654 Proceedings of the Royal Society 
la 2 
To obtain the repulsion 
This gives 
dk _ 
dx 
and 
II 
and 
II 
dM 7 r 
kx 
dx a 
1 - k 2 
J(E-F) 
| (2 -£ 2 )E - (2 - 2& 2 )F | . 
By substituting sin 2 y for k 2 this becomes 
— = 2 W cosy { (1 + sec 2 y)E - 2F l • 
ax v ) 
One of the instruments exhibited has two pairs of coils. In it 
a =10 centimetres. 
07=1*048 „ 
.*. & = siny = sin 87°. 
E = 1*005258587 
F= 4*338653976 
cos y = *0523360 
sec y = 19*107323 
let2f 
ax 
9 
= G 
.*. log G= 1.3818437 .*. G= *24090. 
The other instrument has only one pair of coils. In it 
a = 15*3008812 
x— 1 . 
The value of G is calculated in the same way. 
3. On the Pelvic Girdle of Birds and Reptiles. By Professor 
D’Arcy Thomson. 
4. On Sulphines. By Orme Masson, D.Sc. 
