TEST WEIGHT OF GRAIN I ACCURACY OF TESTING APPARATUS. 11 
METHOD OF DETERMINING ACCURACY AND SENSITIVENESS OF 
BEAM. 
Before attempting to cheek the accuracy of the beam the base 
of the tester should be leveled and, if it is of the standard type with 
horizontal arm and trig loop, this level should be tested by examin- 
ing the position of the projection or pointer on the end of the beam 
in its relation to the trig loop. The pointer should be in the center 
of the trig loop both horizontally and vertically when the empty 
kettle is on the beam and the counterpoises are at zero. If this is 
not the case the leveling screws should be adjusted until it is true. 
There are two methods of checking the accuracy of the beam 
graduations. In the more simple and direct method a special set 
of 14 accurate testing weights is used while in the other method an 
ordinarv set of metric weights is used. 
Fig. S. — Special weights used in determining the accuracy of the beam in the weight- 
per-bufchel testing apparatus. In making the test these weights are placed in the test 
kettle. 
The 14 special weights illustrated in figure 8 are marked to repre- 
sent the following number of pounds per bushel : 60. 50. 10. 30. 20, 
10, 5, 2, 2, 1, 0.5. 0.2, and 0.1. Each weight actually weighs & of 
its marked value. To test the beam place any weight or combina- 
tion of weights, within the range of the beam graduations, in the 
kettle and bring the beam to balance by means of the counterpoise. 
The combined readings of the counterpoises should now equal the 
combined represented weights in the kettle, and the difference be- 
tween the weight represented in the kettle and on the beams, if any. 
is the error of the beam. 
It is equally essential in making correct weight-per-bushel tests, 
especially on " line " samples, that the beam should not only indicate 
an apparently correct reading when a given weight is placed in the 
test kettle but that it should also be sensitive to within one-tenth 
of a pound per bushel. That is, the beam should be sufficiently sen- 
sitive to move either up or down noticeably, and in the case of a 
