[120] In illustration of the pious custom here alluded to by Sir H. Davy, it may be observed, that the vessels of the alchemists very commonly bore some emblem; such, for instance, as that of the cross; and from which, indeed, the word crucible derived its appellation.
[121] In addition to the anecdote already related of him, the following may serve to give a still greater force to this opinion. Soon after the appearance of Mr. Cavendish's paper on hydrogen gas, in which he made an approximation to the specific gravity of that body, showing that it was at least ten times lighter than common air, Dr. Black invited a party of his friends to supper, informing them that he had a curiosity to show them. Dr. Hutton and several others assembled, when, having the allentois of a calf filled with hydrogen gas, upon setting it at liberty, it immediately ascended, and adhered to the ceiling. The phenomenon was easily accounted for: it was taken for granted that a small black thread had been attached to the allentois,—that this thread passed through the ceiling, and that some one in the apartment above, by pulling the thread, elevated it to the ceiling, and kept it in that position. This explanation was so probable, that it was acceded to by the whole company; though, like many other plausible theories, it was not true; for when the allentois was brought down, no thread whatever was found attached to it. Dr. Black explained the cause of the ascent to his admiring friends; but such was his unaccountable apathy, that he never gave the least account of this curious experiment even to his class; and more than twelve years elapsed before this obvious property of hydrogen gas was applied to the elevation of air balloons, by M. Charles, in Paris.
I am indebted for this anecdote to the "History of Chemistry," a very able work by Dr. Thomson, constituting the third number of the National Library.
[122] "Reflections on the Decline of Science in England," page 15.
[123] While upon this subject, it is impossible not to notice the discoveries of Dr. Franklin, who combined in a remarkable degree a fertile imagination with a solid judgment; and the fruit of this union is to be seen in the invention of conductors for the security of ships and buildings against the effects of lightning. The philosopher who, predicating the identity of lightning and electricity, conceived the bold and grand idea of drawing it down from the thunder-cloud, an experiment which in another age would have consigned him to the dungeon for impiety, or to the stake for witchcraft, himself applied this wonderful discovery to the preservation of buildings, by the invention of pointed rods of iron. Of this invention it may be truly said, that he beat Nature with her own weapons, and triumphed over her power by an obedience to her own laws.
[124] Sir Humphry Davy has told us an anecdote which well illustrates this observation, while it affords a gratifying testimony of the kind feeling he entertained towards a kindred philosopher.—"There was—alas! that I must say there was!—an illustrious philosopher, who was nearly of the age of fifty before he made angling a pursuit, yet he became a distinguished fly-fisher, and the amusement occupied many of his leisure hours, during the last twelve years of his life. He indeed applied his preeminent acuteness, his science, and his philosophy, to aid the resources and exalt the pleasures of this amusement. I remember to have seen Dr. Wollaston, a few days after he had become a fly-fisher, carrying at his button-hole a piece of Indian rubber, when by passing his silkworm link through a fissure in the middle, he rendered it straight, and fit for immediate use. Many other anglers will remember other ingenious devices of my admirable and ever-to-be-lamented friend."—Salmonia. Additional Note, Edit. 2.
[125] Mr. Babbage considers it as a great mistake to suppose that Dr. Wollaston's microscopic accuracy depended upon the extraordinary acuteness of the bodily senses; a circumstance, he says, which, if it were true, would add but little to his philosophical character. He is inclined to view it in a far different light, and to see in it one of the natural results of the precision of his knowledge and of the admirable training of his intellectual faculties.
[126] This inestimable man died on his plantation at Nevis, on the 19th of October 1814, in the forty-eighth year of his age.
[127] I understand that the present Master, the Reverend Mr. Morris, has expressed his intention to apply the above sum to purchasing a medal, which he intends to bestow as a Prize to the most meritorious scholar.
[128] Simond de Sismondi, the celebrated author of the History of the Italian Republic.