274 MR. G. V. VERNON ON THE MEAN 



and as there were 150 drops, the sum total reaches the 

 startling number of 37 J millions; and these, exclusive of 

 other substances, were collected from 2495 litres of the 

 air of this city^ — a quantity which would be respired in 

 about 10 hours by a man of ordinary size when actively 

 employed. I have to add that there was a marked absence 

 of particles of carbon amongst the collected matter. 



XXII. On the Mean Monthly Temperature at Old Tr afford, 

 Manchester, 1861 to 1868, and also the Mean for the 

 Twenty Years 1849 ^^ 1868. By Gr. V. Vernon, 

 F.R.A.S., F.M.S. 



Read before the Physical and Mathematical Section, December yth, 1869. 



In Vol. I., 3rd Series, of the Memoirs of the Society, in a 

 paper " On the Irregular Oscillations of the Barometer at 

 Manchester,^' I gave reductions of the mean monthly tem- 

 peratures observed by myself for 1849 ^^ i860, and in the 

 present communication I have given the values for the 

 succeeding years down to the end of 1868, completing a 

 period of 20 years. It is scarcely necessary to remark 

 that these values have all been carefully reduced to the 

 Greenwich standard, and corrected by means of the Tables 

 of Diurnal Range, computed and published by Mr. 

 Glaisher. 



As will be seen by the notes appended to Table I., I 

 have been indebted for a few months' observations to Mr. 

 Mackereth^s observations, made at Eccles, and which closely 

 represent those made at Old Trafford. 



* Behind Dr. Angus Smith's laboratory. 



