For lantern screen there is nothing better than a smooth wall finished off in flat white, but where this is impossible a rigid is preferable to a rolling screen as giving a surface free from folds and kinks. Screens should be kept perfectly clean, as dirt injures the effect of slides incalculably. The lantern itself should be of the electric arc variety, as being easy to manage and always ready with little delay, especially where the “direct” electric current is available. It is best installed in a room outside, or a gallery closed in from, the lecture room, the projection being made through an opening. An electric signal which provides at the platform a push for the use of the lecturer, and sounds a “buzzer” or flashes a small lamp in the operator’s apartment, is probably the best form of lantern signal. The chairs in lecture rooms should be as comfortable as means will allow, and should be fitted with rubber tips to ensure quiet. Quiet floor coverings should be used in the room, and, indeed, all fittings and furniture should produce that ease of body which will allow the mind to occupy itself exclusively with what is going on upon the platform. DIVISION VI BOOK SELECTION AND ACCESSION CHAPTER XIII BOOK SELECTION =174. General Principles.=--Although a great number of articles and papers have been written upon the subject of book selection, there still seems room for some remarks upon the general question from a standpoint somewhat different from the ordinary. Most of the articles which have come under notice deal with the mere routine of book selection--how to systematize the ordering of books; the work connected with preparing them for public use; the bibliographical side; the question of duplicating popular books; and other more or less mechanical aspects of the matter. The philosophy of book selection and questions connected with the policy of building up libraries have rarely been considered.