Sir Humphrey Davy, as he now was, married Mrs. Appreece, a woman of many talents and unusual intelligence. She was rich, and soon after their marriage Davy was able to resign his professorship at the Royal Institution, which he had held for twelve years, and devote himself to original research and to travel. Carrying a portable chemical apparatus for his studies, Sir Humphrey and Lady Davy went first to Scotland, and then to France, Italy, and Germany. They met the most prominent men of the age in those countries. These men found the famous chemist interested in everything about him, as much of a poet as a scientist. In Rome he wrote a sonnet to the sculptor Canova, and the literary circles of Italy proclaimed him a poet after their own heart. Davy was now one of the foremost chemists of the world, but he could as yet hardly lay claim to the title of inventor. He had been an ambitious man, and had once said that he had escaped the temptations that lay in wait for many men because of “an active mind, a deep ideal feeling of good, and a look toward future greatness.” That future greatness had always been in his thoughts, and had been one of the compelling powers in his great chemical discoveries. But beyond this thought of greatness was a very deep and earnest desire to help his fellow men. So when the chance to do this offered he took advantage of it at once. Explosions of coal-gas were only too common in the mines of England. They were almost always fatal to the miners, and formed the greatest peril of those who labored underground. In 1812 a terrible explosion occurred in a leading English mine, and caused the death of almost a hundred miners. The mine had caught on fire, and had to be closed at the mouth, which meant certain destruction to those within. The catastrophe was so great that the biggest mine-owners met to see whether some protection against such accidents could not be devised. After much discussion they appointed a committee to call on Sir Humphrey Davy and ask him to investigate the possibilities for them. Davy realized that here lay his opportunity to be of real service to men, the goal he had always had in mind. He took up the question, experimented with fire-damp, and found that it was in reality light carburetted hydrogen. He visited many mines, and took into careful consideration the conditions under which the men worked. For months he investigated and experimented, and at length, in 1815, he constructed what he called the safety-lamp. This was an oil lamp which had a chimney or cage of wire gauze. The gauze held the flame of the lamp from passing through and igniting the fire-damp outside. It was only possible for a very little of the fire-damp to penetrate the gauze and such as did was held harmless prisoner. The cage allowed air to pass and light to escape, and although by the combustion of the fire-damp the wire gauze might become red hot, it was still efficient as a safety-lamp.