1892.] of a Conductor when transmitting a Current. 23 



would probably hold good in any case, where a is a coefficient 

 dependent upon the nature of the surroundings, and thus it would 

 only be necessary to determine the resistance of any coil with two 

 different e.m.F.'s to find the value of a and hence the limiting 

 value of the resistance when C —0. 



This is, of course, a mere suggestion and would require a 

 large number of experiments to vei-ify its truth, especially where, 

 as in standard coils, the wire is almost thermally insulated by 

 being embedded in thick layers of paraffin wax, whilst in our 

 calorimeter coil the thermal conduction was very good, the coil 

 being immersed in well-stirred water. The stirrer revolving at 

 the rate of 2000 revolutions per minute. 



We hope to carry out these experiments replacing the calori- 

 meter coil BC, by some paraffin-embedded coil, the Clark cell 

 circuit by a high resistance shunt which would not be appreciably 

 heated by the currents used and would give the means of ad- 

 justing the bridge ; the large German-silver coils BD could be 

 replaced by a Manganin coil with zero Temperature Coefficient of 

 the same resistance as BC, and the arms AC, AD by two equal 

 and similar coils so chosen as to give maximum sensitiveness 

 to the bridge : a tangent galvanometer in the battery circuit 

 ought to give the current-strength to the required accuracy. 



(2) On the Stability of Maclaurins Liquid Spheroid. By 

 A. B. Basset, M.A., F.R.S., Trinity College. 



1. One of the most obscure passages in Thomson and Tait's 

 Natural Philosophy is the one which relates to the stability of 

 Maclaurin's liquid spheroid. The authors state, without proof, 

 that the spheroid becomes unstable when its excentricity exceeds 

 that of the limiting Jacobian ellipsoid which coalesces with it ; 

 that is when its excentricity exceeds •8127. No allusion is made 

 to the fact that Riemann proved many years previously that for 

 an ellipsoidal displacement, the spheroid, if composed oi frictionless 

 liquid, does not become unstable until its excentricity is equal to 

 •9529 ; and as Riemann's result is certainly correct, the natural 

 inference is that the authors were unacquainted with his paper, 

 or were contemplating a disturbance of a more general character. 

 It appears, however, from the papers of Mr Bryan*, that Riemann's 

 result gives the limiting excentricity for which the spheroid is 

 stable, when the disturbance is of the most general possible 

 character ; the statement is therefore misleading, and if Mr Bryan's 

 result is correct, it is in its present form inaccurate. 



But it would seem from certain recent investigations, that the 

 passage may refer to a spheroid composed of viscous liquid. There 

 * Fhil. Trans. 1889, p. 187; Froc. Roy. Soc, vol. xlvii. p. 367. 



