THE TORNADOES OF APRIL 18, 188o. 53 
It is almost impossible to indicate the paths of these storms from the data at 
hand, but the Signal service charts and reports, when fully made up, will doubtless 
give to the meteorologists some very remarkable information and suggestions. 
The early appearance of tornadoes this year in this latitude seems to be 
exceptional. The equatorial wave of high temperature appears to have drawn 
them forward nearly a month. Tornadoes will occur whenever the conditions 
are supplied, and will of course appear earlier with premature heat. 
I wish simply to call attention to the fact that the Marshfield tornado con- 
forms as far as known to the physical laws as explained by the thermal theory.. 
Prof. Tice, who holds to another theory, in his report of the tornado, says: 
‘< Everywhere along the track of the tornado there is evidence of a wave of 
water flowing in the rear of the cloud spots. At some places there are only faint 
traces of such a wave; at others the debris is carried up and over obstructions 
of from two to three feet high. These waves or currents flowed in greatest volume 
up hill. There are places where the entire top soil is washed away by the cur- 
rents. Fibrous roots and tufts of grass show their direction to have been up hill, 
and what is significant, from all points of the compass to the top of the hill where 
the tornado was raging at the time and expending its force. No trace can be 
found at any point where they flowed down hill. Many level places are swept 
clean of soil. Leaves, grass and debris of the wrecked buildings, fragments of 
plants carried along by the current and left in its track had arranged themselves 
longitudinally to the current.” 
This reported wave is evidently only the great condensation of vapor rushing 
from all directions into the core of the tornado. 
Colonel R. T. Van Horn, in discussing the fact that tornadoes follow the 
isothermals, says: 
‘«The cause is the meeting of two waves of air at different temperatures, and 
-where should that meeting be more marked or the effects produced of as great 
intensity, as on the line that marks the mean between the two conditions? If 
there is a general law that governs in their origin and formation, there must be 
one that controls in their movements. And we have traced enough of them on 
the isothermal maps to be satisfied of the fact that their movement does corre- 
spond to these lines of mean temperature.” 
If tornadoes follow the lines of mean temperature must there not be some vital 
relation between them and heat? This is what is claimed by the thermal theory. 
Electricity seems inadequate as the cause of the tornado or for the produc- 
tion of the fundamental movements. Why does electricity revolve the tornado 
north of the equator in the direction contrary to the hands of a watch, and south 
of the equator in an opposite direction? Why does electricity cause tornadoes 
to move along the lines of the isothermals northeasterly? Why do not some 
of them, even if only for variety, move in an opposite direction? ‘True, light 
substances under a charged receiver will be attracted toward it to restore the 
equilibrium. But will electricity, as in a tornado in Georgia, carry up a tree, 
