178 



FOREST INFLUENCES. 



sand and were just able to drop the sand into the windward gauges while carrying 

 the rain on to the leeward gauge. In accordance with the preceding explanation all 

 observations every where show that the higher gauges have the larger deficit in rain 

 catch and still larger deficits in the snow catch, and that both deficits increase with 

 the wind. 



Mordecai states (Journal Franklin Institute, 1838, vol. xxir, p. 37) tliat he arranged 

 his observations at Frankfort Arsenal to show the rain catch at the ground and on 

 the tower 52 feet high according to the force of the wind as estimated by him on the 

 scale to 10 as used by him, and found the deficit of- the tower gauge to be per ceut 

 for calms and light winds, but increasing steadily up to 36 per cent for a wind of 

 force 8. 



Bornstein (Met. Zeit. Oct. 1884) arranges the catch in protected and unprotected 

 gauges according to the velocity of the wind, and for seven mouths of observation 

 obtained the following deficits in millimeters, to which I add the same converted 

 into percentages on the assumption that the protected gauge is practically equiva- 

 lent to the pit gauge. This assumption, although it is not quite correct, will not 



much change our results: 



Taule I. 



The distinction between the effect of the winds in heavy rains and fine rains is 

 very clearly brought out by Bornsteiu's classification of the catch on twenty-six 

 days of fine rain aud forty-three days of heavier rains; the percentages are as shown 

 in the following table : 



Table II. 



Mthough all these preceding data, both by Mordecai and Bornstein, are limited 

 in quantity, yet they conspire to show uniformly the same effect of the wind that is 

 shown in an exaggerated scale when the ordinary gauge is used to catch snowfall. 

 Similar results based on a somewhat larger series of observations are published by 

 Wild (Repertorium for Met., vol. ix), as shown in the following Table III, which 

 gives the percentage of catch during winter's snow and summer's rain separately for 

 several altitudes aud wind velocities : 



