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but we shall touch upon Logarithms again, in our future Lessons in Algebra. Some instructions in Land-surveying have been given in vol. 1. of the P. E., see pp. 204 and 228; and in Mensuration, see pp. 172, 173, and 174 of the same volume. Euclid is coming faster now.]

MANUSCRIPT MAGAZINES.

SIR,-For some time past I have been studying English Grammar, and I think the more I study the less progress I make. Perhaps the reason I do not make any progress is, the want of some one to assist me. If five or six of the female students of the P. E. would agree to study Dr. Beard's Lessons in English, on the same plan as your correspondent T. J. proposes in No. 105, I should be very happy to join them. And you know if there was any thing we did not understand we might apply to you for instruction. What do you think, Sir? Would it not be a good way to obtain a correct knowledge of our own language? I wish (if it would not be too much trouble) that you will mention it in the P. E., as perhaps it would induce some one to come forward and act as conductress.

I am afraid I am giving you a large amount of trouble, but my desire to know more of my own language is great; and not having any one to assist me my difficulty seems double.

A VILLAGE GIRL.

Do you think I need study penmanship any more?—I am, etc.,
Barrowden, Rutland, 24th May, 1854.

ANSWERS TO CORRESPONDENTS.

ELIZABETH Cox (Killinchy Glebe, Co. Down, Ireland): Our fair student will see, by a glance at the Literary Notices, that her wants are anticipated, and that a Key to the Lessons in German is in the press. The reference mark to which she refers (62.2) means that in part ii., section 62, paragraph 2, further information will be found. All references of this nature are to the second part of the German Lessons, commencing p. 108, vol. iii. DULL (Sunderland): Many of his solutions are very fair; what he wished for he will have received by this time-a solution of the whole centenary. ALPHA (Reading) should buy Liddell and Scott.-EXCELSIOR: For the pronunciation of French words, see Cassell's French and English Dictionary. -J, H. EASTWOOD (Middleton) and A. J. PUGH (Longsight): Received.BLANDUS: His lines on the skylark never reached us.-A SUBSCRIBER (Rainbow-hill), whose initials we can't make out, is informed that all the numbers of the P. E. and of each volume are now in print, and may be had by order of any bookseller or agent.-R. D. DAVIS (Merthyr Tydvi) is quite right; the sum drawn on the 14th April should be £180 instead of £170, as entered in the Cash Book.-A. F. WILLIAMS (Epsom): The question No. 5, page 4, "Cassell's Algebra," is grievously misprinted. It should stand thus: "Find the numerical value of the expression

[blocks in formation]

b+c a+b

when a=4, b=3, and c=2."

G. BLAKELEY (Thornhill): His hints will be kept in view.-S., CARTER (Lincoln): His solution of the quadratic is very good, but it is not solved as required, that is, without the rule for quadratics.-DISCIPULUS (Liverpool): See the correspondence of T. G. Linstead.-J. GOODWILL (Grimsby) and C. SHELLEY (Clayton) want a good paper varnish for maps; who will help them to it?-OVENDENENSIS has sent us an apparently good solution of the "Four-Ball Question," but the principles of the solution are not fully stated.-F. SWEET (Bideford): His 34 solutions of the Centenary of Problems are very well; but the demonstration of the deduction from Prop. I., p. 246, line 27, vol. ii., P. E., is not correct, because he takes it for granted in his construction that those straight lines are equal which form the sides of the equilateral triangle inscribed in the circle; now this is the very thing to be proved.-R. PARKINSON (Everton): His solutions of an additional 25 problems belonging to the Centenary are very good.A. H. Wood (Gray's-inn Road): It usually takes about a month or six weeks before a correspondent can get an answer in the P. E., our correspondents are so numerous.-Our HEBREW friend at Bradford must not despair; Rome was not built in a day, and the P. E. cannot become a Cyclopædia in a twelvemonth!

J. K-G, A JUVENILE: The following was written by a little boy nine years of age, with a few alterations:

It was in our old house at home,

Upon my mother's lap,

That I was wont to sit me down,

And take a peaceful nap.

No troubles then e'er crossed my mind,

I was as bright and gay

As any butterfly, that flies

Upon a summer's day.

I often saw my mother weep,

And this did me annoy;

But when I qustioned her, she said

Go out and play, my boy.

Oh, mother dear, I cannot play,

While you are crying here;
Oh, let me get upon your lap,
And kiss away that tear.

