pleted, hills were to be levelled, and vallies filled up, to render them navigable with security[1].
In order to enable him to surmount the obstacles with which he foresaw he should have to contend, he retired to the house of his friend Signior Melzi, at Vaverola, not far distant from Milan, and there applied himself sedulously for some years, as it is said, but at intervals only we must suppose, and according as his undertaking proceeded, to the study of philosophy, mathematics, and every branch of science that could at all further his design; still continuing the method he had before adopted, of entering down in writing promiscuously, whatever he wished to implant in his memory: and at this place, in this and his subsequent visits from time to time, he is supposed to have made the greater part of the collections he has left behind him[2], of the contents of which we shall hereafter speak more at large.
Although engaged in the conduct of so vast an undertaking, and in studies so extensive, the mind of Leonardo does not appear to have been so wholly occupied or absorbed in them as to incapacitate him from attending at the same time to other objects also; and the Duke therefore being
