tors waited on him to induce him to study the causes of the numerous explosions of fire-damp which were annually attended with fearful loss of life. He began his investigation by analyzing the gas and ascertaining in what proportions its mixture with air renders it most explosive. Having observed that the combustion was not communicated through tubes of small dimensions, he gradually reduced the length of the tubes till he found that a simple metallic gauze, with spaces not exceeding 122 of an inch square, was sufficient to prevent the burning gas on the one side from igniting the explosive mixture on the other. On this principle he constructed his "safety-lamp."
At the recent celebration of the centenary of Davy's birth, held at his native town of Penzance, it was remarked by one of the orators, a colliery proprietor, that but for the discovery of Davy's lamp some of the best seams of coal in England would have remained unworked, or could only have been worked at such cost that none but the rich could afford to use coal. "Davy's lamp," he further said, "is still the best, and if properly constructed, and used in conjunction with efficient ventilation, is an infallible guide to the presence of dangerous gases."
Urged to have his lamp patented, Davy made this noble reply: "My sole object was to serve the cause of humanity; and if I have succeeded I am amply rewarded in the gratifying reflection of having done so." In 1817 the colliery owners and miners of England presented Davy with a magnificent service of plate worth £2,500. This was bequeathed to the Royal Society by Lady Davy, who directed it to be sold and the proceeds applied to the encouragement of science.
In 1818 Davy was created a baronet. The same year he again visited the Continent, traveling extensively in Germany, Hungary, and Italy. The possibility of unrolling the Herculanean papyri engaged his attention while in Naples, and he published observations on volcanic phenomena, and on Oersted's electro-magnetic experiments. He was elected President of the Royal Society in 1820, and held that office for seven years. In 1823 he succeeded in devising a method of preventing the corrosion of the copper sheathing on ships' bottoms.
He now fell into ill health, and but little scientific work was done during the remaining years of his life. Three or four times he visited the Continent, but received little benefit from the change of scene and of climate. He died at Geneva, May 29, 1829, and there, in accordance with his own wishes, was buried. His widow founded a prize in his honor, to be awarded biennially by the Geneva Academy of Sciences for "the most original and important discovery in chemistry."
