Page:Graphic methods for presenting facts (1914).djvu/247



MAPS AND PINS

Pin maps have not been much used in the past, chiefly because a map pin which would give satisfactory service has not been available for common use. Until recently the map markers obtainable have been little more than old-fashioned carpet tacks having chisel-shaped points which cut the surface of any map into which they were pushed. Tacks with rough steel shanks cannot be pushed far into a map if the tacks are to be pulled out again. Also, rough steel is likely to rust so as to cause the whole tack to deteriorate rapidly.

Cloth heads on the map tacks make it possible to have tacks in distinct colors and plaids. The cloth tops, however, fade in the sunlight and collect dust so that in a short time the different colors of tacks on any map, exposed as a wall map must be, cannot be easily distinguished. The crudeness of the cloth-covered tack makes it unsatisfactory for many kinds of map work. Cloth-covered tacks are long, and long tacks which can be pushed only a short distance into the surface of a map are not satisfactory, for they are likely to drop out or be knocked off by any slight disturbance.

Wall maps with long projecting tacks are not practical for office use unless protected by an expensive frame with a glass cover. As it is usually necessary to open up such a glass map-case to change the position of the tacks frequently, the construction of the case becomes unduly expensive. Without a glass cover a wall map with long projecting tacks is likely to be damaged by the feather duster of the janitor.

Even when maps with long projecting tacks are safeguarded by being placed in separate drawers of a cabinet made for that purpose, there is still a probability that some of the tacks will come loose from the mounting and rattle around inside of the map drawers. This is a point not realized by most men who install map and tack systems, but it usually sooner or later sounds the death-knell of the tack system.