Imágenes de página
PDF
ePub

CHAPTER XXIII.

PROPOSED UNIFORMITY OF WEIGHTS AND MEASURES THE LUNAR SO

CIETY DR. DARWIN PRIESTLEY RIOTS AT BIRMINGHAM MR, WATT'S JOURNEY TO PARIS AT THE REQUEST OF THE FRENCH GOVERNMENT-MACHINE OF MARLY BLEACHING BY CHLORINE — VISITS OF ROYALTY-INFRINGEMENTS OF STEAM-ENGINE PATENTS TRIALS AT LAW - PARTIES TO THE ACTIONS — ARGUMENTS AGAINST AND FOR THE VALIDITY OF THE PATENT OF 1769 — NATURE OF THE EVIDENCE — J. BRAMAH AND T TREDGOLD - VERDICTS IN FAVOUR OF THE PATENTEES - VALIDITY OF THE PATENT OF 1769 CONCLUSIVELY ESTABLISHED.

[ocr errors]

MR. Watt's chemical studies in 1783 having led him, towards the end of that year, to make some calculations from experiments of Lavoisier and De La Place, and to compare them with others made by Mr. Kirwan, he wrote to the latter gentleman,* "I had a great deal of trouble in reducing the

weights and measures to speak the same language; and many of the German experiments become still more diffi“ cult from their using different weights and different divi“sions of them in different parts of that empire. It is " therefore a very desirable thing to have these difficulties

removed, and to get all philosophers to use pounds divided “ in the same manner, and I flatter myself that may be accomplished if you, Dr. Priestley, and a few of the French

experimenters will agree to it; for the utility is so evident, " that every thinking person must immediately be convinced “ of it. My proposal is briefly this; let the Philosophical pound consist of 10 ounces, or 10,000 grains. the ounce

10 drachms, or 1,000
the drachm
100 grains,

100 “Let all elastic fluids be measured by the ounce measure of “ water, by which the valuation of different cubic inches will

a

or

* 14th November, 1783.

[ocr errors]

“ be avoided, and the common decimal tables of specific gra“ vities will immediately give the weights of those elastic “ fluids.

“ If all philosophers cannot agree on one pound or one grain, let every one take his own pound or his own grain; “ it will affect nothing except doses of medicines, which must “ be corrected as is now done ; but as it would be much “ better that the identical pound was used by all, I would

propose that the Amsterdam or Paris pound be assumed as “ the standard, being now the most universal in Europe : it “ is to our avoirdupois pound as 109 is to 100. Our avoir

dupois pound contains 7000 of our grains, and the Paris

pound 7630 of our grains, but it contains 9376 Paris grains, “ so that the division into 10,000 would very little affect the “ Paris grain. I prefer dividing the pound afresh to begin“ ning with the Paris grain, because I believe the pound is very general, but the grain local.

“ Dr. Priestley has agreed to this proposal, and has referred “ it to you to fix upon the pound if you otherwise approve of “ it. I shall be happy to have your opinion of it as soon as “convenient, and to concert with you the means of making “ it universal.

I have some hopes that the foot may be fixed by the pendulum and a measure of water, “and a pound derived from that; but in the interim let us at “ least assume a proper division, which from the nature of it “ must be intelligible as long as decimal arithmetic is used.”

“ As to the precise foot or pound,” he afterwards adds, in writing to Mr. Magellan, “I do not look upon it to be very “material, in chemistry at least. Either the common English “ foot may be adopted according to your proposal, which has “ the advantage that a cubic foot is exactly 1000 ounces, “consequently the present foot and ounce would be retained;

or a pendulum which vibrates 100 times a minute may be

adopted for the standard, which would make the foot 14.2 “ of our present inches, and the cubic foot would be very “exactly a bushel, and would weigh 101 of the present " pounds, so that the present pound would not be much “ altered. But I think that by this scheme the foot would

*

#

[ocr errors]

“ be too large, and that the inconvenience of changing all “ the foot measures and things depending on them, would be “ much greater than changing all the pounds, bushels, gal“ lons, &c. I therefore give the preference to those plans “ which retain the foot and ounce.” Alas, at the distance of three-quarters of a century from such philosophical and practical proposals, the prospect of a universal system of weights and measures seems almost as remote as that of a universal language !

