222 Popular Science Monthly 



A Ten-Thousand -Dollar Map of 



I 



N 



The map is a segment of a 90-foot globe, with heights and 

 depressions clearly represented. Every battlefield is shown 



Warring Europe 



the lobby of one of Chicago's large 

 office buildings is a huge relief map of the 

 European countries where the war rages, 

 exhibited to 

 the public 

 and lectured 

 upon by a 

 former war 

 correspon- 

 dent. The 

 main map is 

 io x 20 feet, 

 but owing to 

 its convex 

 construction 

 it contains an 

 area of 300 

 square feet. 

 It is a seg- 

 ment of a 90- 

 foot globe. It 

 was made by 

 William Rob- 

 ertson, with 

 the assistance 

 of ten men. 



It took them nine months to make it. 

 Including labor and materials, the cost of 

 the map is estimated to be $10,000. 



A special feature of the map is a system 

 of small incandescent lamps which are 

 flashed in connection with a large signboard 

 made up of two hundred small transparent 

 illuminated signs, each bearing the name of 

 an important point on the map. When the 

 lecturer mentions an important point 

 in the war territory a light 

 flashes at that point on the map 

 and simultaneously the name 

 is flashed on the large sign 

 which is located at the 

 left side of the map. 

 This makes it possible 

 for the spectator to 

 follow the lecturer 

 more closely and in- 

 telligently. 



The method used in 

 constructing the map 

 is interesting. A work- 

 ing model was first 

 made. From this the 

 frame was laid out, the 

 map scaled and the 

 countries outlined. The 

 vertical parts were next 



scaled and little pegs driven down for 

 measuring the mountains. A clay map 

 was then made on this frame and a cast 

 taken, from which the plaster of Paris 

 map (the one on display) was made. The 

 next task was to shave the map and gradu- 

 ate it, after 

 which the 

 various parts 

 were indi- 

 cated and 

 colored. At 

 the same time 

 the wiring 

 system for 

 the incandes- 

 cent lights 

 was installed. 

 The scale of 

 the map is 

 one inch to 

 every 7.8 

 miles . It 

 shows the 

 topographi- 

 cal detail of 

 every battle- 

 field. 



A simple bell-action attracts the arma- 

 ture and re-tightens the helical driving- 

 spring whenever the watch runs down 



An Electric Self- Winding Clock 

 for the Automobile 



WEAK-CURRENT electricity is in- 

 terestingly applied in the self-wind- 

 ing mechanism of a clock which has been 

 specially designed for the dashboard of the 

 automobile. A simple electromagnet is 

 made to drive the clock, and but three or 

 four batteries are required. 



In construction, this clock dif- 

 fers little from any other. 

 The gears, however, are 

 mounted to withstand 

 the jolts of traveling. 

 And instead of the or- 

 dinary hair-spring a 

 straight helical 

 spring furnishes the 

 motive power. The 

 armature of the elec- 

 tromagnet works 

 much like that of a 

 bell ; it tightens up the 

 driving-spring every 

 time it is attracted to 

 the magnet. The spring 

 loosens up while running 

 the clock, the armature 

 swinging slowly back. 



