THREE:It is to be regretted that there have not been books especially prepared to instruct mechanical students in the relations between heat, force, motion, and practical mechanism. The subject is, of course, treated at great length in modern scientific works, but is not connected with the operations of machinery in a way to be easily understood by beginners. A treatise on the subject, called "The Correlation and Conservation of Forces," published by D. Appleton & Co. of New York, is perhaps as good a book on the subject as can at this time be referred to. The work contains papers contributed by Professors Carpenter, Grove, Helmholtz, Faraday, and others, and has the advantage of arrangement in short sections, that compass the subject without making it tedious.Attention has already been called to the fact that Epicurus, although himself indifferent to physical science, was obliged, by the demands of the age, to give it a place, and a very large place, in his philosophy. Now it was to this very side of Epicureanism that the fresh intellect of Rome most eagerly attached itself. It is a great mistake to suppose that the Romans, or rather the ancient Italians, were indifferent to speculations about the nature of things. No one has given more eloquent expression to the enthusiasm excited by such enquiries than Virgil. Seneca devoted a volume to physical questions, and regretted that worldly distractions should prevent them from being studied with the assiduity they deserved. The elder Pliny lost his life in observing the eruption of Vesuvius. It was probably the imperial despotism, with its repeated persecutions of the Mathematicians, which alone prevented Italy from entering on the great scientific career for which she was predestined in after ages. At any rate, a spirit of active curiosity was displaying itself during the last days of the republic, and we are told that nearly all the Roman Epicureans applied themselves particularly to the physical side of their masters doctrine.202 Most of all was Lucretius distinguished by a veritable passion for science, which haunted him even in his dreams.203 Hence, while Epicurus regarded the knowledge of Nature simply as a means for overthrowing religion, with his disciple the speculative interest seems to precede every other consideration, and religion is only introduced afterwards as an obstacle to be removed from the enquirers path. How far his natural genius might have carried the poet in this direction, had he fallen into better hands, we cannot tell. As it was, the gift of what seemed a complete and infallible interpretation of physical phenomena relieved him from the necessity of independent investigation, and induced him to accept the most preposterous conclusions as demonstrated truths. But we can see how105 he is drawn by an elective affinity to that early Greek thought whence Epicurus derived whatever was of any real value in his philosophy.
