376 



CEMENTS, LIMES, AND PLASTERS. 



water or have been drained, the shovel is mounted on a car running 

 on tracks laid along the edge of the deposit. 



The material brought up to the dredge may be transported to the 

 mill in two different ways, the choice depending largely upon the manu- 

 facturing processes in use at the plant. At plants using dome or chamber 

 kilns, or where the marl is to be dried before sending to the kiln, the 

 excavated marl is usually loaded by the shovel on cars and hauled 

 to the mill by horse or steam power. At normal marl-plants using 

 a very wet mixture it is probable that the second method of transpor- 

 tation is more economical. This consists of dumping the marl from 

 the excavator into tanks, adding sufficient water to make it flow readily, 

 and pumping the fluid mixture to the mill in pipes. 



FIG. 80. Dredge at marl-plant. 



Marl-pumping. The following description of the Harris system 

 of pumping marl from the lake to the mill is taken from the catalogue 

 of the Allis-Chalmers Company: 



"This method of handling marl by compressed air is now in great 

 favor, and many plants have been and are now being installed in cement 

 works in this country and Canada. 



"The essential features are given in the diagram herewith, and 