About the time when Mr. Watt presented to the Royal Society his memorable "Thoughts on the Constituent Parts

of Water,'the neighbourhood of Birmingham was remarkable for the number of kindred spirits, all devoted to the pursuit of natural knowledge, and filled with mutual esteem and affection, who there found profitable pleasure in each other's society. Besides Mr. Watt, Mr. Boulton, and Dr. Small, there were among that number Dr. Darwin, Dr. Withering, Mr. Keir, Mr. Galton, Mr. Edgeworth, Mr. Day, and Dr. Priestley ;-all of them luminaries not unworthy to revolve round Watt as their central sun, but also shining with more than merely reflected light. “I cannot refrain,” says Edgeworth, ." from noticing the great variety of intellect which they pos“sessed. Mr. Keir, with his knowledge of the world, and good sense : Dr. Small, with his benevolence and profound

sagacity: Wedgwood, with his unceasing industry, experi“ mental variety, and calm investigation : Boulton, with his “ mobility, quick perception, and bold adventure: Watt, with “ his strong inventive faculty, undeviating steadiness, and un" bounded resource: Darwin, with his imagination, science, " and poetical excellence: and Day, with his unwearied re-"search after truth, his integrity and eloquence :-formed

altogether such a society, as few men have had the good “ fortune to live with; such an assemblage of friends, as fewer “ still have had the happiness to possess and keep through “ life.”. Withering's name is honourably distinguished in the annals of botany, as Priestley's is in those of chemistry;

66

* Memoirs of R. L. Edgeworth, 3rd edition, 1844, p. 117.

and of Mr. Galton, Priestley says that he had seldom, if ever, known any one of so cultivated a mind, such pleasing manners, and liberal dispositions.

Priestley came to reside at Birmingham in 1780; and, in repeatedly acknowledging the happiness he experienced in living near Mr. Watt, has thus noticed those monthly repasts of which his philosophical friends and himself partook at their respective houses in turn, and which became well known as the meetings of the Lunar Society. “I consider my settle“ment at Birmingham as the happiest event in my life;

being highly favourable to every object I had in view, phi

losophical or theological. In the former respect I had the “ convenience of good workmen of every kind, and the society “ of persons eminent for their knowledge of chemistry; par

ticularly Mr. Watt, Mr. Keir, and Dr. Withering. These, “ with Mr. Boulton and Dr. Darwin, who soon left us by re“ moving from Lichfield to Derby, Mr. Galton, and afterwards “ Mr. Johnson of Kenilworth and myself, dined together every “ month, calling ourselves the Lunar Society, because the time “ of our meeting was near the full moon,” * " in order,” as he elsewhere says, “ to have the benefit of its light in returning “ home.” From an invitation from Mr. Watt to Mr. Wedg. wood to attend one of the dinners of the Society, we learn that it was customary for the philosophic convives " to dine at “ two o'clock, and not to part till eight in the evening."

Mr. Watt, in writing to Dr. Darwin to remind him of his engagement to attend another of those friendly meetings, at once social and scientific, gives a lively bill of fare of the subjects proposed for the consideration of the party ;-some expressions used in which, viz., “it is to be determined “ whether or not heat is a compound of phlogiston and empyreal air," " what light is made of, and also how to make

it,” † as well as the still more curious ones of Darwin's reply, “I can tell you some secrets in return for yours, viz., " that atmospheric gas is composed of light and the earth of

66

* •Memoirs of Dr. Priestley, by mingham, January 3rd, 1781; "Mehimself,' p. 97. 1806.

*chanical Inventions of Watt,' vol. † Mr. Watt to Dr. Darwin, Bir- ii. p. 123.

[ocr errors]

a

« water (aqueous earth),—that water is composed of aqueous gas, which is displaced from its earth by oil of vitriol,may be held to have foreshadowed, with more or less distinctness, those researches which ended in the discovery of 6 what water is made of,” and also, as the discoverer quaintly expresses it, “how to make it." + Thus to Darwin, the general design of whose somewhat fantastic but often elegant poetry was, as he informs us, “ to enlist Imagination under “the banners of Science,” may now be assigned some of the credit of having been a pioneer in the march towards that great discovery :-a merit, however, which he never claimed for himself, both he and Mr. Watt having apparently given, at the time, no more than a passing attention to the shot thus fired, probably at random, but with a curious approximation to the mark which was afterwards effectually hit. For the speculation,—whether we call it imagination or science,– that water was a composite body at all ;-—that it was, in any

, way, composed of a “gas;" —which gas was “aqueous, dis

placed from its earth by oil of vitriol,” (a wonderfully fair description of the hydrogen of later days), was, no doubt, a “ secret” worth communicating, even though nothing was said either of another gas, or of explosion by an electric spark. It is indeed difficult to judge how far it may not have been one of those early seeds of the great discovery, which, afterwards germinating in the sagacious mind of Mr. Watt, bore their first-fruits in his celebrated conclusions communicated to Dr. Priestley and the Royal Society in 1783; and which were afterwards followed by the second and third harvests which Cavendish and Lavoisier respectively reaped,—or gleaned.

That Darwin never dreamt of claiming for himself, on the strength of such expressions, any share of the credit of the real discovery as to the compound nature of water, and its true constituents, appears from his poem, "The Botanic "Garden;' where, after describing the process of the formation of that fluid,

6

[ocr errors]

* Dr. Darwin to Mr. Watt, Jan. 6, + Mr. Watt to Mr. Fry of Bristol, 1781 ; Mechanical Inventions of p. 322, suprà. • Watt,' vol. ii. p. 124.

« AnteriorContinuar »