296 Ituj/al Institution. 



"The cusps were generally sharp, but were tuice sensibly blunted, 

 owing to irregularities in the lunar disc, independent of which their 

 varying in direction was easily observable. There was no scattered 

 light. Tiie macula occulted was the only spot on the solar disc ; and 

 it disappeared in the largest valley on the edge of the moon, near the 

 profile of a conical lunar mountain." 



The morning was remarkably clear, with a light air from S.S.W. 



In a postscript, Capt. Smyth observes : " In the paper by the 

 Rev. W. R. Dawes, * On the Adoption of a Standard of Optical Power 

 by Observers,' (Lond. and Edinb. Phil. Mag. vol. hi. p. 291,) he has 

 supposed that the emersions of Jupiter's satellites, which are inserted 

 in the fourth volume of the Memoirs of the Astronomical Society, 

 were observed by me with the large refractor, and reasons upon that 

 assumption as a fact. In order that the conclusions may not be drawn 

 from wrong premises, I beg to say that the observations which he cites 

 were made with a five-feet achromatic, as stated in the letter sent with 

 them, and therefore probably under an illuminating power very simi- 

 lar to that used at Ormskirk. Still, the acuteness of vision which 

 Mr. Dawes possesses, as has been shown in several difficult trials, 

 forms a substantial part of the argument, for equalizing optical powers." 



IV. Observations on the Method of calculating a Lunar Eclipse, 

 with reference to that of December 26, 1833. By J. Freeman, Esq. 



V. A portion of a paper was read, on the Construction of Astrono- 

 mical Instruments. By F. R. Hassler, Esq., Associate of the Society. 



FRIDAY-EVENING PROCEEDINGS AT THE ROYAL INSTITUTION 

 OF GREAT BRITAIN. 



January 24. — Mr. Faraday on the power of platina and other solid 

 substances to determine the combination of gaseous bodies. — This was 

 an experimental illustration of the sixth series of the author's Re- 

 searches, an abstract of which is given at p. 29 1 of the present Number. 



January 31. — Dr. Ritchie. Further developments in electro-mag- 

 netism and magneto-electricity. — This subject also formed a commu- 

 nication to the Royal Society, and has been reported upon in its place 

 in our Journal. 



February 7. — Mr. Denton the effect of temperature on the balance- 

 spring of time-keepers, and the means of compensating the errors. — 

 Mr. Dent makes both his balance-wheel and spring of glass, and finds 

 very great improvements in the going of the chronometer to result. 

 These seem to be mainly attributable to the perfect elasticity of glass, 

 and the comparatively imperfect elasticity of the malleable metals 

 which have hitherto been used for these springs. The investigation, 

 which is very laborious, is still in progress. 



February 14. — Mr. Faraday on the principle and action of Erics- 

 son's caloric engine. — The inventor of this engine has applied the ex- 

 pansion of hot air to produce an available motive power. A five- 

 norse-power engine has been constructed, and appears to work well. 

 A much larger engine is in progress, which will admit of the applica- 

 tion of every test of its utility and advantage. 



February 21.— Dr. Grant on the development of the nervous 



