LOGGING IN" THE DOUGLAS FIR REGION. 



167 



SPARK AERESTEES, 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-BTTENEE 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. 



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, arid 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. 



Net price. 



No. 1 sheaves, 12 by 1| inch manganese steel_ $18 



No. 2 sheaves, 14 by li inch manganese steel 22 



Fig. 69. — Overhead block. 



