ijo Cincinnati Society of Natural History. 



with closely fitted cast-iron plates, there being a heavy cast- 

 iron frame at the mouth, and the tunnel is furthermore lined 

 throughout with four courses (a total of i6 inches) of brick. 

 The excavation was made on three different benches. The 

 top one 9 feet high to the top of the arch, being always 

 extended ahead of the .second bench, S feet high, the work- 

 men in the latter bench being covered by a flooring, over 

 which the material excavated' from the top bench was con- 

 veyed backward on the small dump-cars. 



The excavation on the bottom bench, which measured 9 feet 

 vertically to the bottom of the invert, was not commenced 

 until the work on the other two benches had been nearly 

 completed. After the work was well under way the rock- 

 cutting was effected at a rapid rate, 338 feet of tunnel, 

 averaging 14 yards to the running foot, having been excavated 

 in 26>^ days. Shaft No. i, 2,650 feet from the portal, was 

 sunk 206 feet, and is 10 by 20 feet in .size, while .shaft Xo. 2, 

 of the same size and 196 feet deep, is 5,200 feet from the 

 di.scharge point. One hundred and forty feet of the shafts 

 were through hard ba.stard limestone, which overlays the 

 Niagara slate or Utica .shale, met with for the remaining 

 di.stance, and through which the main tunnel itself was 

 mostly made; its base, as it reached away from the river, 

 being in Queenstowne limestone. 



The largest turbine wheel now in existence is 500 horse- 

 power. Tho.se to be used by this company are to represent 

 5,000 horse-power each. The four polar dynamos, with drum 

 armatures, will be directly connected with the shafts of the 

 turbines, which will make 250 revolutions per minute. The 

 cost of water-wheels, exclu.sive of excavation and erection, 

 and also exclusive of pumps, compressors, and dynamos, is 

 given at $3.90 per horse-power. The wheels are to be 

 guaranteed at Ho per cent, efficiency, although the makers 

 expect 85 per cent. 



Contracts will be made to furni.sh power on the company's 

 grounds at the falls for 24-hour days according to the follow- 

 ing approximate .scale: For 5,000 hor.se-power, $10.00 per 

 hor.se-power; for 4,500, $10.50; for 4,000, $1 1. 00; and $20,00 

 for 300 horse-power; all under this being supplied by electro- 

 motors. 



