It must be remembered, that most of these pins were in the characteristic blue colors commonly associated with the Bell Telephone System, and, because blue is almost impossible to photograph, the pins do not show out as strikingly as they would if other colors were used. The black splotches on the map were caused by the predominance in those areas of pins with dark blue heads. When this pin map was made there was no intention of taking a photograph of it. A much more distinct photograph would have been secured if pins in the contrasting colors of red, orange, black, green, purple, etc., had been chosen. All of these would have shown dark in the photograph, instead of white or light gray like the pale blue pins which in Fig. 194 were used in the greatest number.

Fig. 194 was photographed at an angle. The eastern half of the United States appears smaller than true scale because of the perspective in the picture. The perspective view shows that the glass-head pins had long shanks. This map, costing several hundred dollars to produce, could be injured severely by a few strokes of a janitor's feather duster. If short pins were used with spherical heads in contact with the map there would be no danger of the pins being misplaced. Another disadvantage of the long steel pins is that the steel portion exposed to the atmosphere is likely to rust, especially in cities near salt water. Pins with short needle-points pushed entirely into cork composition or corrugated straw-board have little opportunity to rust.