92 + BULLETIN 875, U. S. DEPARTMENT OF AGRICULTURE. 
with its distributor and which could be sold at a more reasonable 
price. The only answer to this problem which has been developed SO 
far is the wheel-traction or cart type of duster. 
WHEEL-TRACTION OR CART DUSTERS. 
For the wheel-traction duster a hght two-wheel cart is utilized and 
the power for driving the fan, feeder, etc., is derived from the wheels 
of the cart. This duster is pulled by two mules and is operated by 
one man instead of two. By the beginning of 1919 a tentative model 
had been produced which was placed in the field and operated on a 
practical basis throughout that season. This machine proved emi- 
nently satisfactory in spite of the fact that it was very crudely con- 
structed, and it was selected as the most desirable type for general 
use in cotton dusting on a large scale. As built, it proved far simpler 
and easier to operate than the power machines and was especially 
valuable for its convenience in driving through the field. A number 
of duster manufacturers became interested in this type of machine 
and several models based somewhat on this idea are now on the 
market and others are in the course of construction. These differ 
widely and embrace the ideas of individual designers, but the general 
principles of construction are more or less the same. Practically all 
of the machines are built with an arched axle providing a 42-inch 
clearance beneath the arch and having a tread of about 48 inches, 
thus enabling satisfactory operation in any cotton rows not narrower 
than about 36 inches. 
Tt has been found that under normal conditions one of these 
wheel-traction machines will probably average about 25 acres per 
night of operation. It may exceed this amount under very favorable 
conditions but it is not safe to figure on a greater average than this. 
As has been pointed out, it is undoubtedly desirable to provide 
equipment for treatment at a time interval of about 4 days. Owing 
to rains and other interruptions, it is undoubtedly not safe to figure 
on more than three days’ operation out of the four. Consequently, 
about the best that can be expected of one of these machines is that it 
will handle in the neighborhood of 75 acres of infested cotton 
throughout the season. 
So far the machines of this type which have been built have been 
placed on the market at a rather high price, ranging from about 
$350 to $500. The manufacturers have taken extreme precautions 
to place the highest quality of workmanship and material in the con- 
struction and this has resulted in making the price of the mazhine 
higher than is generally desirable. It still remains to be seen 
whether or not this cost is justified by increased efficiency of the 
machines. It seems quite probable that other machines built on 
