cunning impostors to aid their deceptions, or to produce a belief of their supernatural powers. But science snatched them from the hands of the ignorant and the designing, and having added the requisite improvements, bequeathed them to mankind as the means of future advancement in the paths of knowledge, and in the practice of the arts.

It may be laid down as a kind of axiom, to which few exceptions will occur, that great discoveries in science and improvements in art are never to be expected but as the result of knowledge combined with unwearied investigation. This axiom might be illustrated, were it necessary, from what we know of the past history of our most useful inventions. The celebrated M. Huygens, who first discovered the means of rendering clocks exact by applying the pendulum, and rendering all its vibrations equal by the cycloid -was one of the first mathematicians and astronomers of his age. He had long kept the object of his pursuit before his mind, he plied his mechanical ingenuity in adapting the machinery of a clock to the maintaining of the vibrations of a pendulum, and by his mathematical knowledge investigated the theory of its motion. By the aid of a new department of geometrical science, invented by himself, he showed how to make a pendulum swing in a cycloid, and that its vibrations in this curve are all performed in equal times, whatever be their extent.-The ingenious Mr. Robert Hooke, who was the inventor of spring or pocket watches, and of several astronomical instruments for making observations both at sea and land-was eminently distinguished for his philosophical and mathematical acquirements. From his earliest years he discovered a genius for mechanics, and all his other knowledge was brought to bear upon his numerous inventions

and contrivances.-Otto Guerieke, who invented the Air-pump, was one of the first mathematicians of his time; and the Honourable Robert Boyle, who improved this valuable instrument, was one of the most illustrious philosophers of the age and country in which he lived. Mr. Ferguson, the inventor of several orreries, the astronomical rotula, the eclipsarian, the mechanical paradox, and other astronomical machinery, had, from his earliest years, devoted the greatest part of his time to the study of mechanics, and the physical and mathematical sciences with which it is connected, as appears from the numerous popular works which he published on these subjects which are still in extensive circulation.-The late Mr. Arkwright, the inventor of the spinning jennies, devoted many years to the study of mechanics and to the improvement of his invention, till he was perfectly conversant in every thing that relates to the construction of machinery. This admirable invention, by which a pound of the finest cotton has been spun by machinery into a yarn extending more than 119 miles, was not the result of chance, but of the most unwearied study and attention in regard to every circumstance which had a bearing on the object of his pursuit and as he had not originally received any thing like a regular scientific education, his acquirements were the result of his own application and industry." The new process of refining sugar, by which more money has been made in a shorter time, and with less risk and trouble, than was ever perhaps gained from an invention, was discovered by an accomplished chemist, E. Howard, brother of the Duke of Norfolk, and was the fruit of a long course of experiments, in the progress of which, known philoso

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phical principles were constantly applied, and one or two new principles ascertained."

There are few inventions of modern times that have been more directly the result of philosophical knowledge and experiment than the safety-lamp, invented by that accomplished chemist, the late Sir Humphrey Davy. He instituted a series of philosophical experiments, with the express purpose of constructing, if possible, a lamp by which the miner might walk through a body of fire-damp in his subterraneous apartments without danger of an explosion; and the success with which his investigations were attended, led to one of the most beautiful and useful inventions which distinguish the period in which we live. Had this ingenious philosopher been ignorant of the nature and properties of carburetted hydrogen gas, of the composition of atmospheric air, of the nature of combustion, and of the general principles of chemical science, he could never have hit upon the construction of this admirable instrument, and the useful miner would still have been left to grapple with his invisible enemy (the fire-damp) without any means of escaping from its destructive agency.†

*See Appendix, No. IX.

It is more than probable, that fatal accidents have occurred in coal mines where these lamps have been used, owing to the ignorance and inattention of some of those artists who have been employed in forming the wire-gauze with which they are surrounded. A friend of mine, who performed a great variety of experiments with this instrument, with every combination of explosive gas, informed me, that, with a lamp surrounded with wire-gauze, manufactured by an artist in a town in the north of England, and who supplied it for the use of the miners—an explosion uniformly took place when the instrument was placed in a body of inflammable gas. He

We may farther remark, that the mechanic whose mind is enlightened with scientific knowledge, has a

suspected that the apertures in the wire-gauze were too large, and remonstrated with the artist on his want of accuracy; and it was not before he procured gauze with smaller apertures that his experiments succeeded; and they were attended with complete success in every future experiment, after the gauze was changed. So small was the difference in the contexture of the two pieces of the gauze, that, to a common eye, it was scarcely perceptible. It is found by experiment, that the apertures in the gauze should not exceed of an inch square, and that wire from to of a inch diameter is the most convenient. Had the artist alluded to known how to perform experiments with this instrument, and tried the effects of his gauze before he sold it for the purpose intended, such serious blunders would not have been committed. Who knows but the deficiency in the gauze alluded to might have been the cause of the destruction of several lives in the pits where it was used? for it is a certain fact that accidents from explosions are occasionally recurring, even in mines where these lamps are generally in use. Hence the necessity of chemical knowledge and attention to scientific accuracy in those who are the manufacturers of instruments of this description—on the accurate construction of which the lives and comforts of a useful body of the community may depend. I know not whether it be customary to put the safety-lamp into the hands of the miner, without first trying its efficiency for resisting the effects of explosive gases. If it is not, it is a most glaring and dangerous oversight; and there can be no question, that to the neglect of this precaution are to be attributed many of those explosions which have taken place in the mines where this lamp has been introduced. Besides, such neglects have a direct tendency to detract from the merits of this noble invention, to prevent its universal adoption, and to render un certain its efficiency for warding off destructive explosions. But from the experiments alluded to above, which were performed with the greatest care, and with every possible combination of explosive gas, and frequently exhibited in private, and before large public audiences—the efficiency of this lamp for resisting the effects of fire-damp is put beyond the shadow

much greater chance of being instrumental in improving the arts, than the mere chemist or philosopher. While the mere philosopher is demonstrating principles and forming theories in his closet, and sometimes performing experiments, only on a small scale, -the workman, in certain manufactories, has a daily opportunity of contemplating chemical processes and mechanical operations on an extensive scale, and of perceiving numberless modifications and contrivances, which require to be attended to, of which the mere scientific speculator can form but a very faint and inadequate conception. Being familiar with the most minute details of every process and operation, he can perceive redundancies and defects imperceptible to other observers; and, if he has an accurate knowledge of the general principles on which his operations depend, he must be best qualified for suggesting and contriving the requisite improvements. As the mechanic is constantly handling the tools and materials with which new experiments and improvements may be made,-observing the effects of certain contrivances, and of deviations from established practice and witnessing the chemical and mechanical actions of bodies on each other-he has more oppor

of a doubt. It is known to be the practice of some miners, occasionally to screw off the top of their lamp, in order to enjoy the benefit of more light than what shines through the wire-gauze. Such a practice ought to be strictly prohibited, and the instrument, if possible, rendered incapable of being opened at top-a practice which may probably have been the occasion of several explosions. If the workmen in mines were carefully instructed in the general principles of chemistry, and particularly in the nature of combustion, explosions, and the qualities of the different gases, they would not dare to hazard such dangerous experiments.