162 KANSAS CITY REVIEW OF SCIENCE. 



rods and your position at the centre of that path, it will be seen that you have 

 fifteen seconds in which to reach the outer edge of the path to the north (a dis- 

 tance of twenty rods) before the tornado cloud could arrive at your location. 



I have taken an extreme case in every particular. Most persons first see the 

 tornado cloud at a much greater distance, from one to three miles, sometimes 

 five and ten miles on the prairies. Of course at the unusual distance of five or 

 ten miles you could not determine very satisfactorily its probable course, espe- 

 cially with regard to your buildings or the safety of your own location. Watch- 

 ing the approach of the tornado cloud closely at a distance of ten miles and from 

 that position on and on in its eastward course until it came within a mile or so 

 of your point of observation, would give you sufficient opportunity to predict its 

 probable course in regard to your location. When that matter is settled satisfac- 

 torily to your judgment, move immediately and without further hesitation. If 

 you wait until the tornado cloud is distant one mile you have at least sixty sec- 

 onds in which to run a distance of thirty rods, supposing that you are obliged to 

 cover more than half of the destructive path of the storm. In an average case 

 you will probably have between eighty and ninety seconds in which to run a 

 distance of twenty rods. In either case I am supposing that you are prepared in 

 every particular to move at the very instant of timely warning. Further, I am 

 supposing that you have been watching the weather of the day and understand 

 that a terrible storm is imminent. There is, under ordinary circumstances, 

 no reason why you should not be so informed. A tornado cloud does not come 

 out of a clear sky, and there are many and ample signs of its approach. 



What has been said in regard to the directions in which persons should move 

 when the progressive motion is prevailing, will for all practical purposes apply to 

 motions Nos. I and III. With respect to motion No. IV, (the zigzag the follow- 

 ing preliminary remarks should be most carefully considered. Remember that 

 while possessed of this motion the tornado cloud crosses from one side of the 

 central line of movement or major axis to the other. That this peculiar motion 

 most frequently occurs just after the termination of the rising and falling motion 

 (No. Ill) so that when you see the tornado cloud descending to the earth from 

 one of its aerial flights you may expect (not absolutely) the zigzag motion to fol- 

 low. That the first departure of the tornado cloud from the major axis is to the 

 left or on the north side of the path. That all departures from the major axis, 

 v^\vt\}Oi.tx forward or return movements of the tornado cloud are invariably execut- 

 ed to the eastward. There is no backward movement to the west. That the 

 tornado cloud never continues to move in the direction of any tangent to the 

 major axis but in the event of any departure it ultimately returns to the central 

 line of movement. Having these points well in mind you are quite satisfactorily 

 prepared to act when the exigency occurs. When the departure of the tornado 

 cloud is to the left and your position is at any point in the central line of move- 

 ment (better near the centre of the path) move directly north with the utmost 

 rapidity, even if the cloud is at a long distance from you. Should it chance that 

 your distance from the cloud is reduced to from twenty to forty rods, run in- 



