LOGGING IX THE DOUGLAS FIE REGION. 
167 
SPARK ARRESTEES, WATER. TANKS, SLEDS. 
The selling prices of spark arresters are given under the heading 
" Ground yarding." Steel tanks adapted for use in connection with 
loading engines cost about $100. Loading 
engine sleds cost about $200 and last from 
three to four years. Spark arresters, water 
tanks, and sleds are discussed under the 
heading " Ground yarding." 
OIL-BURNER EQUIPMENT. 
The approximate cost of the equipment 
used in burning crude oil on loading engines 
amounts to $375. This price includes the 
tank on the rear end of the sled, which is 
used for the storage of both oil and water. 
The cost of the maintenance of this equip- 
ment amounts to about $25 per year. 
Fig. 68. — Loading- block. 
BLOCKS. 
Only such blocks as are used in loading are taken up here. Some 
of the blocks listed under this heading, however, are used in over- 
head and high-lead yarding. 
Figures 68 and 69 show two of the types 
of loading blocks. Several other types 
are used. The proper size of blocks was 
discussed in a general way under the 
heading " Ground yarding." The size to 
be used with different methods of load- 
ing is suggested in the discussion headed 
" Methods." 
The cost of loading blocks varies be- 
cause of difference in the type, size, and 
make, and because different materials are 
used in their construction. The following 
gives the weight, size, and selling price 
of two types of loading blocks, f. o. b. 
Portland in March, 1916. It should be 
borne in mind that blocks are manufac- 
tured by several companies and that they 
can no doubt be purchased as satisfactorily at Tacoma, Seattle, and 
other points as at Portland. 
Fig. 69. — Overhead block. 
No. 1 sheaves, 12 by li inch manganese steel. 
No. 2 sheaves, 14 by li inch manganese steel. 
Net price. 
$18 
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