TORNADOES. 159 



The tornado cloud may, however, remain at a perfectly safe distance through- 

 out its aerial course and where it may be seen at a great height, moving solitary 

 and alone, like a huge balloon. While in this condition it has, not a few times 

 been unwittingly taken for the latter object, but the mystery and sensation was 

 entirely dispelled when the news came in from the surrounding country of the 

 frightful power of this now silent monster. 



There is still another condition, which the fearful aeronaut may assume in his 

 flighty movements. Upon rising from the earth and passing through a few un- 

 certain struggles, apparently to decide as to whether the final direction shall be 

 up or down, the tornado cloud is ultimately lost sight of in the surrounding clouds, 

 and reappears suddenly again at its point of descension, or perhaps only to 

 remain at a safe distance. 



No. IV. is called the zigzag motion, or swaying from side to side of the 

 central line of cloud movement. This motion is sometimes quite suddenly per- 

 formed, but generally it is a moderately slow movement and one that can be 

 attached and easily identified. It seems to occur most frequently just as the 

 tornado cloud touches the earth in completing the last act of motion No. III. 

 In completing the extent of a single act of this motion, the tornado cloud will 

 diverge about an equal distance on either side of the central line of movement, 

 though these tangents to the major axis are not necessarily of equal length. 



At the commencement of this motion the tornado cloud, always moves first to 

 the left (N. N. E.) and then to the right (E. S. E) forming an obtuse angle on the 

 north side of the major axis. On the return movement, the cloud may or may 

 not cross the major axis (to E. S. E.). If it does, it will then form a similar 

 obtuse angle on the south side of the major axis. This zigzag movement, first 

 from one side and then from the other of the central Hne of progressive action, 

 may continue for several miles, or it may cut short its existence after the first few 

 moves. 



The regularity of this pecular action appears to depend upon indraughts 

 from the south side of the major axis, of violent currents of air, which fre- 

 quently advance (only from the left side) and give evidence of their exist- 

 ence by swaths or narrow paths of destruction (alternating with spaces of no 

 damage) cut inward toward and joining with the central line or track. The 

 tornado cloud may, upon the return movement, whether executed upon the north 

 or south side of the major axis, it matters not, fail to cross it, but upon reaching 

 it continue onward in the central line of movement to the northeast. 



The distance traveled by the tornado cloud in departing from the major 

 axis, either to the north or south, is generally subject to considerable variabiUty, 

 ranging from forty to fifty yards to nearly as many rods. While executing this 

 zigzag motion it very frequently happens that the tornado cloud simply skims 

 over the earth without manifesting its extreme violence. 



Building Spots. — In regard to the matter of buildings, the question maybe 

 asked whether there is not some choice in a building spot, with a view to safety 

 from the violence of the tornado cloud. Many persons have thought that if their 



