144. 



Observations 

 on rain and 

 r^m gauges. 



APPENDIX TO THE METEOROLOGICAL JOURNAL. 



crty in the same, as to become filled with a fine mist, which 

 is uUimately resolved into clouds and rain, we shall per- 

 ceive, that a set of rain {gauges, placed at various heights 

 within this portion, ought to collect less and less rain, as we 

 ascend; since each stratum deposits its own redundant wa- 

 ter, and transmits that of the higher ones. 



But if the source of the rain be in a middle current, the 

 lower part of which is above all the gauges, they ought all to 

 afford like quantities; unless, indeed, the lower air be so 

 dry, at the same time, as sf»mewhat to lessen the bulk of 

 each drop by evaporation; in which case, (as is said to have 

 happened in some instances,) the products will be found 

 larger as we ascend. 



Bi*t there is another source of discordant results, which 

 seems not to have been enough attended to. It exists in 

 the deflection of the rain by accidental currents. On th* 

 25th of the ninth month, finding in the gauge, No. 2, 0*4(5 of 

 an inch, while No. 1 had only 0*12 of an inch, I suspected 

 that the wind, which came in squalls from theVV., had a share 

 in producing the difi'erence. I took, therefore, two other, 

 gauges. No. 3 and No. 4, snd on the 27th, placed No. 3 in 

 the gutter, near and on a level with the W. parapet of the 

 house, and No. 4 about 20 feet in a line to leeward, at the 

 same height, but sheltered between the roofs. It was then 

 beginning to rain in moderately large drops; wind fresh at 

 S. W. After two hours and a half, I found in No. 3 0'0&, 

 and in No. 4 0*1 1 of an inch ; No. 1, on the ground, having 

 also 0*11 of an inch. I removed No. 4 about 40 feet to lee- 

 ivard, near the E. parapet, and got in an hour and a quarter 

 from No. 1 08, No. 2 0-15, No. 3 0-12, No. 4 0-14 of 

 an inch. The rain continued six hours, with a steady wind, 

 and was at times heavy : near twice as much fell on the 

 ground gauge as on that at the turret; and the results of 

 the other gauges proved, that some part of the difference 

 must be attributed to the wind. It appears, that the stream 

 of air, obstructed by the W. front of the house (which 

 has a contiguous building fronting S.), and rising in a curve, 

 carried with it a part of the rain over the windward guage, 

 to let it fall on the leeward ; for the latter had more than its 

 due proportion, the former less. 



Thus 



