italian.
Pronounced.
English.

ANSWERS TO CORRESPONDENTS.
Quojo
kwô-yo
Leather, skin

CIVIS (Dublin): We recommend him to take up Part I. of the French

Lessons from the P, E, to follow the Lessons from the W. M.F.. Part II. Seguace sai-gwah-tchai Follower, disciple of the former will be ready in about three weeks.-AMBITION (Copthall Insegue in-sê-gwai

He pursues

court) will see the studies that it will be necessary for him to take up Inguine in-gwee-nai

Groin

If he wishes to matriculate at the University of London, in vol. ii. of the

P. E., p. 137. Liguori lee-gwô-ree

Liguori Aquario ah-kwah-reco

Aquarius

EIPSELLIG (Leicester): Right.-CARMONEY (Belfast) will see by the solu.

tion we have inserted that his is wrong. Thanks for his other communicaLoquela lo-kwê-lah

Tongue, language

tions.-SPEUDE BRADEOS (Fetter-lane): His conjecture about the Greek Aquila áh-qwee-lah

Eagle

extract is right; but that about the Greek lesson is wrong. There is a very Aquoso

considerable difference between the ancient and the modern Greek. We be. ah-qwó-80 Aqueous, watery

lieve that old Homer would not be understood in his own country.-J. MILLS Lingua lín-gwah

Tongue, language

(Tewkesbury): His poetry is good, but not sufficiently measured ; that is, Sangue sáhn-gwai Blood

put into the proper number of syllables in each line; some lines bave ten Pingui pín-gwee Fat, plump

syllables, some twelve, and so on. Were we to correct it, we would begin Pasqua

thus :
páh-skwah

Easter
Cinque
tchín-kwai
Five

" Ah, dost thou gaze upon that little child,

And smile with admiration at its form?
Iniquo
ee-nee-kwo
Unjust, iniquitous

Scarcely as yet unfolded, helpless thing,
Adequi
ah-de-kwee
Thou comparest

What is there in its features so divine,
Or in its wondrous structure so profound ?

This is but one of Nature's lovely works, 6. Cla, Cle, Cli, Clo, Clu, Gla, Gle, Gli, Glo, Glu.

With which earth teems throughout her wide domain.
Behold the smallest insects far surpass,
In texture delicate, this blooming child !

Their microscopic organs how minute,
Italian.
Pronounced.
English.

Their mechanique, how wonderfully fine!

But ah, within that infant form there lies
Clava
klah-vah
Club

A soul divine; a young immortal soul!
Clero
klê-ro
Clergy

A soul of worth so infinitely great,
Clima
kleé-mah
Climate

That all the powers of Mathematic lore

Its value cannot calculate or weigh."
Cloto
kl8-to

Clotho, one of the Fates
Clusio
kloó-zeeo
Clusium, a town

A. RICHARDSON (Newcastle) and E. EVANS (Ashby-de-la-Zouch): We

regret that we cannot give them the information they require.-W. X. Gladio gláh-deeo*

Knife, poniard (Manchester) and PARALLAX: We advise them to write to Messrs. Watkins Gleba glê-bah Clod of earth

and Hill, 5, Charing-cross, London, who will furnish them with a catalogue Grifo

Glyph (in architecture) of their telescopes, achromatic and reflecting, with their sizes, powers, Globo

and prices. They can also have information from the same firm about magic glo-bo Globe

lanterns, sliders, and diagrams or atlases of the heavens. Gluma glob-mah Chaff

C. B. C. (Hull) must study our Lessons in Penmanship, vol. ii., P. E.Reclamo rai-klah-mo Reclamation

T. MUXLOW (Sheffield): Get an old copy of Barrow's Euclid (which you may at any old book-stall for 18.), and you will see all the books of Euclid from the Ist to the 15th inclusive.-W.HADFIELD (Hayfield): We know of no paper in which excise vacancies are advertised.-W, J. OSBORNE (Soho); We

think that the courtesy is due to any clergyman who does not wish his This is the first occurrence in these lessons of the important sermon taken down in short-hand, to refrain from so doing; he is the best combination gl. It has two different sounds. When it is not fol- judge of the value of his own productions.-J. ADDER (Grandtully): The lowed by the letter i it has the sound of gl in gland, glebe, glory, rule for finding the index of the quotient is this: Subtract the index of the

