234 PROFESSOR E. G. COKER ON 
comparative readings were required. The thermometer bulbs I were inserted in the 
main tubes, and secured by flexible rubber joints J,* as indicated. 
In carrying out a test the centrifugal pump was first set in operation, and when — 
the readings of the extensometer became steady, the gas flame was applied to the - 
extension barrel of the pump, and the readings were taken, at intervals, of the 
PCT 
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temperature and the extension, until a temperature of about 180° Fahr. was reached — 
A new experiment was then begun with a different loading. The testing machine used — 
was not sufficiently powerful to overstrain the tubes used, as these latter were 
exceptionally hard, owing to their manner of production; and for the experiments 
with a permanent overstrain the tubes were taken out and stressed in a Riehle 
testing machine of 60,000 pounds capacity. 
The results of the tests on the brass tube are shown in Table I., from which it will 
* “On a flexible Joint for securing Thermometer and like Stems and Tubes,” E. G. Coxmr, Physical Review, 1903. 
