Cl'JMENT FOR A MODERN STREET. 



^55 



is very economical of labor and is very uniform in its action, which 

 is an extremely desirable condition in the cement industry. 



I am indebted to the obliging courtesy of the officers of the Virginia 

 Portland Cement Co., of Craigsville, Augusta Co., Va., for the 

 accompanying illustrations of a Portland Cement Plant. 



Fig. 4 is a general view of the works, which it will be seen at once 

 are very unlike the natural cement works, at Milwaukee. All the opera- 

 tions of a Portland cement works are under cover. Fig. 5 represents 



Frc. 6. Ri)TAi:v Kiln? 



the stone house where the materials are received and sorted, preparatory 

 to being finely ground. A great variety of mills are used for grinding 

 both the crude materials and the cement clinker. So far as the 

 making of the cement is concerned, it does not matter in what kind of 

 a mill the ingredients may be ground, provided they be ground fine and 

 thoroughly mixed in the right proportions. If the mixture is burned 

 dry, the mixing is accomplished by the use of screens and sieves; if it 

 ic burned wet, the grinding is done in a wet mill, the paste being floated 

 ofE and allowed to settle in large tanks. The dry materials are blown 

 into the kiln. The wet mud is allowed to drip into the upper end of 

 the kiln as it is forced in by a pump. 



Fig. 6 represents the rotary kiln. It consists of a slightly inclined 

 steel cylinder, about 60 feet in length and 6 to 7 feet in diameter, 

 lined with fire-brick, and revolving by means of powerful gears at the 