dividend from that of the divisor, and the remainder is the index of the glue ; and this sound can offer no difficulty. But when the com

quotient; now this being done for the first term in every step of the opera. bination gl is followed by the letter i and one of the vowels a, e, o,

tion for finding the greatest common measure, there can be no difficulty at and u, it is pronounced precisely as the double ? (ll) in the French the end, for the remainder will take the indices of its terms from those words bouilli , fille, gresiller, grenouille, bouillon, billard, billet, brouillon, which

correspond to them in the dividend, supposing them, of course, to be feuillu, and, generally speaking, in all those words where the ll has in arithmetical progression proceeding from that of the first term. after the vowel i a squeezed sound in the French language. They T. TAIT (Glasgow) should attend to the directions given in No.36, vol; who are unacquainted with French may form a notion of this ii.-N. P. P. should apply to the superintendent of the docks where he sound by separating and inverting the gl in the enunciation, i.e., by wishes to be admitted.-W. R. E. (Gray's-inn-road) and A SUBSCRIBER pronouncing I before the g, and changing the latter into y. Only are informed that Mr. Cassell has published the very book they want, “ The the first I must go to one syllable, and the second I along with the People’s Biographical Dictionary,” compiled by Dr. Beard, and that it may

be had at this office for 25. 4d. in paper covers. The Atlas is progressing in y, and with a squeezed sound to the beginning of the next, while the P. E. Lord Byron swam the Hellespont. Don't bind the Magazine of care must be taken that the voice should glide rapidly from one Art," or any other periodical, too soon; sell your copy and buy another, syllable to the other, by which means a more equal distribution of taking more care next time.-J. Bewley (Langrigg) : His verses are very the squeezed sound Uy will be produced, and a correct pronunciation good, but not up to our mark.-A TROUBLESOMB SUBSCRIBER will find an

", Latin wards," col. 2, p. 288, vol. il. of the gl effected. An approximation to this sound may be found article on shell-cleaning in the P.E. in the English words million, miliary, biliary, billiards, seraglio, in- should be " Latin words” certainly:-STUDENT OP ANGLBSBA: In the pas

sage si cupis placere magistro," the "si" means only is: “cupis" means taglio, and oglio. The letter i, between the combination gl and the you desire, as shown by the termination " is; ".... placere," to please, accordvowels a, e, o, and u, is (as well as in the combinations cia, cio, ciu, i ing to the Latin idiom, requires the dative "magistro," to the master, to and gia, go, giu) a mere auxiliary letter, i.e., a mere soundless, follow it; but we cannot literally say in English, to please to the master; written sign, to indicate that.gl before a, e, o, and « is not to have yet, as to please means to give pleasure, we can say to give pleasure to the the sound of gl in gland, glebe, glory, and glue, but that squeezed the body; but the neglect of washing the body, which is a great sin,

master. Death would be the consequence of the stopping up the pores of sound, the imitation and description of which I have here besides being a great evil, is compensated for, in strong and healthy persons, attempted.

by copious and heavy perspiration, which literally washes the body itsell, For example : caglio (váhl-lyo), a sieve ; meglio (mêl-lyo), better; be long continued with impunity.-CHEMICUS (Falkirk): Mr. Cassell is

and clears the pores for a time. Still this is an unhealthy state, and cannot piglio (píl-lyo), I take, seize; misouglio (mis-kool-lyo), mixture; about to publish a work on Botany. svegliare (zvel-lyáh-rai), to awake; togliere (tôl-lyai-rai), to take away; scegliere (shél-lyai-rai), to choose ; doglia (dol·lyah), sorrows; bigliardo (žil-lyáhrr-do), billiards; biglietto (bil-lyét-to), note, bill; imbroglione (im-brol-lyó-nai), a meddling fellow; fogliuto (fol-lyoó

LITERARY NOTICES. to), full of ieaves. Egli, he, eglino, they, quegli, that one, gli (the

GERMAN. plural of the article or the prono with its numerous composi.