Oh! then she wiped away her tears,

And on me sweetly smiled;

ran and kissed her lovely cheeks, She said, My child, my child!

Then fondly to her bosom pressed
My little form, and said,

Oh, Willie dear, remember me,
When I'm among the dead.

But, mother dear, you will not die,
And thus your Willie leave?
That you shall soon be called away

I can't, and won't believe.

But, ah! one month had scarce gone by,
When she was near her grave;

Oh how my little heart did wish
That I her life could save.

But, ah! that wish was all in vain,

For soon she went to rest;

And I shall never see her more,

Till I am with the blest.

'Tis now some twelve months since I've seen
The place I used to roam;

But now I'm going back again

To our old house at home.

But, ah! what pleasure can be there?

No mother will I find;

But strangers now must welcome me,

And some may be unkind.

There's but one spell that draws me there,

It is my mother's tomb;

I'll visit that, and then depart
From our old house at home.

LITERARY NOTICES.
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ON PHYSICS, OR NATURAL PHILOSOPHY.

No. XXXVIII.

(Continued from page 160.)

CALEFACTION.

Spheroidal State.-When liquids are poured on incandescent metallic substances, they present remarkable phenomena, which were first observed by Leidenfrost, about a century ago, and which have been since studied by some philosophers. It is to M. Boutigny d'Evreux, however, that we owe the knowledge of certain curious and important facts on this subject. It has been long known that when drops of water are thrown upon red-hot iron plates, they assume a globular form, and employ less time in vaporising in proportion to the degree of heat attained by the plates. This property, which has been carefully studied by M. Boutigny, is called by him calefaction; and the bodies found in such a state are said to be in the spheroidal state. If a capsule (a small cup) made of silver or platinum, of considerable thickness, be powerfully heated, and a few drops of water be dropped into it by means of a pipette, it is observed that the liquid does not spread itself, nor wet the capsule, as it does at the ordinary temperature; but that it assumes the form of a flattened globule. In this state the water takes a rapid gyratory motion at the bottom of the capsule, and not only does it refuse to enter into ebullition, but it vaporises fifty times more slowly than if it were in the boiling state. Moreover, if the capsule be cooled, there will happen an instant when it is not sufficiently hot to preserve the water in the spheroïdal state; its sides are then wetted by the liquid, and suddenly a violent ebullition takes place. All liquids may assume the spheroidal state, and the temperature of the capsule in which the phenomenon is produced is more elevated in proportion as the boiling point of the liquid is higher. Thus in the case of water, the capsule must be heated to, at least, 200° Cent. or 392° Fahr.; and in that of alcohol to 134° Cent. or 273°.2 Fahr. M. Boutigny has observed that the temperature of liquids in the spheroidal state is always lower than that of their state of ebullition, as in the following examples :

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Spheroïdal Temperature.
95.5 Cent. or 2030-9 Fahr.
75 .5
167 9
34
93 2
13 1

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spheroïdal state of liquids, it is supposed that the liquid globule is supported at a distance from the vessel by the tension of the vapour which is produced at its surface, so that the liquid not being heated by contact, but only by radiation, is converted into vapour very slowly; and the more so, because water being diathermous to rays emitted from an intense source, the greater part of the radiant caloric traverses it without heating it. M. Boutigny considers that the cause which hinders the liquid from wetting the metal is a repulsive force which is generated between the liquid and the heated body; a force which becomes greater in proportion as the temperature of the latter becomes more elevated. This hypothesis agrees with the following observation made by Mr. Perkins. A stop-cock having been placed on a steam-boiler below the level of the water within it, the liquid would not run out by the stop-cock, when opened, if the sides of the boiler were raised to a very high temperature, although the interior pressure was very great; but if the temperature of the sides was lowered, the liquid would rush out with considerable force.

