64 THE TROCHOIDED PLANE. 
moving from N.E. to 8.W., the under surface almost touching the 
tree tops, moving from §.W. to N.E. Sometimes the thunder- 
storm comes without this characteristic cloud, sometimes there are 
T am correct in saying he does not account for its formation in 
this manner. If we substitute the trade winds, equatorial calms, 
and return trade winds for the sea-breeze, plenum, and return 
S.W. er current, the result is one or more hurricanes or 
cyclones, instead of the roll-clou 
Allied phenomena are those witnessed when a drop of water 
falls into water; if the drop falls from a short distance, only 
ring waves are formed ; if from a height, the drop seems to m 
a hole in the water, as well as the ring waves, and the closing up 
of this hole sends up a peak with sufficient force to detach another 
drop from its point. 
Also, if a large drop be allowed to fall from a height, it will be 
seen that after it has attained a certain speed it will leave its 
spherical shape and spread out into an irregular ring ; the move- 
ments of the particles of the ring being similar to those composing 
a smoke ring. 
But to return to the spherical wave; if one of the central 
particles bears an infinite proportion to the other particle, the 
vibration of the smaller one will send waves through a sphere 
surrounding both, resulting in an equal vibration of the antipodes 
of the smaller particle. 
When this action of spherical waves is applied to the supposed 
string of spherical particles composing the axis of a cylindrical 
it i i at we m i 
pulsations be produced in a pipe covering the cylinder, the waves 
aa communicated from the inside of the pipe to the contained 
matter. 
