

1862.] 103 



There was still slight numbness of the fingers. After the right 

 arm and hand were exercised for a few minutes, the 



Right hand. Left hand. 

 Cent. Cent. 



Temperature between index and median 27'8 



between median and annular .... 26 '8 



At 2 P.M., after walking and using both hands : 



Temperature between index and median 29*8 23 '0 



between the tips of thumb, index, 

 and median 31'2 227 



At 7 P.M. the temperature of both hands was the same. 



II. " On the Rigidity of the Earth." By Professor WILLIAM 

 THOMSON, F.R.S. Received April 14, 1862. 



(Abstract.) 



The author proves that unless the solid substance of the earth be 

 on the whole of extremely rigid material, more rigid for instance 

 than steel, it must yield under the tide-generating influence of sun 

 and moon to such an extent as to very sensibly diminish the actual 

 phenomena of the tides, and of precession and nutation. Results of 

 a mathematical theory of the deformation of elastic spheroids, to be 

 communicated to the Royal Society on an early occasion, are used 

 to illustrate this subject. For instance, it is shown that a homoge- 

 neous incompressible elastic spheroid of the same mass and volume 

 as the earth, would, if of the same rigidity as glass, yield about -J, 

 or if of the same rigidity as steel, about -f of the extent that 

 a perfectly fluid globe of the same density would yield to the 

 lunar and solar tide- generating influence. The actual phenomena 

 of tides (that is, the relative motions of a comparatively light liquid 

 flowing over the outer surface of the solid substance of the earth), 

 and the amounts of precession and nutation, would in the one case be 

 only f , and in the other -f of the amounts which a perfectly rigid 

 spheroid of the same dimensions, the same figure, the same homoge- 

 neous density, would exhibit in the same circumstances.. The close 

 agreement with the results of observation presented by the theory of 

 precession and nutation, always hitherto worked out on the suppo- 