In accordance with the results of these curious researches on the spheroïdal state of liquids, M. Boutigny has latterly connected the phenomena of calefaction with facts formerly deemed incredible, and which now-a-days are fully substantiated. It had been asserted that men ran bare-foot upon melted metal in an incandescent state, plunged their hands into melted lead, etc. Coupling these assertions with the stories of trial by fire, and incombustible men, he was desirous of verifying these phenomena. After some unsatisfactory efforts, he found that in founderies some workmen, more hardy than others, passed their fingers into incandescent cast metal; and some ran bare-foot upon a trough of melted iron which had just issued from the furnace, etc. He himself passed one hand right through a stream of red-hot iron about a quarter of an inch broad, and dipped his other hand into a vessel full of incandescent metal of the same description. He repeated this trial at the Mint in Paris, and plunged his hand, without hurt, into a mass of silver in a state of complete fusion. M. Boutigny considers that there is no contact between the hand and the metal; the perspiration with which the epidermis or under-skin is always more or less impregnated, passing into the spheroïdal state, reflects, without absorption, the radiant heat proceeding from the melted mass, and does not heat it enough to throw it into a state of ebullition. Whatever may be the explanation of these facts, well authenticated now, they completely account for the reality of the frequent success of the trials by fire, in the days of ignorance and barbarism.

DENSITY OF VAPOURS.

Sulphurous Acid (liquid) 10 5 Notwithstanding this reduction of temperature in the By the Density of a Vapour is meant the ratio between the spheroidal state, the temperature of the vapour produced by weight of a certain volume of that vapour and the weight of the liquids in this state is equal to the temperature of the the same volume of air, at an equal temperature and pressure. capsule; whence it follows that this vapour is not produced Two methods have been followed in the determination of the in the mass of the liquid. This property of liquids, by which density of vapours; the first, employed by Gay-Lussac, is they preserve a lower temperature than that of their ebulli- applicable to liquids which enter into the state of ebullition tion, has led M. Boutigny to the discovery of a remarkable below 100° Cent. or a little above it; the second, adopted by experiment, that of the congelation of water in an incan- M. Dumas, may be employed in the case of temperatures descent capsule. He heated a platinum capsule to a white which may rise to about 400° Cent. or 752° Fahr. The appaheat, and poured into it some drops of anhydrous sulphurous ratus of Gay-Lussac is represented in fig. 198. acid. This liquid, which boils at -10° Cent. or 14° Fahr., It is composed of a cast-iron vessel filled with mercury, in behaves in the capsule like water; that is, its temperature which a glass cylinder, M, is immersed; the latter is filled sinks below -10° Cent. If, then, there be added to the sul-with water or with oil, of which the temperature is indicated phurous acid, a small quantity of water, the latter, being cooled by a thermometer, T. In the interior of the cylinder is a by the acid, is instantly frozen; and the capsule being still graduated bell-shaped glass, c, which is at first filled with red-hot, we take out of it, to our great surprise, a piece of mercury. In experimenting with this apparatus, the liquid to be vaporised is introduced in a small glass bubble, repreIn the spheroidal state there is no contact between the sented at A, on the left of the figure; this bubble being then liquid and the heated body. M. Boutigny proved this by the hermetically sealed, it is weighed; and by subtracting from following experiment: he made a silver plate red-hot, and its weight thus found, its weight when empty, we have the placed it perfectly horizontal; he then poured on it some weight of the liquid it contains. The bulb is then introduced drops of water coloured black, and this liquid passed into the into the glass c, and the apparatus is gradually heated until spheroidal state: next, he placed the flame of a candle at a the water in the cylinder reaches a temperature higher by certain distance, in a line with the plate, when the flame was some degrees than that at which the liquid in the bubble distinctly visible, for some time, between the spheroid of water would enter into the state of ebullition. The bubble then and the plate. Whence he concluded that the liquid was bursts by the expansion of the liquid it contains, and by the kept at a small distance from the plate, or that it made its tension of the vapour into which it is converted, the mercury vibrations so rapid that the eye could not distinguish them. in the glass is depressed, as shown in the figure. It is necessary that the bubble be so small as to allow of all the liquid

ice.

[graphic]

In

VOL. V.

all the liquid is vaporised, the tapering point of the neck is hermetically sealed, the temperature of the bath and the height of the barometer being noted at that instant. Lastly,

introduced into it being converted into vapour. This conver- moment when the jet of vapour stops, which takes place wher sion completely takes place when the bath, having reached the temperature of ebullition which belongs to the liquid enclosed in the bubble, the level of the mercury is still a little higher in the interior of the glass than on the exterior. This, indeed, shows that there is none of the liquid remaining unvaporised; otherwise, the interior level would be a little lower than the exterior level. We are, therefore, sure that the weight of the liquid which was in the bubble, exactly Fig. 198.

Fig. 199.

[graphic]
[graphic]

represents the weight of the vapour which is formed in the glass c. As to the volume of this vapour, it is ascertained by means of the graduated scale on the glass. We have only now to calculate the weight of a volume of air equal to that of the vapour, and to divide the weight of the vapour by that of the air; the quotient is the density or the specific gravity required.

