186 
Proceedings of the Royal Soeiety 
+ i| sin (/3-a) (-j) sin 2 (^-a)+ 
Also 
log {a + b} = log F/'a^ + + 2a& cos (p - a))^ tan"^ « sin a + 6 sin ^ "1 
® *■ ^ LV V /y a cos a + & cos /8J 
1, ^ a sin a + h sin B 
= log (a^ + b^ + 2ah cos (B - a)) + 1 log tan"^ = ^ 
2 V ® acosa + 6cos)S 
Equate tbe components along the initial axis, and put p -a = 0 . 
The direct logical power of the method is illustrated by the mode 
in which it deduces the expressions for the acceleration along and 
perpendicular to the radius vector for a point moving in any plane 
curve from the expression for the velocity ; 
T = r .6 
Given 
die 
^ = dr.0-h irdO . 9 , 
then apply that principle again, 
d^T 
-p - dh' . 0 + idrde . 6 + idrdO . 0 + irdW . 0 + ihxie ‘^ . 6 
— (d'^r - r{d6Y ) . 0 + i{fdrd9 + rdd^B ) . 6 . 
5. Od Heat-Conduction in Heterogeneous Bodies, as modified 
by the Peltier and Thomson effects. By Professor Tait. 
6. Hote on the Thermo-electric Position of Pure Ptuthenium. 
By Professor Tait. 
Monday, ^th May 1883. 
Peofessoe DOUGLAS MACLAGAH, M.D., Vice-President, 
in the Chair. 
At the request of the Council, Professor Geikie delivered an 
Address on Recent Advances in European Pleistocene Geology. 
BUSINESS. 
The following Candidates were balloted for and declared duly 
elected Fellows of the Society : — Professor Butcher; Mr G. 
M‘Roberts, E.C.S.; Mr R. W. Eelkin, E.R.G.S.; and Mr G. Leslie, 
M.B., C.M. 
