THE MILK CONTRACTOR 



321 



It thus appears that in plants using the same type of machinery there 

 is a wide variation in the amount of work done. It is evident, too, that 

 there is a wider variation in the number of bottles filled per hour than in 

 the number filled per man per hour. This is partly explainable by the 

 fact that in some plants more men than necessary were working on the 

 machines. 



Taking into account the overhead charges, interest being figured at 

 5 per cent, and depreciation of the machinery at 20 per cent., the compara- 

 tive economy of the different types of machines is shown by the U. S. 

 Department of Agriculture in the graph (Fig. 44). 



0.0002 

 0.0001 



Number of Bottles 



FIG. 44. Curves showing the labor and overhead costs of filling and capping by dif- 

 ferent methods at various-sized plants. 



(Milk Plant Letter No. 41, Dairy Div., U. S. Dept. of Agriculture.) 



The cost of the automatic fillers was taken at 12,500, of the rotaries at 

 $800, of the machine fillers and cappers at $1,200, and that of the fillers 

 where capping was done by hand at $250. Taking the wage at 20 cts. an 

 hour the average labor costs are computed for each type of machine by 

 dividing this amount by the number of bottles filled and capped per man 

 per hour which shows a cost of 0.016 ct. for the automatic machines, 0.025 

 ct. for the rotaries, 0.024 ct. for the machine fillers and cappers and 0.036 

 ct. for the hand capping. Reference to Fig. 44 shows that the curve 

 representing the rotaries intersects the hand-capping curve at 3,400 which 

 indicates that in plants handling less than that number of bottles the 

 hand-capping system would be the more economical. The rotary curve 

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