FIELD OPERATIONS - 353 



rial moves by gravity toward the lower end. The volume 

 of its output depends largely on the rapidity with which 

 the ingredients are fed into the mixer. 



QUANTITATIVE MIXERS 



Quantitative mixers are mixers that measure as well as mix 

 the ingredients used to make concrete. They usually con- 

 sist of continuous mixers similar to those just described, to 

 which is added a device for measuring automatically the 



FlG. 7 



cement, and broken stone as it enters the mixer. Some- 

 times the measuring apparatus and mixer proper are built as 

 one machine, and sometimes the measuring apparatus is 

 built separate, so that if may be used with any suitable mixer. 

 Gilbert Measurer and Feeder. A machine that can be 

 applied to any continuous mixer is the Gilbert accurate 

 measurer and feeder. Fig. 7 shows a view of this measurer. 

 At a are shown the bottoms of the three storage bins, which 



