NITRATES FROM ATMOSPHERE— SCOTT. 371 



were given. The turbines were designed to develop a maximum of 

 14,450 horsepower when working with a net head of 274 meters and 

 running at 250 revolutions per minute. The efficiencj- was to be 76 

 per cent when the quantity of water used was 5,200 liters per second. 

 When running under the same conditions of speed and pressure and 

 developing normally 13,000 horsepower, the efficiency was to be 78 

 per cent and the water used 4,G50 liters per second. When load was 

 suddenly thrown off to the extent of 25, 50, and 100 per cent, the 

 \ariations of speed were to be limited to 3.5 per cent, 7 per cent, and 

 17 per cent above normal and the maximum increase of pressure in 

 (he pipe line was not to exceed 15 per cent. 



All these guarantees were easily maintained. In May, 1911, the 

 pipe lines were filled and the turbine started for the first time. A 

 number of tests were then carried out, and about three months later 

 the definite taking-over tests of all the turbines were made by Mr. 

 Geheimrat Reichel, professor of the Charlottenburg Technical School 

 of Berlin. The output of the turbines was measured by electrical 

 means; the quantity of water used was measured by the " Schirm 

 methode" in the tailrace. The highest efficiency that was attained 

 was 82.6 per cent, with an effective turbine output of 11,000 horse- 

 power. With nozzles fully opened the maximum effective horse- 

 power of the turbines was about 16,000. 



The maximum increase of speed was 15 per cent, whilst the in- 

 crease of pressure above static head did not exceed 10 per cent. 



The five Escher Wyss turbines are each coupled to 3-phase gen- 

 erators, made by Brown. Boveri & Co., of Baden. 



At a power factor of 0.6 each machine gives 17,000 kva. at 11,000 

 volts, 50 periods per second. One of the machines gives the whole 

 of the 17,000 kva. 



Four of the units are of the double generator type, with a shaft 

 common to the two. The two armatures are separated by a fireproof 

 partition, so that if a coil of one should be burnt out the coils on the 

 other machine are not affected. 



Allowing for windage and friction, the guaranteed efficiency is 

 94.8 per cent for the double generator and 95.3 per cent for the single 

 generator. This is at full load and with a power factor of 0.6. 



The voltage difference from full load to no load and vice versa is 

 1,400 volts. This may be necessary by the conditions of working the 

 furnaces, as they are very subject to sudden changes. 



The total weight of one generator is 205,000 kilogi-ams (200 tons). 

 Ninety-two thousand kilogi-ams go to the rotating field and shaft. 

 The armature weighs about 90,000 kilograms. 



The armature stampings are held in position in the cast-iron 

 armature ring by vee grooves. Cast-iron rings clamp the stampings 

 at the ends and these rings extend to bottom of slots. The outside 



