The Park Governments of Chicago 115 



It should be noted that, while the above classification includes 

 expenses of the motor truck, it does not include expenses of the 

 motor sprinkler, motor grass-cutters, or motorcycles. The item 

 of $2,556 for rental during 1910 was incurred prior to the pur- 

 chase of additional machines in that year. The fact that $1,810 

 was paid during 1910 for the single item of new tires on the 

 three Pierce-Arrow machines is an indication both of the hard 

 wear to which the machines are put and also to the laxity of con- 

 trol over cost of upkeep. The average of $50 per month per car 

 is excessive. 



In arriving at costs of maintenance and operation, the prin- 

 ciple is firmly established in the administration of both public and 

 private business that an annual charge should be included for 

 depreciation, or wear and tear, on plant and equipment. In 

 determining the rate of depreciation on automobiles owned by the 

 South Park Commissioners February 28, 1911, the end of the 

 period reviewed, consideration has been given to their period of 

 service as compared with the average life of automobiles, and also 

 to their physical condition. An endeavor was made to determine 

 the going value, or probable life, of the machines if they were 

 continued in the park service. The rate of one and one-half 

 per cent, per month is believed to be a conservative and fair 

 allowance for depreciation. With respect to machines exchanged 

 during the last five years, the difference between the purchase 

 price and the allowance in exchange has been considered as the 

 amount depreciated. 



The estimated amounts chargeable against automobile service 



for depreciation for the last five years, when added to the 



expenses set forth on the park records, show the total cost of 



automobile service during the last five years to have been as 



follows : 



Expense per 

 Year. Park Records. Depreciation. Total Cost. 



1906 $17,595 $2,876 $20,471 



1907 12,575 3,992 16.567 



1908 11,974 3,764 15.738 



1909 13,787 3,859 17,646 



1910 25,978 4,870 30,848 



Total $81,909 $19,361 $101,270 



