248 CLOUD-FORMATION. 



into a very dense black stratus cloud that hung ever the 

 lake, and extended as for up and down the valley as the 

 eye could reach. This cloud was borne away to the 

 westward and precipitated on the Adirondacks in the 

 form of snow. 



On going to the United States Signal Office in this 

 city, I learned from the officer in charge. Mr. Geo. H. 

 Ellerv, the following registry of observations made by 

 him about that hour : Hight of barometer, 30.75 inches ; 

 temperature, 3° ; relative humidity, 46 ; direction of the 

 wind, north with a velocity of one mile per hour. On 

 referring to the U'ccl^/y Wcat/icr Chronicle of the War 

 Department for that day I find therein reported : "Clear, 

 cold weather continued in New England and the St. 

 Lawrence valley." Mr. Ellery also informed me that 

 several times he had reported rain at this station when it 

 was clear weather at all other stations outside of the 

 Champlain valley. 



There is no doubt about evaporation taking place from 

 all our small streams, ponds, and lakes, but that enough 

 takes place to produce clouds, and a precipitation of rain 

 or snow in any considerable amount, is not so clearly de- 

 monstrable as in the Champlain valley, when the mete- 

 orological conditions were all so favorable as on the 

 above-mentioned day. Many days during the past year 

 I have obsen'ed this dark stratus cloud overhanging the 

 lake, and borne eastward or westward according to the 

 direction of the wind, and precipitated on the Green 

 Mountains or the Adirondacks in the form of rain or 

 snow ; inany times light rains or cloudy misty weather 

 is observed in the broad valley between. 



During the fourteen years I was in practice at New- 

 port, on Lake !Memphremagog, I never noticed this cloud- 

 formation. The valley is very shallow, and the area of the 



