Meteorological Society. 385 



eclipses of the sun. ithly, By occultations of the fixed stars. 

 And 5thly, By meridionial transits of the moon. The first 

 three of these, by reason of their infrequency and obvious 

 sources of inaccuracy, are of very limited utility ; while the 

 fourth method is rendered uncertain from its involving a 

 doubtful datum, the compression of the earth, as well as other 

 difficulties which the author pointed out. He then proceeded 

 to point out that the fifth method was greatly superior to any 

 of the others, in which opinion he was supported by the tes- 

 timony of Dr. Maskelyne, Bernoulli, and many eminent 

 astronomers who were quoted. Notwithstanding its high re- 

 commendations, this method has not been successfully adopted 

 in practice, and has even led to some awkward anomalies, on 

 account of its having been customary to take the moon's 

 centre reduced to the meridian, and to compare it with the 

 apparent places of stars passing the meridian about the same 

 time in any parallel of declination. 



The newly proposed method consists in merely observing 

 with a transit instrument, the differences of right ascension 

 between the border of the moon, and certain fixed stars pre- 

 viously agreed upon, restricting the observations to stick stars 

 as differ very little in declination from the moon, and denomi- 

 nated moon culminating stars. The attention of astronomers 

 has been called to this method by M. Nicolai, of Manheim, 

 in several numbers of Schumacher's Nachrichten. It is quite 

 independent of the errors of the Lunar Tables (except so far 

 as the moon's horary motion in JR is concerned). It does not 

 involve the quantity of the earth's compression. It does not 

 require a correct knowledge of the position of the star ob- 

 served, nor does an error of a few seconds in the clock sen- 

 sibly affect the result. Hence much trouble is avoided, many 

 causes of error precluded ; besides all which, the method is 

 universal. 



METEOROLOGICAL SOCIETY. 



March 10.— The reading of Dr. T. Forster's " Memoir on 

 the Variations of the Reflective, Refractive, and Dispersive 

 Powers of the Atmosphere" was resumed and concluded. 



This memoir relates to certain branches of the subject ol 

 atmospheric refraction, belonging to the province of Meteoro- 

 logy which Dr. Forster states to have been particularly neg- 

 lected : these are, the variations in the refractive, dispersive, 

 and reflective powers of the atmosphere, resulting from the 

 diffusion therein of different modifications of cloud, which 

 are themselves affected by local cir ^stances, and which 

 vary greatly at different times; and the effects of hat varia- 

 tion on the colour of the light transmitted by the planets and 



