A. 8 Kimball—Journal Friction at Low Speeds, 198 
course of the experiment is obvious. The experimental shaft, 
loaded with a known weight, was driven at different speeds, the 
rewired power noted, and the coefficient of friction calculated. 
he results of seven series of experiments are shown in the 
following table, in which the first column shows the velocity of 
the circumference of the journal in feet per minute, the seven 
following columns giving the correspunding coefficients of fric- 
tion. Since it was found impossible to maintain the same state 
of lubrication for any great length of time, every series which 
could not be completed in one half day was left unfinished. 
Taste I. 
Af a. b C. d. é. Fo g- 
5 is (-° aes 0° WPS 6: Hines 7 SPC) | RT a | 
2°17 “153 150 l 131 129 114 109 
5°15 122 128 122 “080 "080 097 “083 
10°99 “089 086 “069 067 080 060 
Sd ae ot "068 058 “066 052 053 
42°86 “068 “060 "045 "041 
In spite of the irregularities to be seen in this table, the law 
as stated above is clearly shown. Some of the discrepancies 
are doubtless due to variations in the state of lubrication of the 
journals. The pressure on the lower boxes in series a, ¢, d an 
e, was 180 pounds; in series 6, fand g, 210 pounds. Ina, 8, 
c,d and e, the journals were lubricated by wiping them with a 
handful of waste saturated with sperm oil. In / and g, as 
experimental shaft: 
Taste IL 
Speeds, 59’. 217. 616 10°99! 19°71’. 42°86" 
(55 4°3 3°5 2°5 2-0 2-0 
54 4°2 3°6 26 1°9 19 
. 5°38 4°3 3°6 2°5 1°9 1°9 
Differences | 54 44 3°5 2°5 2-1 1-9 
ie PES wuae ers ae 24 19 2-0 
: 5-5 4°3 3°5 2°3 2-0 2-0 
5-4 4°3 3°6 2°5 2-0 2-0 
54 4°3 3°6 2°5 1°9 1°9 
Averages, 5°41 4°28 3:65 2°47 1°96 1-96. 
Coefficients, 187. "148 "122 "086 068 068 
The variation in observations taken at the same some is 
nearly identical in every series with that shown in Table 
Am. Jour, So. —Turep Serres, Vor. XV, No. 87.-- Manon, +78. 
13 
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