LABORS OF THE JOINT COMMITTEE. 163 



upwards in the region of the cloud itself. Is there such a 

 thing as a white squall, without any cloud formed, or about 

 to be formed over the region of the squall ? 



In case of a great storm or hurricane does the wind near 

 the equator always set in from some western point ; and do 

 tornadoes always travel in the direction of the stratum of air 

 which the tops of columnar clouds penetrate ? Or is there 

 any law on this point? Do columnar clouds more frequently 

 form over islands than in the open sea ? And do they only 

 form in the day when the heavens are not overcast with 

 others, and do they disappear in the night as they do on 

 land ? Are columnar clouds formed every day not overcast ? 

 If not, what is the cause ? Is it because the dew point is too 

 low when compared with the temperature of the air ? What 

 is the greatest depression of the dew point below the tem- 

 perature of the air when columnar clouds form ? 



How soon do they begin to form after sunrise, and when 

 do they cease to form in the afternoon? And when do they dis- 

 appear in the evening ? Or is there any law on this point ? 



Mr. Redfield, of New York, has shown that the storms 

 which visit the West Indies, travel north westwardly while 

 in the torrid zone. Does the wind in these storms, which 

 sets in from the north west, change round on the north east 

 side by the north, and on the south west side by the west, 

 in such a manner as to show, that the wind blows towards 

 the centre of the storm ? Or what is the general law on this 

 point? Are these storms always attended with electrical 

 phenomena; and is there any thing peculiar in the appear- 

 ance of the lightning ? When an observation is made on 

 land, note whether the lightning descends vertically, as has 

 been asserted, and rolls over the ground like melted metal. 

 Inquire, when tornadoes occur, whether they sometimes 

 lift up large trees, and set them down in a different place, 

 on the broad base of their roots, without overturning them ; 

 whether they lift off the roofs of houses, and prostrate the 



