GRISCOM ON METEOROLOGICAL OBSERVATIONS. 345 



observer can conveniently do it, in all remarkable states of weather, more 

 especially with respect to winds and storms. 



The height of the place of observation, in feet, above the level of the 

 sea, should be carefully ascertained. 



We deem it of some importance to remark, that of the several 

 methods practised of registering the daily heights of the thermometer 

 and barometer, that which may be called the graphic method, which 

 consists in drawing a line in conformity to the elevations and depressions 

 of the mercury across a sheet, divided by lines which correspond with 

 the scale of the instrument, appears to be preferable to any other. It 

 might be best, however, at least once a day, to note, in numbers, the 

 precise elevation. 



3d. The amount of condensed vapour, 



The instrument principally to be relied upon, for this purpose, is 

 the pluviameter, or rain gauge. 



We deem it unnecessary to point out what we conceive to be the 

 best method of constructing this instrument. The committee which 

 shall be chosen to execute the orders o the society in relation to 

 the subjects of this report, will, necessarily, avail themselves, in 

 directing its construction, of such hints given by the best writers 

 on philosophy, as they may think worthy of attention. The instru- 

 ment should be placed as near the surface of the earth as circum- 

 stances will admit; as it is well ascertained that, in such a situation, 

 more rain will be caught than in a position considerably elevated above 

 it. As an accurate employment of the rain gauge is particularly de- 

 sirable, the careful attention of the observer will be requisite, during 

 the fall of snow, to collect exactly that portion which falls within the 



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