LABORS OF THE JOINT COMMITTEE. 159 



out being under the eye of several observers ; and thus it 

 is hoped the exact direction in which all the storms move, 

 and their velocity along the surface of the earth, will, in a 

 few years, be found out. 



When no remarkable changes are going on in the atmos- 

 phere,, three observations will -be sufficient in the day, at 

 seven, A. M., at two, P. M., and at nine, P, M., or as near 

 those hours as possible, always noting the hour and minute 

 when the observation is taken, in case a storm is progress- 

 ing. 



Much curious information, and valuable to the farmer, 

 would be obtained, if our correspondents would, in clear 

 calm nights, observe the difference of temperature of the air 

 at the bottom of the hollows, and on the slopes of surround- 

 ing hills and tops of knolls. They will find, at a certain 

 height, that the temperature remains nearly constant, while, 

 at the bottom of the valley, the change is very great ; and 

 from this investigation they will -learn at what height it will 

 be best to plant their orchards, to prevent their fruit from 

 being killed by frost. Any information which our corres- 

 pondents may give us on this subject, or any other such 

 as frosts, dews, fogs, clouds on sides of mountains, and their 

 height in connection with the dew point, will be thankfully 

 received, and be added to our common stock of knowledge. 



Especially if a land spout or tornado passes near you to 

 the north or south, carefully ascertain the angular height of 

 the cloudy pillar, where it joins the black cloud above, by 

 placing yourself in such a position as to have some fixed 

 object between your eye and the top of the pillar or spout, 

 and afterwards the angular height can be ascertained by 

 the quadrant, and so the height of the spout be known by 

 trigonometry ; for the distance of the observer from the path 

 of the spout can afterwards be measured. Do riot fail to 

 take the dew point and temperature of the air at the same 

 time ; and if, at any time, you should be able to see the top 



