Manchester Memoirs, Vol. lix. (191 5), No. l£. 35 



Electricity. 

 Sheets 59 and 60 



No. 59 is a small diagram (3" x 23") illustrating Davy's 

 explanation of electrolysis. It shows 6 "atoms " of water, 

 the oxygen being indicated by O and the hydrogen by 0. 

 The upper part of the diagram shows the position of the 

 atoms when not connected with a battery, and the lower 

 part shows the liberation of the gases at the electrodes 

 when the current passes. This diagram is probably taken 

 from a paper on " Theories of the Excitement of Galvanic 

 Electricity" by William Henry (see Memoirs, 2, p. 311, 

 1813). No. 60 is a larger diagram (2i"xi/") like 59 

 without showing any electrodes. 



Meteorology. 



Sheets 61, 62, 63 and 64. 



These relate to the Theory of Rain, which Dalton 

 adopted and extended, 11 that was first given by Hutton. 12 

 The latter had pointed out that the quantity of vapour 

 capable of entering the air increases at a greater rate 

 than the temperature. Hence it may be concluded that 

 when two volumes of air at different temperatures are 

 mixed together, each being previously saturated, a pre- 

 cipitation must ensue, in consequence of the mean 

 temperature not being able to support the mean quantity 

 of vapour. 



No. 61 (21" x if) is headed "Theory of Rain," 

 and shows a curve plotted connecting the pressure 

 of saturated water vapour and its temperature. Dalton 

 has written on the diagram the numbers used : — 



11 See Dalton's observations on ihe barometer, thermometer, and rain at 

 Manchester, from 1794 to 1813 inclusive. Memoirs (2nd Scries), 3, p. 483, 

 1819. 



12 "The Theory of Rain," by J. Hutton. Trans. Roy. So:. Edin. x 

 Vol. I., p. 41, 1788; Vol. II., p. 39, 1790. 