CASSELL'S GERMAN PRONOUNCING DICTIONARY, in Numbers, 3d. eacn, tions, and gli, the final inflexion or terminational syllable of nouns

or Parts, 1s. each. The entire work will be issued at 8s. 6d. in strong and verbs, have always the squeezed sound Uyee; while the mere binding. spllablegli, at the commencement and in the middle of words, always CASSELL'S LESSONS IN GERMAN. Part I., price, 28: in paper covers, or has the sound of gl in gland, glede, &c. The only exception is 28. 6d. neat cloth. Part II. will shortly appear. Angli, Englishmen, pronounced áhn-glee. For example: figli Cassell's LESSONS IN GERMAN PRONUNCIATION. Price 1s. 6d. in paper (1-lyee), sons; fogli (fôl-Iyee), leaves of paper; gigli (jíl-lgee), covers, or 23. neat cloth, will shortly be issued.

CASELL'S ECLECTIC GERMAN READER, price 2s. in paper covers, or lilies : nogligerc (nai-gleé-jai-rai), to neglect; negligente (nai- 29.6d. neat cloth. glee-jén-te), negligent; negligenza (nai-glee-jên-isab), negligence; CASSELL'S ELEMENTS OF ARITHMETIC (uniform with Cassell's EUOLID) segligentare (nai-glee-jer-táh-rai), to neglect.

is now ready, price Is. In stiff covers, or lø. 6d, neat cloth.-KEY, 3d,

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ON PHYSICS OR NATURAL PHILOSOPHY

This plate is furnished with a funnel-pipe at R, by which tae

water is admitted into the cylinder, and with an air-tight No. VIII.

pump-body and piston, the latter being moved up or down by

means of a screw P. In the interior of the apparatus is conHYDROSTATICS.

tained a glass reservoir A, filled with the liquid whose comThe Science of Liquids at Rest.—Hydrostatics is that part of pressibility is to be ascertained. This reservoir terminates in natural philosophy which has for its object the investigation

a bent capillary tube, the lower end of which is immersed in a of the conditions of equilibrium in liquids, and of the pressures

mercurial bath at o. This tube is previously divided into which they produce, either in mass, or on the sides of the parts of equal capacity, it having been ascertained how many vessels which contain them. The science which treats of the of these parts the reservoir a contains ; this is found by determotion of liquids is called Hydrodynamics ; and the application mining the weight p of the mercury contained in the reserof its principles to the art of conveying and raising water is voir A, and the weight p of the mercury contained in a certain particularly denominated Hydraulics.

number n of the divisions of the capillary tube; then, denotGeneral Character of Liquids.—It has been already stated the reservoir by x, we have the following proportion p: P ::

ing the number of the divisions of the small tube contained in that liquids are bodies of which the particles, in consequencen: N; whence, the value of N can be easily deduced. of their extreme mobility, yield to the slightest effort made to displace them. Their fluidity, however, is not perfect ; for

In the interior of the cylinder is contained a Manometer among their particles there always exists an adherence which (rarity measurer) of compressed air. This is a glass tube B, constitutes a greater or less degree of viscosity (stickiness).

closed at the upper extremity, and open at the lower extrethe gases ; the distinction between liquids and gases being, the tube B is completely full of air; but when pressure is The fluidity of liquids is manifest, but in a higher degree, in mity, which is also immersed in the mercurial bath o. When

no pressure is applied to the water which fills the cylinder, that the former possess the property of compressibility in a very slight degree, whereas the latter are highly compressible and applied to the water in the cylinder, by means of the screw P elastic.

and the piston to which it is attached, this pressure is comThe fluidity of liquids is shown by the facility with which compressing the air contained in it. A graduated scale ,

municated to the mercury, which then rises in the tube s by they take all kinds of shapes ; their small compressibility is placed alongside of the tube, indicates the quantity by which proved by the following experiment.

