( i9 8 ) 
[February 
PROCEEDINGS OF SOCIETIES. 
Royal Society, January g. — The first paper was a “ Note on 
the Inequalities of the Diurnal Range of the Declination Magnet 
as recorded at the Kew Observatory,” by Balfour Stewart, F.R.S., 
and William Dodgson. The authors are at present engaged in 
searching for the natural inequalities of the above range, more 
especially for any of which the period is between 24 and 25 days. 
They have found strong evidence of an inequality of considerable 
magnitude of which the period is 24*00 days, very nearly. They 
have also found preliminary evidence of the existence of two 
considerable inequalities having periods not very far from 24*65 
and 24*80 days. These two appear to come together in about 
eleven years, but the exadt time of this cannot be given. No 
trace of any inequality with a period of 24*25 days has been 
fouud. We shall give a report of a more recent paper on this 
subject in our March number. 
“ Some Experiments on Metallic Reflexion,” by Sir John 
Conroy, Bart., M.A. The author finds that when light is re- 
flected from a polished surface of gold or copper in contadt with 
various media, the angle of principal incidence diminishes, and 
the principal azimuth increases with the increase of the refradtive 
index of the medium in contadt with the metallic surface ; and 
further, the diminution in the value of the principal incidence 
appears to be nearly in proportion to the increase of the refrac- 
tive index of the surrounding medium. The values of these 
angles for gold with red light are — 
Principal Principal 
Incidence. Azimuth. 
In air... 76° o' 35 0 27' 
In water 72 46 36 23 
In carbon bisulphide ... 70 03 36 48 
Assuming that the angle of principal incidence for a metal is the 
same as the angle of polarisation of a transparent substance, 
— that is, the angle whose tangent is equal to the refradtive 
index, — the value of that angle in air, as deduced from the mea- 
surements made in water and carbon bisulphide by multiplying 
the tangent of the principal incidence in those media by their 
refradtive indices, is 76*53 and 77*22 instead of 76. 
“ Researches on the Absorption of the Ultra-Violet Rays of 
the Spedtrum by Organic Substances,” by W. N. Hartley, F.Inst. 
Chem., F.R.S.E., F.C.S., and A. K. Huntingdon, F.Inst. Chem., 
A.R.Sc. Mines, F.C.S. The authors find that — 
