that he who endeavours to furnish something in its aid should devote his whole life to it, should survey and investigate it in all its extent; for this, in most cases, would be a severe condition even for the initiated. But if we look through the history of science in general, especially the history of physics, we shall find that many important acquisitions have been made by single inquirers, in single departments, and very often by unprofessional observers.
To whatever direction a man may be determined by inclination or accident, whatever class of phenomena especially strike him, excite his interest, fix his attention, and occupy him, the result will still be for the advantage of science: for every new relation that comes to light, every new mode of investigation, even the imperfect attempt, even error itself is available; it may stimulate other observers and is never without its use as influencing future inquiry.
With this feeling the author himself may look back without regret on his endeavours. From this consideration he can derive some encouragement for the prosecution of the remainder of his task; and although not satisfied with the result of his efforts, yet re-assured by the sincerity of his intentions, he ventures to recommend his past and future labours to the interest of his contemporaries and posterity.
Multi pertransibunt et augebitur scientia.
NOTES.
NOTE A.—Par. 18.
Leonardo da Vinci observes that "a light object relieved on a dark ground appears magnified;" and again, "Objects seen at a distance appear out of proportion; this is because the