284 REPORT — 1866. 



The observations were submitted for discussion to Mr, Baxendell, F.R.A.S., 

 who reports as follows : — 



Note on Mr. Chrimes's Rain-gauge Experiments, by Joseph Baxendell, Esq., 

 F.R.A.S. — Comparing the quantity of rain received by the horizontal mouth 

 of the five-mouthed gauge with that received by the 90° iuclined gauge, I 

 find that the mean monthly angles of deviation from the vertical of falling 

 rain were — „ , o , o , 



April .... 54 45 May .... 50 22 June .... 35 15 



The mean derived from the entire series of observations (not the mean of 



the monthly means) is 42° 13'. This value is greater than I was prepared 



to expect, but is borne out by the results of the other gauges ; thus, the 



greatest quantity of rain was, in every month, received by the 45° incUned 



gauge ; and comparing the results of all the inclined gauges, we obtain the 



following monthly values : — 



o o o 



April .... 56 May 53 June 37 



The mean daily movement of the wind on rainy days was 149 miles. 

 Arranging the rainy days in two groups, the one including all the days when 

 the movement of the wind was above, and the other all those when it was 

 below the mean value, we find that with a mean daily movement of 103-8 

 miles, the rain fell at an angle of 33° 38' from the perpendicular, and with 

 a mean daily movement of 227-4 miles the angle was increased to 58° 21'. 



The five-mouthed gauge was in use two months earlier than the series of 

 inclined gauges, and the mean monthly horizontal direction of the rain de- 

 duced from its indications was as follows : — 



February S. 74 11 W. 



March S. 25 4 E. 



AprU N. 57 29 E. 



May N. 65 14 E. 



• June N. 46 36 E. 



If I understand the construction of the tipping-gauge aright, it ought to 

 receive more rain than any of the other gauges, but the observations show 

 that while in general it receives more than the horizontal and vertical 

 gauges, it receives less than the gauges whose orifices are inclined at angles 

 of 22|°, 45°, and 67|°. On days when the velocity of the wind is less 

 than the average, the tipping-gauge receives less than either the 22^° or 

 45° inclined gauge, and more than any of the other gauges ; but with the 

 velocity of the wind above the average, it receives more than the horizontal 

 gauge and less than any of the others. It appears therefore to be irregular 

 in its action, and to require some modification before its results can be used 

 with confidence in rainfall investigations. Josh. Baxendell. 



Cheetham Hill, Manchester, August 17, 1866. 



p.S. — So far as I can see at present, Mr. Chrimes's experiments do not 

 throw any fresh light on the question as to the cause of the differences in the 

 amounts of rain received by gauges at different elevations. 



Influence of River Mists on the Amount of Rain collected. — An observer of 

 great practical experience once marked on his return " affected by a large 

 pool adjacent to the gauge." Mr. Symons at once began speculating how 

 much this could amount to ; and it has also often been questioned by those 

 who, from an elevation, have seen the mist hanging over the windings of 

 a river, so marked and well defined that its course can be traced for miles. 

 Is it to these mists, or to the percolation of the water through the river 

 banks, that their luxuriant vegetation is to be ascribed ? If to the mists, 