The process which we have thus described is not applicable to liquids whose boiling points exceed 150° or 160° Cent., that is, 302 or 320° Fahr. The reason is, that in order to raise the oil with which the cylinder is filled to these temperatures, the mercury, in the vessel must be heated to a degree considerably higher, a degree at which it produces vapour from the mercury which it would be dangerous to inhale. Besides, in the graduated glass vessel, the tension of the mercurial vapour would increase that of the vapour which is the subject of experiment, and would thereby become a source of error in

the result.

The following process, invented by M. Dumas, can be employed at any temperature up to that at which the glass would become soft and flexible, that is, about 400° Cent. or 752° Fahr. The apparatus is composed of a hollow glass globe, B, with a tapering neck, fig. 199, and capable of holding about a pint of water. This globe is completely dried within and without, and weighed when it contains air only, which gives r the weight of the glass. The liquid to be vaporised is then introduced at the tapering point, and the globe is next immersed in a water-bath saturated with salt, or in a bath of neat's-foot oil, or of D'Arcet's alloy, according to the temperature of the ebullition of the liquid contained in the globe. In order to keep the latter in the bath, there is fixed on one of the handles of the pot or vessel which contains it, an iron rod which is furnished with a sliding support of the same metal. The support carries two rings, between which the globe is placed, as shown in the figure. On the other handle is fixed a rod of the same kind, which carries a thermometer, D. The globe and the thermometer being immersed in the bath, the latter is heated a little beyond the boiling point of the liquid in the globe; then the vapour, as it issues through the extremity of the neck, drives out the air in the apparatus; and, at the

when the globe is cooled and carefully wiped, it is weighed
again, and the weight, P', thus obtained, represents the weight
of the vapour it contains plus the weight of the glass, minus
the weight of the air displaced. To obtain the weight of the
vapour, therefore, we must subtract from the weight p' the
weight of the glass, and add to the remainder the weight of
the air displaced, which will be easily done after the volume
of the globe has been found. To determine this, the neck of
the globe is immersed in the mercury, and its extremity is
there broken off with a pair of small pincers. As the vapour
is condensed, there is a vacuum created in the globe; and the
mercury rushes into it by the pressure of the atmosphere, and
completely fills it, if all the air has been forced out of it.
Then by pouring into a graduated vessel, the mercury which
fills the globe, we determine its volume at the ordinary tem-
perature. By calculation we easily deduce from this, the
volume of the vapour at the temperature of the bath, and con-
sequently the volume of the vapour at the same temperature.
Having ascertained by this process, as well as by that of
Gay-Lussac, the knowledge of the weight of a certain volume
of vapour, at a determinate temperature and pressure, the
density of the vapour may be ascertained by calculation. If
any air remains in the globe, it will not be completely filled
with the mercury; but the volume of mercury introduced
will still represent the volume of the vapour. The following
table shows the densities of some vapours as compared with
that of air, at temperatures a little higher than that of the
boiling points of the liquids from which they are generated:-

Table of the Densities of Vapours.
Vapours.
Common air
Vapour of water

Densities. 1.0000

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0.6235

do. alcohol

1-6138

do.

sulphuric ether

2-5860

do.

sulphuret of carbon

2.6447

do.

essence of turpentine

5.0130

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6.9760

8.7160

Problem 1. To find the density of a vapour when the weight of the vapour in grains, its volume in cubic inches, its tempe rature in Centigrade degrees, the height of the barometer, and the height of the mercury in the bell-shaped glass are given.

Let p denote the weight of the vapour in grains, e its volume in cubic inches, t its temperature in Centigrade degrees, H the height of the barometer in inches, and the height of the mercury in the glass vessel also in inches; it is required to find D the density of the vapour.

