290 ANNUAL REPORT 
The illustration on page 289 shows a modern rotary kiln as erected 
by the Allis Chalmers Company. . 
The burning process proper is extremely simple. A fire is started 
with wood and as soon as this is burning briskly coal dust is blown in, in 
gradually larger quantities till the desired heat is being produced. The 
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Fig. 43. Diagram, showing method of feeding a rotary kiln, with dry powdered cement 
batch. 
eement mixture is then fed to the kiln in a regular supply and the 
burning thus begun, which is kept up for six days in the week until the 
lining shows signs of giving way. The clinker, in the shape of black 
roundish balls from the size of a pea up to that of a walnut, often con- 
sisting of aggregates which cling together in clusters, is discharged in a 
regular stream. The air required for combustion enters partly with 