the volume of air is diminished; it is by means of the quantity Compressibility of Liquids.—Subsequently to the experiment of diminution in the volume of air that the pressure on the of the academicians of Florence formerly mentioned, liquids liquid contained in the cylinder is determined, as will be were for a long time considered to be incompressible. After- afterwards shown. wards, experiments were made on this subject, in England by Canton in 1761, and by Perkins in 1819; at Copenhagen, by is first filled with the liquid whose compressibility is to be

In making experiments with this apparatus, the reservoir a Ersted in 1823, and again by Colladon and Sturm in 1827. found ; the cylinder is then filled with water by means of From these various experiments, it has been concluded as a the funnel-pipe R. The screw P is then turned so as to make fact that liquids are really compressible.

the piston descend and produce a pressure on the water and The apparatus empioyed in measuring the compressibility of the mercury contained in the cylinder ; this pressure not only liquids are called Piesometers, that is (from the Greek), Pres. raises the inercury in the tube B, but also in the capillary tube sure-measurers. The following is a description of that of (Ersted, fastened to the reservoir A, as shown in the figure. The rise with the improvements of M. Despretz. This piesometer, fig. of the mercury in the capillary tube shows that the liquid con19, is composed of a very strong glass cylinder, about 3} inches tained in the reservoir has diminished in volume the measure

of its diminution being indicated on the tube itself, as above Eig. 19.

mentioned.

In his experiments, Ersted supposed the the capacity of the reservoir remained invariable, and that the sides of it were equally acted upon by the liquid both in the interior and on the exterior, Mathematical investigation has proved that this capacity is diminished by both pressures. In their experi. ments, Colladon and Sturm took this change of capacity into account; and they have proved that for a pressure equal to that of the atmosphere, and at the temperature of 32° Fahrenheit, the parts of the original volume by which certain liquids were contracted, are as follows:Mercury ......

.-000005=utooo Distilled water.

•000049=es Ditto, freed from air

.-000054=18118 Sulphuric ether.....

................ ... .000133=75 They also observed that in the case of water and mercury, within certain limits, the diminution of volume is proportional to the pressure.

Principle of Equality of Pressure.–On the supposition that liquids are incompressible and possess perfect fluidity, and are freed from the action of gravity, the following principle, called the principle of equality of pressure in every direction, universally holds good : liquids communicate in all directions, with the same intensity, the pressures applied to any point of their mass. This principle was first announced to the world by the celebrated Pascal, who died in 1662, and is sometimes called the principle of Pascal.

In order to have a proper idea of this principle, suppose a vessel, fig. 20, of any shape whatever, to be filled with water,

aud that in its sides at different places cylindrical openings in diameter. This cylinder, which is completely filled with A, B, C, D, and e are made, to which there are applied moveable water, is terminated at the bottom by a wooden stand, in which pistons exactly fitting them. If to any, piston a, an external it is firmly cemented; and at the top a copper cylinder is fixed pressure be applied, say of 20 pounds this pressure is instit to it, by means of a plate, which can be unscrewed at pleasure. I taneously communicated to the internal surfaces of the pistons

VOL. IV.

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86

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Fig. 21.

3, 5, D and e, and they will be pushed outwardly with a pres- the direction mp, may be decomposed into two forces, the one more of 20 pounds, if their surfaces be each equal to that of the e, acting in the direction me perpendicular to the sarface A B,

and the other F, acting in the direction mp or BA. The first Fig. 20.

force e will be counteracted by the resistance of the liquid mass, and the second i will urge the particle m in the direction

The same reasoning being applicable to every particle of the liquid surface, it is evident that this surface cannot remain at rest in the direction B a inclined to the horizon, but must assume the horizontal direction, when the force acting in the direction B A becomes zero.

If the liquid be acted upon by other forces besides that of gravity, its surface will tend to take a direction perpendicular to that of the resultant of all these forces, as will be seen in the case of the phenomena of capillary attraction. According to the principle explained above, when a liquid is contained in a vessel or basin of small extent, its free surface is plane and horizontal, seeing that at every point of that surface the direc

tion of gravity is then the same. This is not the case, how. piston A; but if their surfaces be (wice, thrice, or four times ever, in the surface of a liquid of great extent, such as that of ihat of the piston A, the pressure communicated will be 40, 60, the sea. For the surface of the sea being everywhere perpenor 80 pounds accordingly; that is, the pressure communicated dicular to the direction of gravity, and this direction varying increases proportionally to the surface.

in different places considerably apart from each other, it is The principle of equality of pressure is generally considered plain that the surface of the sea changes its direction with as a consequence of the constitution of liquids. It can be that of gravity; and the latter being constantly directed to proved by the following experiment that the pressure is the centre of the earth, the former causes the sea sensibly to really communicated in all directions; but it does not prove assume a spherical form, as may be observed in the phenomena that it is equally so. A cylinder, fig. 21, in which a piston of a ship approaching to, or receding from, the shore.

