Vol.. 8, 1922 
PHYSICS: C. BARUS 
313 
wXc equally constant, and so, if we takenoc T^-^ (see (19)), we have Xoc T'"^, 
approximately. 
24. In the attempt, not hopeless, which I have been making of late to 
explain the various "transverse" effects in accordance with the proposi- 
tions of my Summary y I have been led to the conclusion that the diameter 
of the outer electron shell of an atom may be as small as one-half the 
means centre to centre distance of neighboring atoms. This conception 
makes it comparatively easy to accept the proposition that X may be, 
as already indicated in (21), fifty ^ times as great as this centre to centre 
distance. 
If X really extends through many one- atom- thick layers of the metal, 
a slight decrease in the probability of an electron's passing through any 
single layer would be enough to account for the rapid decrease in X with 
use of temperature, as found in (23) . 
1 "A Possible Function of the Ions in the Electric Conduction of Metals," Proc. NaT. 
Acad. Sci., Vol. 3, March 1917. 
2 Journal de Physique, series 4, vol. 4, pp. 690-692. 
^ See pp. 86-88 of his Molecular Constitution of Matter. 
^ Borelius makes a like assumption regarding the kinetic energy of what he calls free 
electrons. See Ann. Phys. Chem., vol. 57, p. 233. 
^ In the paper referred to in footnote (1), I held quite the opposite opinion, making 
the effect of the field at this juncture the basis of my explanation of Ohm's law. 
^ If this conception is sound, it would not be surprising to find very great pressure 
unfavorable to the state of superconductivity. 
^ For a Summary see Proc. NaT. Acad. Sci., 7, No. 3, March 1921. 
^ Bridgman has of late taken X to be "many" times the atomic diameter. 
STATIC DEFLECTION, LOGARITHMIC DECREMENT AND 
FIRST SEMI-PERIOD OF THE VACUUM GRAVITATION 
NEEDLE'' 
By Carl Barus 
Department of Physics, Brown University 
Communicated, August 12, 1922 
1. Apparatus. — The object of the present experiments is a completion 
of the work of an earlier paper, ^ by carrying the exhaustion of the case as 
far as practicable. 
In spite of the care taken to seal all parts of the extended apparatus, there 
remained a constant leak of .0035 mm. of mercury per hour, the seat of 
which I was unable to detect; but as experiments with gradually de- 
creasing vacua were primarily contemplated, this leak was here no serious 
