630 THK FROST AND DHorcillT OK 1!(05. DOANE. 



3| iiiclios. 1'liis m;iy seem a vci-y small size for the purpose, 

 but this (piostion was investigatod many years ago. After a 

 hiUix scries of experiments it was found that the size of gauge 

 or funnel made practically no difference, as gauges varying 

 from 1 to 24 inches in diameter were used with the following 

 results. The 24-incli gauge, being the largest, the rainfall col- 

 lected therein was taken as 100, ai.id th<' others were found ti> 

 read as follows : — 



Diameter of gauge.. 12 4 5 8 12 24 in. 

 ReadiuP- t>o 'JO 100 U!» 102 102 100 100 



These results show that except in the case of very small 

 gauges the difference in tli(^ amount of rain caugiit never 

 exceeded two per cent. The ado])tion of a size from four inches 

 upwards then came to be a nuitter of convenience, the factors 

 which determine the size being that the instrument shall not on 

 the one hand collect ]ier inch of rainfall an inconveniently 

 small, or, on the other hand, an end)arrassingiy large volume of 

 water. 



The city snow records at the lakes are measured on a board 

 ])lace(l in a carefully selected location where it will be free from 

 eddies and drifts. The board is ])laced level atid the snow 

 falling on it is carefully measured with a rule or scale. The 

 depth of melted snow is ascertained by invertinp- a brass 

 cylinder iJi inches in diameter on the board. Cvlindei- and 

 board are tilicn turned upside down so that the cylinder will 

 contain the actual quantity of snow that has fallen within a 

 circle 3^ i'nches diameter. The snow is melted and measured 

 in a graduated glass in the same manner as rain is measured. 



Tlu' go\'erument observer does not follow the same method 

 for snow measurement, but records the dcjith of melted snow as 

 (Uie-tenth of the depth of snow falling. 



After taking a measui'ement the snow board is aiiain set 

 perfectly level and at the surface of the snow. 



