2 to ILLINOIS STATE HORTICULTURAL SOCIETY. 



carried up from the surface of the earth by this upward current can hardly 

 be estimated, and would probably not be seen by those outside of the 

 vortex of the storm, for it would most likely return to the earth in con- 

 stant flashes, inside of the rising cloud of dust and vapor where the con- 

 duction would be best, and the air would offer the least resistance — on 

 account of the vacuum caused by the vorticose motion. It is evident 

 that the progress of the storm must continue just as long as the causes 

 which produced it exist, to wit : moisture and rapid condensation. Still, 

 if I had the time and you the patience, I think I could point out some 

 circumstances which would either check or divide the vorticose motion, 

 or give the storm a more general cyclonic character. Before speaking of 

 the direction in which the tornado will probably move, I will explain, in 

 part, a well established law upon which this would depend. The law is, 

 that all currents moving in any direction, tend to the right of that line of 

 direction, in the northern hemisphere, and to the left in the southern 

 hemisphere. I will demonstrate this law by an illustration from physical 

 geography, which will help us on our way in the study of storms. The 

 heated air in the equatorial regions rises, and in the northern hemisphere 

 floats towards the north, and this is called the equatorial current, while 

 the colder air from the north rushes in, near the earth, to fill the vacuum 

 thus occasioned, and constitutes the polar current. Now the whole 

 atmosphere partakes of the axial rotation of the earth towards the east, and 

 on account of the spherical form, that part which is near the equator has 

 a much greater eastward velocity than the polar regions, consequently 

 the equatorial current, which retains this eastward velocity, would, in its 

 progress north, have a relative eastward motion over the surface of the 

 earth, and for similar reasons the polar current, which has a lesser east- 

 ward velocity, would constantly swerve from the meridian upon which it 

 started, and have an apparent westward motion. So if two columns of 

 air on the same meridian, should from any cause move towards each 

 other, as in the beginning of a tornado, they would not meet, but the 

 one from the south would turn to the east, and that from the north would 

 turn to the west, and thus they would pass each other by each turning to 

 the right, and this alone is sufficient to account for the whirl and direc- 

 tion of the tornado. It will be readily seen that the eastward velocity of 

 the south wind would be greater than the westward motion of the north 

 wind, so that the whole gyrating mass of the tornado should take an east- 

 erly, or northeast direction. This course would, however, be greatly 

 modified by the surface of the surrounding country, and if hills and forests 

 should check the inflowing currents on one side, the vortex of the tornado 

 would sway towards the obstruction by the greater force of the opposite 

 currents. Thus you will see that there are no mysteries pertaining to this 

 destructive meteor which can not be readily solved by the application of 

 simple, natural laws. 



The limits of this paper will only permit a suggestion to what is 

 called an atmospheric wave, that sometimes sweeps over this whole coun- 

 try, generally from the northwest, but occasionally from other points of 

 compass, as on the 4th of December, when it came from the southwest. 