PRESSURE IN LIQUIDS RESULTING FROM THE

ACTION OF GRAVITY. Laws of Vertical Pressure Downwards.- If we suppose a liquid to be in a state of rest in a vessel, and imagine it to be divided into horizontal layers of equal thickness, it is plain that each of these supports the weight of all the layers which are above it. Throughout the liquid mass, therefore, we see that gravity gives rise to pressures which vary from layer to layer, and from point to point. These pressures, which come under our consideration in their effects on the bottom and sides of vessels, are subject to the following general laws:-

let. The pressure on every layer is proportional to its depth.

2nd. The pressure is the same on all points of the same horizontal layer.

3rd. At the same depth, in different liquids, the pressure is proportional to the density of the liquid.

4th. In the same liquid, the pressure on any layer is independent of the form of the vessel, and only depends on the depth of that layer.

Three of these laws may be considered as self-evident; the

proof of the fourth will be seen when we come to the con. moves, is fixed to a hollow globe on which are placed a num-sideration of the pressure on the bottom of vessels. ber of small cylindric pipes, all perpendicular to the surface. Vertical Pressure Upwards.—The downward pressure of the The globe and the cylinder being filled with water, if the pis. upper layers of a liquid upon those which are below them, ton be pushed inwards the water will spout through all the produces in the latter a reaction which is equal and contrary, orifices or pipes, and not through that only which is opposite in consequence of the principle of the communication of to the piston. The reason why the principle of equality of pressure in all directions. This upward pressure is denomipressure, or, as it has been elegantly termed, the Quaquaversal nated the resistance of liquids. It is very sensible when we Pressure, cannot be perfectly proved, is that in our experiments push our hand into a liquid, especially if it be one of great we cannot take away weight from the liquids, nor friction from density, such as mercury. the pistons which communicate pressure to them.

Direction of the Surface of Liquide.- When a liquid is acted on by the force of gravity only, its surface always tends to take a direction perpendicular to the direction of that force. Chus, suppose that the surface of a liquid, as water, takes for an instant the direction B a, fig. 22, inclined to the horizon, the

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Fig. 23.

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To prove this fact by experiment, we employ a glass tube the quantity of liquid which it contains As to the bottom open at both ends, fig. 23. "To the lower end of this tube is of the vessel, it is evidently the same in the two cases, that is, applied a disk of glass B, which serves as a stopper, and which the surface of the mercury in the tube A C. is supported in its position by means of a thread a which is

From this law, it is evident that by means of a very small fastened to it. This apparatus being immersed in a glass quantity of water very considerable pressures may be obtained, vessel nearly full of water, the hand is removed from the For this purpose, we have only to fix in the side of a closed thread and ihe disk is left free. This disk then remains as a vessel full of water a tube of very small diameter and of great stopper applied to the tube, indicating that it is supported by height; this tube being filled with water, the pressure comthe upward pressure of the water, which is greater than the municated to the side of the vessel is equal to the weight of downward pressure of its weight. Now, if water be slowly the column of water which has this side for its base, and whose poured into the tube, the disk will continue to support this height is equal to the height of the tube, 'Thus the pressure water until the level of the water within the tube is nearly of the water on the side of the vessel may be indefinitely the same as that without, when the disk will fall to the boto increased. In this manner, a narrow pipe of water of the tom of the vessel. This experiment proves that the downward (height of 33 feet has burst a strong and well-constructed pressure on the disk is equal to a column of water having for cask. its base the interior section of the tube, and for its height the distance of the disk from the upper surface of the water in exists at the bottom of the sea may be determined. It is

