66. Report or DEPARTMENT Of BACTERIOLOGY OF THE 
four cups which are applied to each cow are connected by 
short rubber tubes to the teat cup connector, as shown in 
detail for the Burrell-Lawrence-Kennedy machine (Plate IV, 
fig. 2), and a larger tube conducts the milk from this to the 
pail. Two cows are connected to a single pail. The vacuum 
is furnished by a large pump and its application to the udder 
is made intermittent by a mechanical device, the pulsator 
piston, which is placed at the top of the pail. | 
In using the machine the vacuum is applied to the teats 40 
to 60 times per minute. After each application air is allowed 
to enter the teat cup, the curtain at its upper end relaxes and 
the teat fills with milk. Up to March, 1909, this air was sup- 
plied through relief openings at the end of the teat cup con- 
nectors and through an opening on the pulsator head (Plate 
IV, fig. 2). The machine used after this date had no relief 
openings on the pulsator head. 
During the past two and one-half years the Burrell-Law- 
rence-Kennedy machine has undergone numerous improvements 
at the hands of its makers. It has been necessary to test the 
influence of the more important of these changes so that our 
final results would represent the machines actually upon the 
market. While the milking machine will undoubtedly con- 
tinue to be improved it is believed that the principles of man- 
agement here outlined will continue to apply. 
TECHNIQUE 
A statement of the conditions under which the tests were 
conducted is necessary to a comprehension of the results and 
is here presented. The barn conditions were made to approxi- 
mate as closely as possible those of a good farm dairy and as 
has already been noted the machine was run in accordance with 
the directions of the manufacturers except in so far as it was 
necessary to vary the conditions in testing the individual fac- 
tors. These variations will be noted in connection with the 
experiments where they occurred. 
Stable conditions.— There are approximately 5 sq. ft. of win- 
dow surface and 370 cu. ft. of air space for each cow, addi- 
