378 
DR. P. E. SHAW ON THE NEWTONIAN CONSTANT OF 
Table II (continued). 
Position. 
T. 
T.R. 
R. 
Ampli¬ 
tude. 
Z. 
Range. 
Mean 
range. 
A, 
At- 
Start Heat at 11.5. Stop Heat at 1.5. 
°C. 
A 
2.5 
343 • 0 
46-8 
257-0 
210-2 
141-8 
172-3 
180 
115-2 
172-3 
210-7 
yo ■ o 
(172-0) 
201-2 
B 
343-2 
480-8 
302-0 
178-8 
120-0 
81-0 
373-8 
173 
422-0 
373-6 
201-2 
341-0 
(373-2) 
~ 
201-2 
A 
2-27 
342-95 
51-2 
253-7 
117-5 
202-5 
136-2 
91-5 
172-3 
172-2 
166 
209-0 
(172-0) 
°C. 
13-1 
Headings in columns 3, 4, 5, 6, 7, 8 are in millimetres. 
fifth column shows the amplitude of swing. The next column has the rest position 
(Z) calculated from the formulae 
z = e _ t- 6 ) 2 _ =J+ _ 0* _ 
( a — b ) + (c — b) (c — 6) + ( c—d ) 
where a, b , c, d, are the readings in order in column 4. These formulae are based 
on the supposition that damping is so small that the successive amplitudes may be 
considered to be in geometric progression. The numbers in brackets in column 6 
denote the mean value of Z corrected for the change, if any, in the reading of the 
reference mirror. The seventh column shows the range, i.e., the corrected scale 
reading when passing from A to B position or vice versa. The eighth column has 
the temperature of the lead spheres as given by mercury thermometers. The last 
column shows the temperature of the outside of the vacuum tube below the window, 
as given by a platinum thermometer. The change in temperature varies up and down 
without much connection with the temperature of masses, M, M. Likewise the 
change of temperature in the water leaving the water-jacket amounts to 0'25° C., 
due mostly to change in temperature of the tap water. These small changes some¬ 
times up, sometimes down, cannot influence the general result. As a rule the water 
temperature is very steady for long periods. After a set of readings at low 
temperature, the thermometers are removed from the lead spheres and the nichrome 
