78 General Monthly Meeting. [April 10, 



a favourable light, became conspicuous after treatment with acid. 

 Perhaps the simplest way of regarding the matter is to consider the 

 case of a furrow with perpendicular sides and a flat bottom. If the 

 acid may be supj)osed to eat in equally in all directions, the effect will be 

 to broaden the furrow, while the depth remains unaltered. It is 

 possible that this method might be employed with advantage to 

 intensify (if a photographic term may be permitted) gratings ruled 

 upon glass for the formation of spectra. 



GENERAL MONTHLY MEETING, 



Monday, April 10, 1893. 



Sir James Crichton-Browne, M.D. LL.D. F.K.S. Treasurer and 

 Vice-President, in the Chair. 



W. H. Broadbent, M.D. 



Henry C. J. Bunbury, Esq. 



William Flockhart, Esq. 



Francis Gaskell, Esq. 



George W. Hemming, Esq. Q.CL 



Colin Charles Hood, Esq. 



Charles Langdon-Davies, Esq, 



B. W. Levy, Esq. 



Mrs. W. Eathbone, 



Granville E. Eyder, Esq. 



Mrs. Sharpe, 



F. W. Watkin, Esq. M.A. F.E.A.S, 



were elected Members of the Eoyal Institution. 



The special thanks of the Members were returned for the following 

 Donation to the Fund for the Promotion of Experimental Eesearch 

 at low temperatures : — 



Alexander Siemens, Esq £21 



The Presents received since the last Meeting were laid on the 

 table, and the thanks of the Members returned for the same, viz. : — 



FROM 



Tlie Secretary of State for India — Archaeological Surrey of India, New Series, 

 Vol. I. 4to. 1889. 

 Keport on Public Instruction in Bengal, 1891-2. fol. 1892. 

 The Lords of the Admiralty— Nautical Almanac Circular, No. 14. 8vo. 1893. 



