Sir Humphrey Davy isolated sodium and magnesium, which has led to the establishment at Patricroft near Manchester, of the manufactures of those metals. By the abstract researches of Hofmann and others upon Coal-tar, many new compounds were discovered, and the extremely profitable manufacture of the splendid coal-tar dyes was originated.

Scientific discovery is the most valuable in its ultimate practical results when it is pursued from a love of truth as the ruling motive, and any attempt to make it more directly and quickly remunerative by trying to direct it to immediately practical objects, decreases the importance of its results, diminishes the spirit of inquiry, and sooner or later reduces it to the character of invention. The greatest practical realities of this age had their origin in a search after important truths entirely irrespective of what utilities they might lead to.

I do not intend by these remarks to imply that any new trades or improvements in manufactures have been or can be effected without the labours of inventors and practical men, but that there should be a more judicious division of labour: one man to discover new truths, another to put them into the form of practical inventions, and the business man to work them; because it is proved by experience, that in nearly all cases these different kinds of labour require men of widely different habits of mind, and

that the faculties of discovery, invention, and practical working are very rarely united in one man.

Scientific investigations however, made in a manufactory, for the purpose of ascertaining the various sources of loss of materials, the circumstances which affect the amount or quality of the product; or made with the object of substituting cheaper or more suitable materials, or for varying their proportions, or for many other kindred objects, have in many cases resulted in great benefit to the manufacturer, and have formed the basis of successful patents. Some of the large brewers, chemical manufacturers, candle companies, and many others, constantly employ scientific men in this way to examine their materials, processes and products, and keep them acquainted with the progress of discovery and invention in relation to their own particular trades.

No art or manufacture is so perfect as to be exempt from the influence of discovery and invention, and no man can produce so perfect an article but that, by the aid of science, a better may be produced. Science and trade are mutually dependent, without the assistance of science, trade would be unable to supply our daily increasing wants, and without the pecuniary support of trade, science would languish and decay.

"As long as arts and manufactures are left to be directed and improved by simple experience, their progress is extremely slow, but directly scientific knowledge is successfully applied to them, they

bound forward with astonishing speed." Look at the art of taking portraits; for hundreds of years it remained entirely in the hands of oil and water-colour painters with but little progress in rapidity of production, but directly science was applied to it in the form of photography, its advance in this respect became amazing. Fifty years ago photography was almost unknown, but immediately Messrs. Daguerre and Talbot, in 1844, made known their processes, the new art began to advance, and so rapid has been its progress, that at the present time many thousand persons are employed in its exercise, and millions of portraits have been taken with an accuracy and at a cost quite beyond the reach of the old method.

Many persons hardly know the difference between science and art; a still greater number cannot readily distinguish between a concrete science and a pure one; and nearly all persons confound discovery with invention. A science may be conveniently defined as a collection of facts and general principles which are to be learned; an art as a collection of rules which are to be followed:—Art therefore is applied science; and every art also has a basis in science, whether that basis has been discovered or not. Scientific principles underlie not only manufacturing processes, but also sculpture, music, poetry and painting.

Discoveries differ also from inventions: a scientific discovery is a newly found truth in science, which in the great majority of cases is not in the form of