On the principle just proved, the pressure of water which which the tube is immersed. Hence, the resistance or upward known, and will soon be proved, that the pressure of the pressure of liquids, as well as their downward pressure, is atmosphere is equivalent to that of a column of water of 33 proportional to their depth.

feet. Now navigators have often observed that the sounding Pressure on the Bottom of Vessels. The pressure of a liquid lead does not reach the bottom of the sea at a depth of about on the bottom of the vessel which contains it, is regulated by 13,200 feet. There is therefore a pressure equal to 400 times the same laws as the pressure on any layer of that liquid; that of the atmosphere at the bottom of a sea of the depth of that is, it depends only on the density of the liquid and on its 24 miles. depth, and not on the form of the vessel. That the pressure Lateral Pressure of Liquids. The pressure which arises from on the bottom of vessels is independent of their form is proved gravity in the mass of a liquid is communicated in all directions by the following experiment, the apparatus for which was according to the quaquaversal principle; hence, it follows invented by M. de Hâldat.

that the pressures which take place perpendicularly to the This apparatus is composed of a bent tube a cd, fig. 24, on vertical sides of vessels are included in the laws of vertica!

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which, at a, two vessels m and Ý can be screwed in succession, pressure. It has been proved both by analysis and by experiof the same depth, but of different form and capacity, the first ment, that the pressure on a given side of a vessel is equal to being conical and the second cylindrical. The experiment is the weight of a column of water which has that side for its made by pouring mercury into the tube ac, until its level base, and for its height the vertical distance of its centre of nearly reaches the cock Á. The vessel s is then screwed on gravity from the surface of the water. As to the point of the tube and filled with water; the water by its weight forces application of this pressure, it is always a little below the the mercury back and causes it to rise in the tube at c 1, and centre of gravity. This point is in fact called the centre of its level is marked by means of a slide , which moves along pressure ; and its position is determined by calculations of the part of the tubé o D. The level of the water in the which the following are some results : 1st. The centre of pres vessel is marked by means of a moveable rod placed sure of a rectangular side, of which the upper edge is level adove it. These levels being noted, the vessel m is emptied by with the water, is situated downwards from that edge at twothe cock at A; it is then unscrewed, and replaced by the vessel thirds of the straight line which joins the middle of its horiP. Now, on pouring water into this vessel, the mercury which żontal edges. 2nd. The centre of pressure of a triangular side had resumed its original level in the tube at a, is again raised of which ihe base is level with the upper surface of the water, in the tube at c; and as soon as the water reaches the same is in the middle of the straight line which joins the vertex of level in the vessel P, which it had in the vessel m (which is the triangle with the middle of the base. 3rd. The centre of preserved by the position of the rod above it), the mercury pressure of a triangle whose vertex is at the level of the water, takes exactly the same level in the tube at it, as it did before, and base horizontal, is at the distanre of three-fourths of the this being indicated by the slide #. This pressure is therefore straight line joining the vertex and the middle of the base independent of the shape of the vessel, and consequently or from that vertex.

The Hydraulic Tourniquet.- When a liquid is in equilibrium principle of Pascal, the upward pressure of the liquid column, in a vessel, it produces on the opposite sides along each hori. whose section is H BPG, on the annular side of which PGPR is tontal layer pressures equal and contrary in pairs, which a section, is equal to the weight of a column of water which counteract each other, so that the existence of these pressures would fill the space of which o PG HEF R 1 is a section. The is not manifest ; they are, how ever, proved by the Hydraulic effective pressure of the liquid on the body supporting the Tourniquet. This apparatus is composed of a glass vessel, fig. 25, which, resting on a pivot, revolves freely round a vertica!

Fig. 26.

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Fig. 25,

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base, is therefore the weight of the volume de water which fills the space whose section is OMNI, diminished by that of the water which would be contained in the space whose section is OPGUE FR I, that is, in fact, the weight of water actually con. tained in the given vessel.

