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SLATE GEOLOGIST. 
In regard to the power consumed in operating elevators, screw 
conveyors and belt conveyors, Carpenter gives the following rules: 
W=weight of material moved per minute. 4 
l=distance moved per minute, in feet. 
llevators : 
WN is IN 
H.P.=—— KX —=——_— 
33000 8 264000 
Screw conveyors: 
WI! Aa vANN I 
H.P.=——_- x —=— 
33000 I0 330000 
Belt conveyor: : 
; Wil 2. Wl 
— —— 
~ 33000 8 26400 
Power Plant.—As the price of coal is constantly rising and the cost 
of the fuel is the heaviest item in the cost of manufacturing cement, 
manufacturers should give special attention to all coal saving prime motors 
and devices. The modern tendencies toward lowering the cost of power 
move in the following directions: 
I. Compound condensing engines, using superheated steam. 
Steam turbine and electric distribution of power. 
3. Gas engines and electric distribution of power. 
Ny 
The most radical decrease in cost is offered by the use of gas engines 
using generator gas. With the improvements of the modern gas engine 
the use of this type of motor is rapidly becoming a practical proposition 
and means a reduction in the cost of power of from 50 to 75 per cent., 
compared with the best and the average steam plants. One cement plant 
operating with gas engines using natural gas, the Iola Portland Cement 
Co., Kansas, is reported a perfect success. 
Transmission of Power. —It is now generally realized that long 
and heavy shafting is a source of loss of power and electric transmission 
has been rapidly adopted in many plants. This affords an ideal way of 
distributing power even though it is not cheaper in actual operation than 
shaft transmission. However, unless carefully protected the ordinary 
motor is bound to suffer through the dust and dirt always present in a 
cement mill. This difficulty is overcome by the induction motors which 
are now built practically dust proof. | 
Where large powers are transmitted by shafts, rope transmission 
should be used. 
The Cost of Making Portland Cement. —It is not the intention of 
the writer to quote estimates of cost given him by managers and superin- 
tendents of plants, for the reason that no figures which could be given 
