464 General Monthly Meeting, [Feb. 1, 



these, retaining its polish. The molecular change is extremely 

 delicate, and can only be seen in certain inclinations to the light ; 

 it does not seem to affect the performance of the glass. Dollond 

 died in 1761 ; but whether made by him or his son, the instrument 

 bears internal evidence of being very old ; and was represented as 

 having been 40 years in the shop where it was bought. We have 

 therefore an experiment of very long duration, and which presents 

 these remarkable points : 1st, There is a notable distance between 

 the radiating surfaces. 2ndly, The impression is permanently 

 etched, and not capable of being removed by any cleaning of the 

 surface. It would be out of place in this note to enter on the 

 theory of this effect. 



[W. R. G.] 



GENERAL MONTHLY MEETING, 



Monday, February 1. 



William Pole, Esq. M.A. F.R.S. Treasurer and Vice-President, 

 in the Chair. 



Richard Corbet, Esq. 



Roger Fenton, Esq. 



Mervyn Hamilton, Esq. 



William Augustus Hillman, Esq. F.R.C.S. and 



John Leighton, jun. Esq. F.S.A. 



were duly elected Members of the Royal Institution. 



Charles Brooke, Esq. F.R.S. 

 was admitted a Member of the Royal Institution. 



The following Presents were announced, and the thanks of the 

 Members returned for the same : — 



From — 



^cfuones, /w5<i</i<e o/"— Assurance Magazine. No. 30. 8vo. 1857. 

 ^no«ywio?fs— Neufchatel, and its Events since 1814. 8vo. 1857. 

 Asiatic Societt/ of Bengal— Jonmal, "No. 263. 8vo. 1857. 

 Astronomical Society, lioi/al — Monthly Notice, Dec. 1857. 



Basel Naturforschende Gesellschqfl—Verhdindlwageii, Viertes Heft. 8vo. 1857. 

 Bell, Jacob, Esq. ilif.^./.— Phannaceutical Journal for Jan. 1858. 8vo. 

 Boosey, Messrs. {the Publishers)— The Musical World for Jan. 1858. 4to. 

 Bombay Geographical &ae<?^— Transactions, Vol. XIII. 8vo. 1857. 



