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à prison. Now, however, science is no longer called upon to struggle against such attacks; but it must be confessed that, even in modern times, the progress of knowledge has been not a little retarded by the war-cry of innovation. When sir William Blackstone first began to deliver his law lectures before the university of Oxford, an attempt was made to cry him down as an innovator ; and in various ways he was made to feel the influence of established opinions. In an introductory lecture, which unfortunately has not been published, he thus forcibly and eloquently retorted upon his opponents:• In those scholastic days,' said the learned commentator, 'when the original and inquisitive mind of Roger Bacon was directed to the investigation of Nature's laws, the theological animus conspired against him, and he was accused of holding communion with evil spirits. Upon a particular occasion, when he intended to exhibit some curious experiments to a few select friends, the secret hav

ing got out, the whole town and all the colleges of the university were in an uproar. Priests, and fellows, and students were seen flying about in every direction, with their gowns streaming behind them, crying out, “no conjuror, no conjuror.” The cry of “no conjuror” resounded from hall to hall, from cell to cell. At a later day, Galileo was condemned by men, whose names are now remembered only as parts of the rubbish upon which the pedestal of his fame is raised. And in our times, there are men who seek to raise the cry of “no conjuror” against me. I tell you, you will soon find out, that these good people are, at least, no conjurors themselves.' *

Another obstacle mentioned by Bacon, (and the last which can be noticed in this sketch,) is,—that rare or remarkable phenomena have been principally inquired into; such as are common or trivial, being carelessly

* See Note (E.)

admitted without examination. Familiar acquaintance, it has been truly said, is perpetually mistaken for accurate knowledge;* and thus it is, that a patient attention to subjects that are known is as often needed as information on those of which we are ignorant. The history of science affords innumerable illustrations of the truth of this position. The vibrations of a lamp, suspended from the roof of the cathedral of Pisa, appearing to recur at equal intervals, arrested the attention of Galileo; who, having brought his observation to the test, by comparing the vibrations with the beat of his pulse, struck out the happy idea, that an instrument might be constructed which could be usefully employed by medical men (he was himself then studying medicine,) to ascertain, with a preçision not then attainable, the rate of the

* Abp. Whately's Political Economy, Lect. IX., and Logic, p. 332. Dr. Copleston has made the same remark in the Preface to his ‘Four Discourses,' xiii. See also Bacon's Works, vol. 2, p. 189.

human pulse and its variations from day to day. This led to the use of the pendulum as a measure of time. The lamp and its oscillations had been seen by thousands, and forgotten; but the youthful philosopher witnessed the phenomenon with thoughtful attention; and from a fact, apparently trivial, elicited one of the most valuable principles in science.

The history of the Voltaic pile affords another illustration, quite as striking as the last, of the importance in physical science, of not neglecting any phenomenon, however well known or apparently insignificant, for which we cannot account. The convulsive motion of a dead frog placed near an electrical machine, was a phenomenon which had long been known; but, until the time of Galvani, it had excited little or no philosophic inquiry. In 1790 that eminent anatomist turned his attention to the subject. His observations excited the curiosity of Volta, who, taking up the inquiry with great ardour, succeeded in constructing one of the most wonderful instruments invented by man—the Voltaic pile: an instrument which, in the hands of our illustrious countryman Sir H. Davy, effected a total revolution in chemical science.

Having suggested various grounds of hope that, notwithstanding the prejudices and errors of past times, knowledge would, in future, stretch forth her branches to the seas and to the floods,' lord Bacon concludes the first book of his Novum Organum with the animating reflection, that if to extend the power of our country over mankind,--an empire only to be gained by wrongs and human sufferings,--be an object of eager pursuit, how much nobler is that ambition, -if ambition it can be called, which seeks to obtain, by the pleasant and peaceful paths of science, dominion over Nature herself.*

* Novum Organum, lib. 1, aph. 129.

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