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VII. The Newtonian Constant of Gravitation as Affected by Temperature. 
By P. E. Shaw, B.A., D.Sc. 
Communicated by C. V. Boys, F.R.S. 
Received October 19,—Read December 2, 1915. 
Contents. 
Page 
I. Introduction.349 
II. Indirect experimental evidence.352 
III. Methods employed.354 
IV. Precautions.357 
V. Early experiments.359 
VI. Final experiments.361 
1 General description.361 
2. Support for the vacuum tube.361 
3. Torsion-head system.361 
4. Small mass system.363 
5. Optical arrangement.. 364 
6. Large mass system.366 
7. Various beam systems.366 
8. Sealing materials used ..367 
9. Preparation of apparatus for an experiment.367 
10. Description of experiments.372 
VII. Tests applied.384 
VIII. Conclusion.389 
1. Technical summary and suggestions.389 
2. General summary.390 
I. Intbohuction. 
1. This paper deals with the possible existence of a temperature coefficient in the 
law of gravitation and gives an account of experiments made to discover this 
coefficient. The apparatus used • is of the Cavendish torsion-balance type, and the 
range of temperatures is from 15° C. to 250° C. The result of a prolonged research 
is shown in the summary. 
The accumulation of negative results in the experimental study of gravitation is 
remarkable. In consequence of the indifference of the gravitative force to changes of 
conditions (other than those given by the simple law f — GM m/d 2 ), none of the many 
theories of gravitation so far propounded has received general acceptance for lack of 
.VOL. CCXVI.-A 544. 3 B [Published May 27, 1916. 