At 0° Centigrade, and at the standard atmospheric pressure, 61 cubic inches of air weighs twenty grains, p. 242, vol. iv.; consequently one cubic inch weighs f of a grain, and the weight of the volume of air is v. In order to find the weight of the same volume of air at the temperature t, let a be the co-efficient of the expansion of air; then the volume will be increased from 0° to to in the ratio of 1 to 1+at; on the contrary, the weight under the same volume, varies in the inverse ratio of 1+at to 1. Therefore, the weight of the volume of air, at the temperature t, and under the standard pressure, is (A). But the weight of the same 61 (1 + at) volume of air being proportional to the pressure, we pass from the standard pressure, which we denote by s, to the pressure H-h, - by multiplying the quantity (A) by the fraction

20 v

20v (Hwhich gives h) for the weight p' of a volume 618 (1 + at) , at the temperature f, and at the standard pressure.

sequently, we have for the required density, D =

61ps (1+at)

20v (H)

S

of air

Con

=

Problem 2. To find the volume of a given weight of vapour in the state of saturation, at a given temperature, its density being known. Let it be required to find the volume of twenty grains of the vapour of water at 100° Centigrade and at the standard pressure, the density of this vapour with relation to that of air being 06235. In order to find the weight of a cubic foot of the vapour of water at 100° Centigrade, in other words, of steam at the standard pressure, we must multiply the weight of a cubic inch of air at the same temperature and pressure by 06235. Now we have seen that representing by Pthe weight of a certain volume of air at t° Centigrade, by r the weight of the same volume at 0° Centigrade, and by a the co-efficient of the expansion of air, we have PP' (L+ a t), see p. 126, vol. v.; therefore P P Whence, in the case under consideration the weight of a cubic inch of dry air at 100° Centigrade 61 (1+0003665 X 100) 24 of a grain; consequently, the weight of a cubic inch of saturated vapour at 100° Centigrade, or steam, at the standard pressure, is 21 X 0 6235014964 of a grain. Whence the volume v of twenty grains of steam is

is

20

0.14964

20

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133 65 cubic inches.

In conclusion, we may observe that at 0° Centigrade a cubic inch of water weighs nearly 253 grains, and when this is converted into steam, or vapour at 100° Centigrade, without loss, it will still weigh the same; therefore, we have this proportion, as twenty grains: 253 grains :: 133-65 cubic inches: 1690 66 cubic inches, the volume occupied by a cubic inch of water when converted into steam. Hence, we see that the vapour of water at 100 Centigrade and at the standard pressure of the atmosphere, occupies nearly 1700 times the volume of the water which produced it; so that mechanics are accustomed to say, in round numbers, that a cubic inch of water produces about a cubic foot of steain.

BIOGRAPH Y.-No. XIV. JAMES WATT, INVENTOR of the STEAM-ENGINE. The celebrated James Watt was born at Greenock, formerly the port of Glasgow, on the 19th January, 1736, of a family said to have been remarkable for mathematical talent. His father was an active and respectable merchant of that town, and was one of its magistrates for many years. Young Watt

was prevented from receiving much benefit from the dayschools of his native town, by the extreme delicacy of his constitution, a physical defect which adhered to him through life. A defect of this kind, indeed, is one of those predisposing circumstances which scarcely ever fail to exercise a powerful influence on the future fortunes of the individual. How many of the most eminent artists, poets, and philosophers who adorned the age in which they lived, have been indebted to such apparently unfortunate accompaniments of birth, for that power and depth of reflection which have afterwards immortalised their names. Take the following instances. Pope, "who lisp'd in numbers, for the numbers came," was forced by the delicacy of his constitution to look for enjoyment chiefly in the retirement of domestic life; Pascal, Fontenelle, Samuel Johnson, and a host of other illustrious men, have found their only relief from the pains of disease in the absorption of mind induced by literary and philosophical studies. In later times, the illustrious examples of Scott and Byron are well known, and serve to confirm the assertion made by judicious and experienced writers, that occasional defects and weaknesses of the physical frame are amply compensated by the grasp of mind and the development of talent which arise from study, and from the reflective habits consequent on retirement from the world's gay scenes of fancied enjoyment. No doubt, those intensely studious habits which distinguished Watt during his long career, may in a great measure be attributed to the delicacy of his constitution in early life, to which we have alluded.

purpose of learning the business of a mathematical instrument At the age of eighteen young Watt went to London for the maker; and during a stay of twelve months, he made very considerable proficiency in various branches of mechanical art. Some time after his return from the metropolis, when he was maker to the University of Glasgow," then celebrated for the only twenty-one, he was appointed "Mathematical Instrument ability and reputation of its professors, and adorned by the Geometry, Dr. Adam Smith, the founder of Political Economy, illustrious names of Dr. Robert Simson, the restorer of ancient and Dr. Black, the able co-adjutor of Priestley, Scheele, and Lavoisier, in erecting the noble fabric of modern Chemistry.

