18 BULLETIN 627, U. S. DEPARTMENT OF AGRICULTURE. 
From Table VIII it will be seen that the cost of heading and stack- 
ing an acre of wheat varies from $1.06 to $1.38, according to the size 
of the crew. The cost per bushel will, of course, depend upon the 
yield. In the last two columns are shown the approximate cost per 
bushel based on yields of 16 and 30 bushels per acre. The cost 
per day with the small crews has been divided by 16, and the cost 
per day with the large crews has been divided by 30, in order to ap- 
proximate actual conditions, since the larger crews are used more 
often where the yields are heaviest. From these columns it will be 
seen that the cost per bushel ranges from 44 to 7 cents. The cost of 
cutting an acre of wheat with a header and stacking the heads is very 
little greater than the cost of cutting when the work is done with a 
binder. It will be seen, therefore, that there is generally a saving 
in harvesting with a header when the cost of shocking and stacking, 
or hauling to the separator, is considered. 
COMBINES. 
By far the cheapest method of harvesting and thrashing wheat 
practiced in this country at present is by means of the combined 
harvester, a machine that cuts the heads from the wheat and thrashes 
them at the same operation. Unfortunately the use of this outfit 
has been limited to certain sections where the grain ripens on the 
stalkay (PIT, fig; 1.) | 
“ Combines,” as they are commonly called in the sections where 
they are used, vary considerably in size and weight, according to 
the type and make. The early forms of combines were just what the 
name implies, i. e., a combination of two machines, a header and a 
separator, so arranged that the header delivered the cut heads di- 
rectly to the thrashing cylinder. The first outfits were drawn by 
horses, and both the header and separator mechanisms were operated | 
by “bull” or drive wheels. <A little later steam was utilized_to. oper- 
ate some combines, and still later gasoline engines, either in the 
form of tractors or mounted on the combines themselves as single 
units, were used. At present most combines are still drawn by 
horses, although auxiliary gasoline engines frequently are used to 
operate the mechanism, the horses merely moving the outfit. 
The combine, like most other harvesting machinery, has undergone 
considerable improvement during the last few years, and instead of 
being merely a combination of two machines primarily designed for 
two different kinds of work, the combines of to-day are designed and 
built for the complete operation of cutting and thrashing the grain. 
The width of swath cut by combines varies from about 7 to 25 feet. 
The first combines were used principally on very large areas of 
wheat, and were of necessity of large size, in order to complete the 
work during the weather suitable for harvest. They required about 
_s 
