That Davy was severely hurt by these attacks, is a fact well known to his friends. In a letter to Mr. Children he says: "A mind of much sensibility might be disgusted, and one might be induced to say, Why should I labour for public objects, merely to meet abuse?—I am irritated by them more than I ought to be; but I am getting wiser every day—recollecting Galileo, and the times when philosophers and public benefactors were burnt for their services." In another letter he alludes to the sycophancy of a chemical journal, which, after the grossest abuse, suddenly turned round, and disgusted him with its adulation. "I never shake hands," says he, "with chimney sweepers, even when in their May-day clothes, and when they call me 'Your honour.'"
While the trials above related were proceeding in the ports of England, the naval department of France was prosecuting a similar enquiry; and as experiments of this nature are conducted with greater care, and examined with superior science, in that country, it may not be uninteresting to the English reader to receive a detail of the examination of the bottom of La Constance frigate, in which the protectors bore a much larger proportion to the copper surface than was ever practised in the British navy. This document, I may observe, is now published for the first time.
"The inspection of the bottom of the frigate La Constance, has given rise to some interesting observations on the effect of protectors, and it has confirmed the fact before advanced of the great inconvenience which attends the application of too large a proportion of the protecting metal.
"The surface of this metal, which was of cast iron, placed on each side of the keel, and in long scarphs of iron plates situated towards the stem and stern-post and the water line, appeared to have been about the 1-30th part of the surface of the copper, instead of the 1-250th part as now practised.
"The galvanic action has been extreme, both in rapidity and intensity. The scarphs are entirely destroyed, and have absolutely disappeared; and we should have been ignorant of their having ever existed, had we not been informed of the fact, and observed dark stains which marked their position, and discovered the nails still entire by which they had been fastened.
"The plates, which were in the first instance about three inches thick, were covered throughout their whole length by a thick, unequal coating, spotted with yellow oxide. This was principally owing to the absorption of about twenty-five per cent. of its weight of water. Under this, the iron was as soft as plumbago, and there remained scarcely an inch of metal of its original metallic hardness.
"The bulky and irregular appendage (the protectors) at the lower part of the ship's bottom caused a great noise in the sea, in consequence of the dead water which it occasioned, and doubtless lessened the speed of the vessel. But that which contributed most to this unfortunate result, was the exceedingly unclean state of the copper, arising from the excess of the iron employed: this, carried to so great an extent, having the effect of extracting matter from the water, which, forming a concretion on the sheets, enabled the marine animals the more easily to attach themselves. The sheathing was covered with a multitude of lepas anatifera, shells with five valves, suspended by a pedicle of three or four centimetres long, collected into groups; of lepas tintinnabulum, a shell with six valves; of oysters with opercula; of polypi, &c. No part of the bottom was free from them.
"Below, the copper was certainly preserved from oxidation; and up to within a few sheets of the water line, it did not appear to be worn. But to save expense, it was obliged to be cleansed without removal, by rubbing it hard with bricks and wet sand, which has succeeded very well in restoring its copper colour."
The following is the description of shells above enumerated:—
Genus Anatifa, Encyclopedia.—(Lepas, Linnæus.)