If the vessel has the same diameter throughout, the water presses with the same force both on the bottom and on the supporting body; if the vessel has a greater diameter at the top than at the bottom, the pressure on the bottom is less than

on the supporting body. axis. On this vessel, at its lower end, is fixed, perpendicular to its axis, a copper tube bent horizontally at its two ends and in opposite directions, the bottom of the vessel being fixed in the middle of the tube. If the apparatus be filled with water, LESSONS IN BOOKKEEPING.-No. VII. and the tube quite closed at both ends, the interior pressures on the sides of the tube counteract each other, and no motion

HOME TRADE. ensues. But if the tube be open at both ends, the liquid

(Continued from page 341, Vol. III.) escapes, and then the pressure no longer acts on the sides at the orifices B, but only on the opposite sides at A, as seen in Wuen you see in a city, such as London, a space of ground the sketch on the right of the figure. The pressure which dug up to a certain depth, and surrounded by a hoard, that is, takes place at A being no longer balanced by the pressure on

an enclosure formed of a collection of boards fastened to posts the opposite point at B, acts upon the tube and on the whole driven into the ground, you then begin to think that a buildvessel so as to produce a motion of rotation in the direction of ing is about to commence, that a superstructure is about to be the arrow, in the sketch to the right of the figure; this motion raised, and that its foundation is in the process of preparation. being more or less rapid in proportion to the height of the You are still more convinced of the fact, when you see cartliquid in the vessel, and to the section of the orifices from loads of stone, brick, and lime deposited within the hoard, and which the water issues. The motion produced in this appara- workmen proceeding to prepare the mortar and stones or tus, is similar to that exhibited in the machine known by the bricks for the foundation. So it is in the system of Bookname of Barker's mill. The lateral pressure of water is applied keeping by Double Entry, which we are about to lay before in a useful and important manner in the construction of the you. We must begin with a series of Transactions in Business, hydraulic machines called Wheels of Reaction.

which are arranged in the exact order of their occurrence, as

the materials to be employed in forming a system or super. Hydrostatic Paradox.- We have already seen that the pres- structure which shall constitute a model for your guidance in sure on the bottom of a vessel full of liquid depends neither keeping the books of any Mercantile house in which you may on the form of the vessel nor on the quantity of the liquid, hereafter be engaged. We have selected the supposed transbut only on the height of the level of the liquid above the actions of a particular branch of Home Trade, namely, that of a bottom. Now, the pressure on the bottom of the vessel inust Cotton Merchant, as one well adapted, from its simplicity and not be confounded with that of the vessel itself on the body generality, to exemplify the principles which we have exwhich supports it. The latter is always equal to the whole plained in former Lessons. weight of the vessel and of the liquid which it contains; while transactions in order from January, when we suppose the

We have arranged these the former may be greater than this, less than this, or equal business to be commenced, till June, when we suppose a to it, according to the form of the vessel. This curious fact is Balance to be struck, and the Merchant's Real Worth ascercommonly known under the name of the Hydrostatic Paradox, tained. These six months' transactions in the Cotton trade because that, at first sight, it seems to be paradoxical, that is, are interspersed with various Banking, Bill, and Cash transcontrary to receive:i notions.

actions, such as might be supposed to occur in the business To explain this paradox, let Efen, fig. 26, be the vertical of a Cotton Merchant resident in the metropolis ; and the section of a vessel formed of two cylindrical parts in one piece, whole is afterwards entered in the various subsidiary books which but of unequal diameter. Let it be filled with water ; then as belong to such a business ; then into the Journal ; and, lastly, the horizontal pressures balance each other on all its sides, into the Ledger. The General Balance is then taken, and the these may be left out of consideration. The vertical pressure difference between the Assets and Liabilities, or the Real upon the bottom un, is equal to the weight of a column of the Worth of the Merchant, is ascertained from the Ledger alone. liquid which has this bottom for its base, and the height om The remarks which it will be necessary to make concerning for its altitude ; that is, this pressure is the same as if the the method of Balancing the Books, a process equivalent to the veggel had an io for its vertical section, and was completely taking of stock among tradesmen and others, who only use filled with water. This pressure is not wholly communicated Single Entry, we must postpone until we have shown how to to the body which supports the vessel; for according to the l make up the Subsidiary Books of our system.

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