It is said that the Marquis of Worcester’s attention was first accidentally directed to the subject of steam power, by the tight cover of a vessel containing hot water having been blown off before his eyes, when confined a prisoner in the Tower. He published the result of his observations in his ‘Century of Inventions,’ which formed a sort of text-book for inquirers into the powers of steam for a time, until Savary, Newcomen, and others, applying it to practical purposes, brought the steam-engine to the state in which Watt found it when called upon to repair a model of Newcomen’s engine, which belonged to the University of Glasgow. This accidental circumstance was an opportunity for Watt, which he was not slow to improve; and it was the labour of his life to bring the steam-engine to perfection. This art of seizing opportunities and turning even accidents to account, bending them to some purpose is a great secret of success. Dr. Johnson has defined genius to be “a mind of large general powers accidentally determined in some particular direction.” Men who are resolved to find a way for themselves, will always find opportunities enough; and if they do not lie ready to their hand, they will make them. It is not those who have enjoyed the advantages of colleges, museums, and public galleries, that have accomplished the most for science and art; nor have the greatest mechanics and inventors been trained in mechanics’ institutes. Necessity, oftener than facility, has been the mother of invention; and the most prolific school of all has been the school of difficulty. Some of the very best workmen have had the most indifferent tools to work with. But it is not tools that make the workman, but the trained skill and perseverance of the man himself. Indeed it is proverbial that the bad workman never yet had a good tool. Some one asked Opie by what wonderful process he mixed his colours. “I mix them with my brains, sir,” was his reply. It is the same with every workman who would excel. Ferguson made marvellous things—such as his wooden clock, that accurately measured the hours—by means of a common penknife, a tool in everybody’s hand; but then everybody is not a Ferguson. A pan of water and two thermometers were the tools by which Dr. Black discovered latent heat; and a prism, a lens, and a sheet of pasteboard enabled Newton to unfold the composition of light and the origin of colours. An eminent foreign _savant_ once called upon Dr. Wollaston, and requested to be shown over his laboratories in which science had been enriched by so many important discoveries, when the doctor took him into a little study, and, pointing to an old tea-tray on the table, containing a few watch-glasses, test papers, a small balance, and a blowpipe, said, “There is all the laboratory that I have!”