1879 *] Tornadoes of Kansas and Missouri. 619 
error only) being 28*670. At 7 p.m. the wind suddenly 
backed from south to north and increased in force, blowing 
for about five minutes at the rate of 60 miles per hour. The 
cloud then moved rapidly southward, trending toward the 
east. The rain fell in perfect torrents for near an hour. 
From 7.10 to 7.40 p.m. considerable hail fell: a number of 
stones were measured and averaged from J to f of an inch 
in diameter. The electrical discharges were very intense 
and almost constant. The force of the storm expended it- 
self about 8.5 p.m. The rain ceased at 8.15 p.m., and the 
amount which fell in one hour and forty minutes was one 
inch and forty-three one-hundredths. 
“ The storm produced no serious damage in this city or 
vicinity. A large number of trees in the city were blown 
down, and several large buildings suffered damage by lifting 
of roofs. Fruit trees and growing grain were somewhat 
damaged by the hail. The position of fallen trees, in dif- 
ferent portions of the city, plainly indicated the spiral motion 
of the wind. The large iron bridge over the Missouri river 
at this point, on which was a train of heavily laden cars, 
swayed so much that the engineer jumped from his engine, 
thinking the bridge was toppling over. 
“ At about the same hour, a very destructive tornado 
struck the earth north of this station, near St. Joseph, Mis- 
souri. No doubt the disturbance felt here was an offshoot 
of the above mentioned tornado. 
“ During the evening, from 9 to 11 p.m., the electrical 
display in the south, south-east, and east was very beautiful 
and vivid. The heavens were almost continually illumi- 
nated. Frequently there were seen as high as a dozen 
streaks of lightning, of the zig-zag form, which seemed to 
radiate from a common centre.” 
Several theories have been advanced in reference to the 
causes of tornadoes. In the present article I have only 
space to discuss one of them. 
Storms are supposed to find their origin, according to the 
Thermal theory, in an unstable equilibrium of the atmosphere 
due to solar heat. About three-fourths of the sun’s rays pass 
through the atmosphere, and are absorbed by the surface of 
the earth. The envelope of the earth is thus heated mainly 
at the bottom, while it loses most of its heat by radiation at 
the top. As an increase of heat diminishes the density of 
the air, the envelope of the earth is in a constant state of 
unstable equilibrium. The upper and heavier strata of the 
atmosphere tend constantly to descend and force up the 
lower strata. Vertical currents are thus formed over greater 
