1820.] 0)1 Rain-gauges. 271 



o-radually sheltered from it in approaching the ground, must 



obviously descend in curves ; let H I, K L, 



with the curves between them, represent the 



paths of the falling drops. Then since it is 



evident these curves must all be every way 



equal and similarly situated with respect to the 



horizon, it follows, that any line H K parallel to 



the horizon must be exactly equal any other parallel I L ; so 



that the general obliquity of descent was no concern whatever 



with the quantity of rain which the gauge receives. 



" Should th'e rain," says Mr. Holt, " be blown in a direction 

 parallel to the horizon, it is obvious none could enter." He 

 might easily have added abundance of other remarks equally true, 

 but like that altogether foreign to the point in question. Since 

 it is not difficult to show that no wind running parallel to the 

 horizon can ever carry rain drops also parallel to the horizon,, 

 until the velocity of that wind become infinite ; and when that 

 takes place, your correspondent would do well to look out for 

 the nearest place of shelter. 



From what I have shown above, we may venture to conclude 

 that there is very little reason for constructing a particular sort 

 of gauge to counteract a source of error which does not exist. 

 Indeed admitting the opinion of these learned gentlemen to 

 have been correct, the quantity of rain which falls on any given 

 space of ground during wind would be less than what came away 

 from the same area of cloud. Query — Is the rest annihilated, 

 or what becomes of it that it does not reach the earth? 



I formerly stated as my opinion that the paradox in question 

 was some way owing to the obstruction which the gauge itself 

 offers to the wind. This idea (the first of the kind I recollect to 

 have met with) has so highly pleased Mr. Holt, that he has con- 

 descended to give it in a slightly different form, as if it were 

 entirely new and his own. 



Until some unexceptionable method be discovered for esti- 

 mating the error to which gauges in an exposed situation are 

 liable, I do not conceive such gauges are entitled to any notice 

 whatever ; and since that error must be affected with the size of 

 the rain drops as well as with the velocity of the wind, I despair 

 of ever seeing the matter put to rights. But if Mr. Holt will be 

 so good as consider the subject with a little more attention, I 

 hope " it v.ill appear to him that he himself has taken the wrong 

 Tiew of it." 



I am, Sir, your most obedient servant, 



Henky Meikle. 



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