The Park Governments of Chicago 147 



Sheridan Rd. Mich. Ave. 



Type of Light { Encbsed | ^'lOO^ wa^^^ 



I, Tungsten. 



Mean spherical candle power 200 400 



Watts per post 490 600 



Watts per C. P 2.45 1.5 



Posts per mile 70 144 



Cost of posts erected per mile (with fixtures) $4,515.00 $27,180.00 



Cost of light at %c per K. W. hr per mile per year. . 1,088.01 2,741.04 



Maintenance per mile per year 2,394.00 2,565.60 



Depreciation at 3 per cent and interest on investment 



at 4 per cent. 316.05 1,902.60 



Total cost of lighting per mile per year (including 



interest and depreciation) 3,798.06 7,209.24 



The above figures show that the Hghting of Michigan Avenue 

 has four times the spherical candle power and costs a little less 

 than twice as much as that on Sheridan Road. While the present 

 illumination on Sheridan Road appears adequate for any boule- 

 vard in the city, the additional candle power of the Michigan Ave- 

 nue lamps may be made available at a considerable less cost than 

 that paid by the South Park Board. This may be effected by 

 adopting the Michigan Avenue style of lamps and the Sheridan 

 Road style of posts. The difference between the two kinds of 

 posts used relates to architectural beauty and cost. A recent 

 editorial in a leading daily said : 



"The most graceful and the most durable lamp posts 

 ever erected in Chicago are the concrete posts of Lin- 

 coln Park." 



The posts on Michigan Avenue are of iron. They cost $165 

 each and the Sheridan Road posts only approximately $19. The 

 bronze fixtures on the latter cost $14. If concrete posts and 6-100 

 watt tungsten lamps were used, the cost of the bronze fixtures 

 would be more. Allowing $28 per post for these fixtures and a 

 spacing of 144 units per mile, the cost would be approximately 

 as follows : 



Cost of posts erected per mile (with bronze fixtures) $9,180.00 



Depreciation at 3 per cent, and interest at 4 per cent 642.60 



Maintenance per mile per year 2,565.60 



Cost of current at %c per K. W. hr per mile per year 2,741.04 



Cost of lighting per mile per year (including interest and depre- 

 ciation) 5,949.24 



