314 THE POPULAR SCIENCE MONTHLY. 



reactionary upward movement through the center of the funnel. This 

 center is almost a vacuum surrounded by a cylindrical mass of air of 

 great density and revolving force. Professor William jNL Davis, of 

 Harvard College, whose work, entitled " Whirlwinds, Cyclones, and 

 Tornadoes," is well known for its merit and originality, maintains that 

 the destructive power of a tornado is due to the rush of air along the 

 earth's surface toAvard the vacuum center of the funnel. Some build- 

 ings have a stricken, pinched appearance at the top, as if the air had 

 rushed under the edge of a huge cylinder, and swept upward with tre- 

 mendous power. While it is true that the downward movement pre- 

 dominates, yet the upward movement in the center is equally marked. 

 The iron grip of the tornado-funnel is relieved only by the escape of 

 cui-rents to the upper air through its center, and this again is doubt- 

 less due to the decrease of the contrasts of temperature between the 

 opposing currents, thus gradually lessening the air-movement. In the 

 Westwood tornado, when the funnel had gone about a mile northeast 

 of the village, it became thinner, and the distance to the top of the 

 revolving column did not seem more than one hundred feet. As its 

 force still further weakened, it became only a shallow, whirling cloud 

 of debris, six or seven feet above the ground, and about fifty feet in 

 width. These facts present a problem of the relation of air-pressures 

 in which we may look for destructive action m proportion to the 

 height of the column of revolving air. 



Lieutenant Finley's interesting studies will soon be of great service 

 to the people. The advancement of the science of meteorology, as 

 well as of other sciences, has always been made through those whose 

 energy in the examination of these subjects has been manifested as an 

 intrinsic liking, regardless of personal gain, a characteristic pointed 

 out long ago by Jean Paul Richter, and reaffirmed by Emerson as the 

 true aim of the scholar. It has been thought that the time will come 

 when greater numbers of men of leisure and means will become steady 

 workers along paths of unprofitable public usefulness. The people 

 look for science to come to their rescue regarding certain evils in poli- 

 tics or in commerce, in over-legislation, in physical and mental life, 

 and in the destruction of life and property by the elements. It does 

 not follow that the service will be rewarded, yet the control or antici- 

 pation of any form of destructive action in Nature is a benefit that 

 will live in the annals of the race for many a century. 



