108 M. Flaugergues on the Quantity of Rain, and [Aug. 



requires little trouble in using, it exhibits opaque objects in a 

 manner superior to any instrument which I have ever yet 

 inspected, and may be constructed at a considerably less 

 expense. 



Article V. 



Memoir on the Quantity of Rain, and the Number of Days 

 of Rain, Snow, and Drizzle, at Viviers, during 40 Years 

 {Lat. 44° 29' 1" N. Long. 2° 20' 55" E.from the Meridian 

 of Paris, 30 Toises above the Level of the Sea). By M. Flau- 

 gergues.* 



Th e rain gauge which I employ for measuring the rain water 

 that falls consists of a square vessel of tin plate covered with oil 

 paint, the opening of which, constituting the mouth, and the 

 bottom, are each six inches square. This vessel is placed in the 

 town in the middle of a spacious court, on a small stone column 

 raised six feet nine inches above the pavement, and not screened 

 from the sky in any direction. As soon as the rain has ceased, 

 I measure the water which has fallen into the gauge by pouring 

 it into a glass cylinder accurately divided into half cubic inches 

 in the following manner : I poured successively into the cylinder 

 placed horizontally equal quantities of rain water of the temper- 

 ature 10° (50° Fahr.), weighing each 187*25 gr. (153*61 gr. troy), 

 which is the weight of half a cubic inch at that temperature .+ 

 After every addition, I marked upon a slip of paper, pasted to 

 the cylinder, the height of the water. I then numbered these 

 lines, and covered the paper with varnish, that it might not be 

 removed from the glass by humidity. The interval correspond- 

 ing to a cubic inch being more than two lines, it was easy to 

 estimate the eighth part of that quantity, which corresponds to 

 •J,- line of height in the rain gauge. It is evident, since the 

 surface of the rain gauge is 36 inches, that 36 cubic inches of 

 rain collected in it are equivalent to a depth of rain of one inch, 

 and three inches collected in the gauge are equivalent to one 

 line of rain in depth. It is according to this ratio that I have 

 reduced to inches and lines of height the quantities of rainwater 

 fallen into the guage and measured in cubic inches. 



With respect to snow, which is merely congealed water, I 

 measured the water which it produced, when melted, in a close 

 vessel at a moderate heat. J I took the same method with 

 hail. 



* Translated from the Bibliotheque Universelle, viii. 127. The difference 

 between the meridian of Paris and of (ireenwich is 9' 20" in time. A Freuch toise 

 = 1 6 7.344 English inches. 



+ The French half cubic inch is equal 0-&0&15 English inches; the weight of 

 tvhichat 5: 10 is ;i very small fraction of a grain less than stated in the text.— T. 



X When the depth of the snow stu nassed six inches nine lines (the height of my 



