BLASIUS'S THEORY OF STORMS. 295 



discovered, and came to the following conclusion respecting the origin 

 and distinct character of tornadoes and storms : 



Origin of Storms and Tornadoes. "I had found the existence of two 

 opposing currents of air of different temperature, coming respectively from north- 

 west and southwest, acting suddenly against each other after a sultry calm of some 

 duration; and shortly, a third gyratory force making its appearance between 

 them, traveling in their diagonal, growing to such magnitude as to obliterate all 

 trace of the straight-line forces of the opposing currents, and finally abruptly dis- 

 appearing. The two currents must have been, during the period of sultry calm, 

 in a state of equilibrium, since the clouds were observed to remain for some 

 time almost stationary. South of the tornado's track the southwest wind pre- 

 vailed until the beginning of the tornado, and, from information obtained for me 

 by ex-President Hill, it appeared that a storm had traveled from northwest to 

 southeast over the States of New Hampshire and Vermont, and that during its 

 progress a southwest wind was replaced by a northwest wind. I was thus led 

 to conclude that the storm announced that afternoon by the black bank of cloud 

 consisted in the conflict of two aerial currents of different temperature that the 

 colder northern current displaced the warmer southern current in the direction 

 from northwest to southeast, gradually decreasing in velocity until, north of 

 "Waltham, "West Cambridge, and Medford, it came to a perfect standstill, produc- 

 ing the sultry calm felt before the tornado. 



" Here the two currents, being in equilibrio, exerted a great compressive force 

 against each other. The equilibrium was disturbed by the uneven configuration 

 of the earth around Prospect Hill. This disturbance produced the tornado, 

 which traveled, not in the direction of the storm toward the southeast, but in 

 the diagonal of the two opposing currents over their region of calm at their line 01 

 meeting, and in and underneath the black bank of clouds stretched out from west 

 to east which must have marked this line of meeting. 



" I came thus to two distinct phenomena the tornado, and the storm in the 

 ordinary sense of the word both different in their origin, nature, direction, prog- 

 ress, and appearance, and governed by entirely different laws.'' 



Continuing his observations for several years, he came to the con- 

 clusion 



" That storms in the temperate zone at least, and over the United States, are 

 the effect of the conflict of opposing aerial currents of different temperatures, and 

 not the cause of these currents and temperatures, as seems to be assumed by some 

 cyclonists." 



Continuing and extending his observations and studies in the gen- 

 eral held of meteorology, our author compares his own method of 

 procedure with that usually pursued by others, as follows : 



" Having found, during my investigations, that tornadoes and other storms 

 are different phenomena, and that they follow different laws, I endeavored to 

 investigate storms in general by the same method I had used with the tornado. 



" My researches were not made by filling out the ordinary meteorological 

 formulas from observations made three or four times daily, as is the custom. I 

 had learned that no storm will be accommodating enough to develop itself just 

 at the specified periods for observing ; I do not believe that this method will 

 ever lead to any definite results. 



