350 
DR. P. E. SHAW ON THE NEWTONIAN CONSTANT OF 
data wherewith to test them. Some recent theories, which consider the possibility 
of temperature effect, are :— 
N. Morozov* advances a wave theory on which the attraction of masses would 
vary with temperature. 
G. Mie,| a theory of matter which includes among its corollaries a temperature 
coefficient of l/lO 13 per 1° C. to the “ so-called Newtonian constant.” 
N. Bohr, | in a paper on the constitution of the atom, assumes that gravitation 
like radio-activity is unaffected by all physical and chemical agencies, and hence the 
writer ascribes both these properties of the atom to its nucleus; whereas other 
physical properties are due to the electrons in the outer regions of the atom. But it 
should be noted that, at least as regards temperature, the data for gravitation are 
deficient. It is not easy to conduct experiments on a short range of one or two 
hundred degrees (see later) which is a small portion of the thousands of degrees of 
known measured temperatures. So it is necessary to speak with diffidence on this 
special branch of the subject of the constitution of the atom. 
2. Determinations of the Newtonian constant have hitherto been made at ordinary 
temperatures only, special care being taken to maintain uniformity in temperature 
throughout the apparatus used ; otherwise convection in the air or strains in the 
movable system might produce grave errors. This is shown repeatedly in the well- 
known researches by Prof. C. V. Boys§ and Prof. J. H. Poynting.|| The necessity of 
providing a steady temperature about the delicate parts of the apparatus has hitherto 
been considered an insuperable bar to any direct experiment to discover a temperature 
effect for G. In fact, in 1905, shortly before the present research began, the late 
Prof. Poynting and Mr. P. Phillips^ wrote as follows.:—The difficulties of exact 
determination (of the Newtonian constant) at ordinary temperatures are not yet 
overcome and at very high or low temperatures they would be so much increased 
that the research seems at present hopeless.” 
3. Yet indirect investigations have been made. Poynting and Phillips** counter¬ 
poised a mass of 208 gr. on a balance and varied its temperature between 100° C. 
and —186° C. They came to the conclusion that the resulting change in weight, 
if any, is less than l/lO 9 for 1° C. for the range 100° C. to 0° C. and l/lO 10 for 1° C., 
for the range 0° C. to —186° C. 
Another balance experiment on change in weight with temperature by Southerns ft 
led to a somewhat similar result. 
* ‘ Jurn. Russik Chimicisk Obscestva,’ 40, 2, pp. 23 to 35, 1908. 
t ‘Ann. der Pkys.,’ 1913, No. 1. 
J c Phil. Mag.,’ July 26, 1913. 
§ ‘ Phil. Trans.,’ 1895. 
|| ‘Phil. Trans.,’1891. 
U See ‘ Roy. Soc. Proc.,’ A, vol. 76, p. 445, 1905. 
** Loc . cit . 
ft ‘ Roy. Soc. Proc.,’ A, vol. 78, 1906. 
