The practice of the greatest sculptors as regards the degree in which it has seemed desirable to them to take part in that mechanical portion of the business of producing a statue which consists in the manipulation of the marble, has always been very different. Some have subjected the marble to the touching of their own hands more, some less. The work of reproducing a copy of the clay model in marble is a purely mechanical one, and may or may not be in the artist's judgment best brought to perfection by the labor of his own hands. It will readily be believed, however, from what has been already said of the tendencies of Powers's talent and idiosyncrasy, that he was among those who have contributed most of their personal labor to the perfecting of their works. Powers was one of those men whose hands have faculty in them. He was a master in the use of them, and accordingly he loved to use them. It was his practice to go over with his own hand the surface of the marble of every work which left his studio. But he was not contented to do this in the manner and with the tools which had been used by so many generations of sculptors before him. That decided bent of his genius to mechanical invention which has been mentioned at the beginning of this paper led him to perceive that an improvement might be made in this respect. For giving the last finish to the marble, for removing from the surface a quantity so small that no chisel could be trusted to do the work, it is obvious enough to suggest the use of a file. And no doubt files are used for the purpose, but they are liable to a special and very troublesome source of inefficiency. They become clogged with the excessively fine dust of the marble in a very few minutes to such an extent as to be rendered useless, especially as the file must be of an exceedingly fine description. Powers therefore set his mind to the problem of inventing some means or some instrument by which this source of trouble could be avoided; and after considerable vexation, not so much in perfecting his own conception of the thing needed as in getting careless and not very competent workmen to execute his orders, he perfected a file of the necessary fineness upon the principle of a nutmeg-grater. His studio was at all times full of little ingenious contrivances of all sorts--contrivances for readily and conveniently modifying the light in the exact degree desirable; contrivances for the due collocation and distribution of artificial light; contrivances for the more ready moving of marbles, etc. etc.