Whether it was that his occupation did not find him sufficient employment, or whether it was that the weakness of his

health and constitution had an effect on his movements, it is difficult now to say, but we have heard from some of the old inhabitants of Glasgow, persons of a similar turn of mind to Watt himself, that he was remarked by his neighbours in the vicinity of his workshop to be a very lazily-inclined young man, and that if he continued to be so idle as they thought he was, he never would do any good. His workshop was situated at that time in King-street, and there, no doubt, he performed the experiments which afterwards conferred so much renown on his name We have been told, on the same authority, that he would get upon the roof of his workshop, and bask in the sun for half the day, apparently. doing nothing; but it is evident that while his body was thus at rest, his mind was deeply occupied with some philosophical inquiry. Let not, therefore, young persons of a thoughtful turn of mind be always judged too harshly, should they not appear to be so actively engaged as they ought to be.

The

It was during his residence in Glasgow under these circumstances, that Mr. Watt was employed by the Professor of Natural Philosophy, to repair a model of Newcomen's steamengine, for the purpose of exhibiting it to the students in working order. This took place in the year 1763. difficulty which he found in supplying the engine with steam, first suggested to him the idea of making a separate con denser; and by means of a set of experiments, which he made on the occasion, he was enabled to ascertain the exact quantity of heat consumed in the vaporisation of water. For some account of the various methods which Mr. Watt adopted in bringing the steam-engine from one step of improvement to another, the mechanical ingenuity which he displayed in varying the forms of the materials of the different parts of its machinery, and the philosophical facts which be established by his numerous and well-conducted experiments, see "Cassell's History of the Steam-Engine." It is of great importance to make this remark for the encouragement of plodding industry, that scarcely any of his improvements could be attributed to

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I those changes which ended in the of the steam-engine, are solely to be kill as an artist, and to his profound ale the grimaces of chemistry and mechanics. 1, h.. there met in one individual such a comad sagacity, practical ingenuity, and real If, however, it may not be amiss to observe that mcm wakinen have, by constant reading, deep study, bervation, acquired a knowledge of art and d only lar beyond their equals, but surpassing even The wire college bred, and who enjoyed much more cicable opportunities for learning. Of such individuals, the Vore plakaophical bakers of Glasgow, to whom we were mehbood for the preceding anecdote of Watt, were remarkable We have seen their shop filled with the ingenious kors of knowledge in that city; we have seen them take a handful of flour, scatter it equally over a board, like the band of the ancients, and portray the parts of a steam-engine upon it with the finger, in order to explain the principles of operation, as discovered by Watt, as improved by others, or as suggested by themselves. We have seen them portray the parts of a telescope or other optical instrument, and explain the principles of operation in the same way, to their admiring friends. Nothing came amiss to them and to their philosophical flour-board; they had something to say on every mechanical or chemical subject that could be named; and they were held in universal esteem. But fortune smiled on them; wealth was left to them by a relative; they retired from business; and the coterie of philosophical friends which used to meet in their shop was broken up.

To return to our memoir. Mr. Watt, in 1765, entered into partnership with Dr. Roebuck (the founder of the Carron Iron Works, Scotland), for the purpose establishing a manufactory of steam-engines. This object, however, was not immediately accomplished; the causes which prevented this were the embarrassments in which Dr. Roebuck became involved, and the constant employment which Mr. Watt began to enjoy as a civil engineer.

kingdom. Among other inventions of this ingenious man, was a copying apparatus, for which he took out a patent; and amid the multifarious concerns of an extensive business, he gave close attention to the new discoveries in chemistry, which were changing the face of that science; and he himself added to its domain, by the discovery of several remarkable properties of the gases. In 1756, he introduced into this country the new method of bleaching by chlorine (or oxymuriatic acid) discovered by M. Berthollet. This discovery he communicated to his father-in-law, Mr. Macgregor, a bleacher in the neighbourhood of Glasgow; and he himself not only gave directions for the proper construction of the necessary vessels, but superintended the first trials that were made in the process. The successful result of these trials is well known, as well as the astonishing advances which have been made in our manufactures by the discovery. Besides these more important subjects, there were few practical arts which he did not cultivate and improve, and with which he was not intimately conversant,

For several years of his life, Mr. Watt was harassed by the necessity of defending his patents against a host of invaders; but the validity of his claims was finally decided by the Court of King's Bench in 1799; and in the following year, he retired from business. He still continued after that period to interest himself in the progress of science, literature, and the arts; and till the end of his life he was always ready to give assistance and advice to others. Notwithstanding his very delicate constitution, by temperance and good management, he reached the advanced age of eighty-four, with his faculties unimpaired. After a short illness he expired at his seat in Heathfield, Staffordshire, on the 25th of August 1819. He was chosen a Fellow of the Royal Society of Edinburgh in 1784; of the Royal Society of London in 1785. The degree of Doctor of Laws was conferred on him by the University of Glasgow in 1806; and he was chosen in 1808, Corresponding Member, and afterwards one of the eight Foreign Members, of the Royal Institute of France.

