266 Prof. Story Maskelyne on the * [Jan. 26, 



example, we find the column a = 56° again to contain values of co-hypo- 

 tenuses approximately equal to the given values ; and therefore have : — 

 Co -hyp. A. 



(I. 6 = 54 19 11 61 23 = Sun's hour-angle. 



| b = 56 18 13 60 47 = Sun's azimuth (N. towards W.). 

 a = 56° i 



| 2. 6 = 55 18 42 61 5 = Sun's hour-angle. 



^ 6 = 57 17 44 60 30 = Sun's azimuth (N. towards W.). 



which give 



o / • o / 



Greenwich apparent time (in arc) 85 30 85 30 



Sun's hour-angle (1) 6123 (2) 61 5 



Diff. = Longitude 24 7 W. 24 25 W. 



Sun's altitude (observed) 18 35 18 35 



Sun's altitudes (auxiliary) (1) 18 13 (2) 17 44 



Diff. = + 22 +51 



Sun's declination from N. A. 19 10 19 10 



Sun's declinations (auxiliary) (1) 19 11 (2) 18 42 



Diff. = 1 +28 

 This example is represented in the third diagram annexed. 



January 26, 1871. 

 General Sir EDWARD SABINE, K.C.B., President, in the Chair. 

 The following communications were read : — 



I. " On the Mineral Constituents of Meteorites." By Nevil Story 

 Maskelyne, M.A., F.R.S., Professor of Mineralogy, Oxford, 

 and Keeper of the Mineral Department, British Museum. Re- 

 ceived November 3, 1870. 



(Abstract.) 



In the memoir now offered to the Society the author gives the results of 

 his investigation of the meteorites of Breitenbach and of Shalka. A 

 preliminary notice of two of the minerals occurring in the former, which 

 is of the Siderolite class, was read before the Society in March, 1869 

 (Proc. R. S. vol. xvii. p. 370). 



After entering upon the probable history of the Breitenbach Siderolite, 

 and endeavouring to identify it with certain other Siderolites that have 

 been found, or have been recorded as found, in the region extending from 



