1876.] 



Report of the Meteorological Committee. 



189 



do me the favour of bringing this communication to the notice of the 

 Society ; and I need not say that I shall be exceedingly glad of any sug- 

 gestions for improving the method and utilizing it in making systematic 

 observations of any points which may be elucidated by its means. 



Received December 6, 1875. 



Surveyor- General's Office, 



Calcutta, November 12, 1875. 

 Dear Sir, — In continuation of my letter of last week I enclose a 

 sketch of the lines in the extreme red rays, as nearly as I can make 

 them out, from one of the photographs I have taken in the manner 

 described, and the only one in which I have obtained the lines so clearly. 

 It was taken at 1.48 p.m. on the 8th October (just at the close of our 

 rainy season) with an exposure of 15 minutes, the same arrangement of 

 spectroscope being used as for taking the two negatives I sent you last 

 mail. 



AaBC 



E& 



J? 



HH' 



I have since writing made a successful experiment in obtaining re- 

 versed negatives on insolated, blue-stained, dry bromized collodion plates 

 by means of the reversing action of the red rays passing through ruby 

 glass, and also on similar plates prepared with bromized collodion 

 coloured a bright yellow with tincture of annatto. I have also reason to 

 believe that it will not be impossible to obtain the same reversing action 

 through blue glass ; but further trials are requisite. 



I may also add that I have found that dry bromide plates prepared 

 with the collodion containing annatto are more highly sensitive to the 

 whole spectrum than any others ; so that I have obtained the C, B, a, 

 and A lines quite distinctly on such plates unreversed, and also one line 

 below A at about the same distance from it as a. 



III. " Report of the Meteorological Committee to the President 

 and Council of the Royal Society on the Work done in the 

 Meteorological Office since their appointment in 1866 to 

 December 31, 1875." 



The business of the Office will be reviewed under the three heads into 

 which it is subdivided, and which are as follows : — 

 I. Ocean Meteorology. 

 II. "Weather Telegraphy. 

 III. Land Meteorology of the British Islands. 



I. Ocean Meteorology. 

 The most important task of the Committee at its first institution was 