On the 18th of June, 1824, a public meeting was held in In 1767, he was engaged on the survey of a proposed junc- London for the purpose of erecting a monument to the memory tion canal between the Forth and the Clyde, and afterwards of this illustrious man. At this meeting, the first men of the he made the survey of the canal between the Monkland age met and made the most eloquent speeches in honour of collieries and the city of Glasgow, a work of which he also the inventor of the steam engine. The talented and eloquent superintended the execution. He likewise made surveys of a Francis Jeffrey, editor of the "Edinburgh Review," and afterproposed canal between Perth and Forfar, and drew up a wards Lord Advocate of Scotland; the celebrated Henry report of another between the Clyde and the Western Ocean, Brougham, afterwards Lord Chancellor of England; and many across the isthmus of Crinan. It would be too long to enume- other noblemen and gentlemen, spoke on this occasion. rate here the various surveys, plans, and estimates which he This splendid meeting many of our readers will no doubt made, for the making of canals, the deepening of rivers, the remember, and they have most likely treasured up some of building of bridges, and the construction of harbours. The the fine sayings uttered on that memorable occasion. In the last line of country which Mr Watt surveyed for a canal, was following November, there was also held a public meeting in that between Fort William and Inverness, being part of the Glasgow for the purpose of erecting a monument to Mr. Watt Caledonian Canal, a project which was afterwards undertaken in that city or in its vicinity. As the men who spoke at this and carried into effect by Mr. Telford, the celebrated engineer. meeting were more intimately acquainted with Mr. Watt than Not long after he made this survey, he accepted the invitation the former, and as Glasgow was the scene of his early labours of Mr. Boulton of Soho, near Birmingham, and settled in and inventive genius, we may be permitted to lay before our England. In 1775, he obtained an extension of the term of readers a few of the facts and sentiments brought to light on the patent which he had taken out for his improvements, and that occasion, by giving some extracts from the speeches then the business of manufacturing steam-engines was at last begun and there delivered, from a document now lying before us. by Messrs. Boulton and Watt. The immense saving obtained The Lord Provost of Glasgow, who was in the chair, said: by this powerful engine soon caused its speedy adoption not "That as the idea of erecting one grand monument to the only in the mines of Cornwall, but in those of England gene-memory of Mr. Watt, in Westminster Abbey had not sucrally. During the years from 1781 to 1785 inclusive, Mr. Watt took out a number of patents for successive improvements in mill-work connected with his engines, such as the movement of the sun and planet wheels, the working on the expansive principle, the double-acting engine, the parallel motion, and the smokeless furnace. The machine was finally brought to perfection by the application of the centrifugal regulating force of the governor. In the whole of these inventions, and the contrivances necessary to give them full effect, we are impressed by a union of philosophical research, physical skill, and mechanical ingenuity, which has, we believe, no parallel in modern times.

The perfection thus given to the rotative steam-engine soon led to its general application for imparting motion to almost every species of mill-work and machinery; and thus an impulse, unexampled in the history of inventions, was given to the manufactures, the population, and the wealth of the

ceeded, he hoped that it would be superseded by the more successful efforts of that day, and by their contributions to the erection of one which would at once perpetuate his memory and adorn the city which gave birth to those mighty efforts of his genius,-his improvements on the steam-engine."

Professor Jardine said: "My Lord, I am one of the earliest and certainly one of the oldest friends of the late Mr. Watt. I had the happiness of living with him in habits of intimacy and friendship the greatest part of my life. I was particularly acquainted with him at the period when he was engaged in prosecuting those discoveries which have set him so far above all other men as an inventor in the arts. I then enjoyed much of his confidence, and was present at many of his early experi ments. When Mr. Watt had made such progress in his invention as to afford a favourable prospect of the result, he found that other experiments must be made to satisfy the public, on a larger and much more expensive scale than he was

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