"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 66 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. 66 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, philosophical 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; particularly 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. Wedgwood 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.” 66 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 66 *Memoirs of Dr. Priestley, by 'himself,' p. 97. 1806. + Mr. Watt to Dr. Darwin, Bir mingham, January 3rd, 1781; 'Me'chanical Inventions of Watt,' vol. ii. p. 123. "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 "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,— 66 66 66 66 66 66 66 66 'Nymphs! your bright squadrons watch with chemic eyes "With playful force arrest them as they pass, he only says," Until very lately, water was esteemed a simple element, nor are all the most celebrated chemists of Europe yet converts to the new opinion of its decompo"sition. M. Lavoisier and others of the French school have "most ingeniously endeavoured to show that water consists of pure air, called by them oxygen, and of inflammable air, "called hydrogen, with as much of the matter of heat, or calorique, as is necessary to preserve them in the form of gas;" and he mentions that "The history of the progress "of this great discovery is detailed in the Memoirs of the Royal Academy [of Sciences] for 1781, and the experi"mental proofs of it are delivered in Lavoisier's 'Elements of "Chemistry. The results of which are that water consists " of eighty-five parts, by weight, of oxygen, and fifteen parts, by weight, of hydrogen, with a sufficient quantity of calorique." "* And again in a subsequent note, where, speaking of "the present important discovery of the production of "water from pure air, or oxygen, and inflammable air, or hydrogen," he says that one might be tempted to believe, from allegorical interpretations of the old mythology, “that "the very ancient chemists of Egypt had discovered the composition of water, and represented it in their hiero"glyphic figures before the invention of letters." † The subject is also referred to in another of Dr. Darwin's works, viz., his 'Phytologia;' where he says, "According to the theory "of M. Lavoisier concerning the composition and decomposi"tion of water, there would seem another source of thunder"showers; and that is, that the two gases termed oxygen gas "or vital air, and hydrogen gas or inflammable air, may exist "in the summer atmosphere in a state of mixture, but not of "combination; and that the electric spark, or flash of light 66 *Botanic Garden,' part i. canto iii. 1. 200-204; and note, vol. i. p. 152, ed. 1799. "ning, may combine them, and produce water instanta"neously." But nowhere does the highly imaginative and well-informed Doctor appear to have sought to associate his own name with the discovery on which he bestows such deserved admiration; and, indeed, the "composition" of which he writes, whatever may have been the force or the weakness of the impression which the idea of it had made on his mind, must be viewed as rather a transmigration from one substance into another, than as a compounding of two substances into one. Still, the "secret" he announces will be considered as no uninteresting addition to the literature of the late "water controversy;" valeat quantum valere potest. The Lunar Society lost one of its most active and valued members by the disgraceful riots which in 1791 had the effect of driving Priestley from his home; when his house, library, chemical apparatus, and furniture were destroyed by the cowardly violence of the rabble. On that occasion the extraordinary spectacle was presented, of an ignorant and brutal mob in England arming themselves against the partisans of democratic lawlessness in France. "The affair origi"nated," wrote Mr. Watt to his friend M. De Luc,t "from "some gentlemen very foolishly celebrating the French revo"lution by a dinner on the 14th. They were warned that "some tumult might ensue, and advised against it; however, some of them met, were insulted as they went in, "and, therefore, dispersed by five o'clock. About eight "o'clock a mob assembled, broke the windows of the hotel "where the company met, pulled down two dissenting meet❝ing-houses, then Dr. Priestley's house, which they razed to "the ground, (he and family made their escape in time); "they then destroyed a very good house in town, and from "that proceeded to destroy some others in town, and some "of the best houses in the country, mostly belonging to dis"senters, they say to the number of ten or fifteen, and to the "amount of above 100,000l. Then was the sovereignty of 66 |