146 



THE WORLD '8 AD VA NCE 



million cubic yards of concrete has been 

 used in the construction of the Arrow 

 Rock Dam. 



A series of views showing the new dam 

 and the river in its vicinity is repro- 

 duced on the foregoing page. The first 

 view, taken from the upstream side, 

 shows the reservoir which contained then 

 over 125 feet of water. The two cable- 

 ways were used for transporting work- 

 men and materials. The second view was 

 taken from a point above the south end 

 of the structure. It will be noted that 

 a section has been left out near the mid- 

 dle. The spillway will eventually be 

 on the far side, but it is still incom- 

 pleted, so that it was necessary for a 

 portion of the dam to be left open in 

 case of an emergency. The third view 

 was taken directly under the downstream 

 cableway and above the concrete mix- 

 ing plant. The cableway picks up the 

 concrete and transports it to the tower 



seen on top of the dam. The fourth 

 view was taken from the spillway side 

 looking across the downstream face. The 

 middle tier of outlet pipes is shown dis- 

 charging water. The mixing plant can 

 be seen directly above. The fifth view 

 was taken from the top of the dam and 

 shows discharge openings. The high 

 board fence was erected in front of the 

 mixers to ward off the spray. 



Thermophones were installed at dif- 

 ferent points in the concrete to indicate 

 the temperature of the mass as the work 

 progressed. A very interesting record 

 has resulted which shows the high tem- 

 perature of the setting concrete. This 

 record will have future value in enabling 

 engineers to study the expansion and 

 contraction of concrete. 



The total height of the dam is 350 feet. 

 90 feet of which are below the natural 

 river bed. 



THE ELECTRIQUETTE OR MOVING 

 CHAIR 



One of the interesting features of the 

 vSan Diego Exposition which is now being 

 held are the electric moving chairs or 

 electriquettes which enable the visitors to 



ride around without becoming tired. In 

 fact, these vehicles are very similar to 

 those that may be seen at many seashore 

 resorts, with the exception that electric 

 current serves as the motive power. 



Movable chairs were first used at the 

 Paris Exposition in 1889 an d since then 

 . they have made their appearance 

 at most of the expositions held in 

 different parts of the world. 

 However, these chairs were 

 crude affairs when compared to 

 the electriquette which requires 

 no "pusher." The person riding 

 about in the electriquette can 

 control the speed and direction in 

 much the same way as in the or- 

 dinary electric automobile. 



Vice-President Marshall Enjoying a Ride in an Electriquette. 



Increasing use of the national 

 forests by local farmers and 

 settlers to supply their needs for 

 timber is shown in the fact that 

 small timber sales on the forest 

 numbered 8,298 in 1914, against 

 6.182 the previous year. 



