Page:Library Construction, Architecture, Fittings, and Furniture.djvu/109

Rh and represents a book in the library. The numbers are arranged in movable groups of 250, running in tens across the face, instead of in hundreds from top to bottom as in other indicators. This allows an economical arrangement of numbers in classified indicators, especially in small libraries, where it is an advantage to allot only a few numbers at a time

to a particular class and allow it to expand, without at first purchasing a large number of separate frames. There is nothing, however, to prevent the indicator blocks being numbered in any manner preferred. Under each one-thousand indicator is a space intended to hold an indicator key or catalogue of the books, arranged in order of the indicator numbers.