THE MEASUKEMENT OF RAIN. 7 



50^ inches and 62^'^ inches — the latter being at an elevation 

 of about 1750 feet, and the former 700 feet above the sea. 



It seems exceedingly probable, from an examination of 

 this new gauge, that it is liable to be affected in a serious 

 degree by evaporation, and the difference may perhaps be 

 assigned to this cause. The whole apparatus is placed above 

 the surface of the ground — the water is received by a metal 

 funnel, and conducted from thence by a short pipe at the 

 bottom, through the top of a wooden box, to a glass bottle 

 of large area placed within the box and open at the top. 

 The water is not covered by a float, and the surface is there- 

 fore in contact with the atmospheric air. It is not suggested 

 that the evaporation would be as great as from the surface 

 of an open pond; but that it does take place to a consider- 

 able degree seems to be evident. 



As evaporation is greater in proportion to the altitude of 

 the situation, the supposition that the discrepancy is to be 

 assigned to this cause, will also account for the anomaly (as 

 compared with the general result of all the other returns), 

 at Todd's Brook and Comb's Moss, where it would appear, 

 from the results furnished by these new gauges, that less 

 rain falls on high land than on low. If the returns were 

 properly corrected by a due allowance for evaporation 

 according to the altitude, the true state of the case would 

 probably be found to agree with the evidence from other 

 places. 



The rain gauge at the top of the inclined plane at (^hapel- 

 le-Frith is an exception to this rule, as it appears to show, 

 pretty regularly, less rain than falls at Comb's Reservoir at a 

 lower elevation. This may probably arise from local causes, 

 as it is at variance with the general testimony within the 

 range of the same elevation. 



All the Society's gauges, — those at Fairfield, and that at 

 the top of the inclined plane at Chapel-le-Frith, put down 

 by the Canal Company, — are cylindrical gauges, with an 



