Page:Graphic methods for presenting facts (1914).djvu/249

 Pins having spherical glass heads may be used on wall maps without any danger of the heads fading from sunlight. The glass surface is so smooth that dust cannot collect sufficiently to affect the color appearance of the pin head. Even if the map does get dusty, it is perfectly safe to use the feather duster on a wall map having pins which are pushed in so far that the spherical heads are in contact with the map surface. Dusting of such a map will not loosen the pins in any way. A wall map on which pins with spherical glass heads are used can be very cheaply mounted, it needs no glass cover, and the pins can be put in or taken out instantly, thus giving a location record which is at all times in plain view, yet thoroughly accurate.

Review of Reviews

Fig. 187. Location of the Plants Affiliated with the University of Cincinnati, College of Engineering. Every Star Represents a Plant Where Co-operative Engineering Students are Employed

A wall exhibit like this is easily made by using a red legal seal and red stars such as can be purchased at many good stationery stores

Another great advantage of the pins with spherical glass heads is that they may be obtained with small-diameter heads, which permit the use of numerous pins on maps of small size. In portraying many