W. Ferrel— Cyclones, Tornadoes and Waterspouts. 45 
initial gyration and of friction. In a tall, slender column of 
gyrating air the friction is small, and the oyratory velocity may 
be assumed to be very nearly inversely as the distance from the 
sae except very near the center, where the gyratory velocity 
mes almost infinitely great. Without any friction the 
weaterapdirt would always be brought down to the earth, it 
might be in the form of a mere thread, however small the ini- 
tial gyrations, but in nature, where friction, at least near the 
center, must diminish considerably the velocity of the as. 
this is not the case. The diameter of the base of the wa 
spout depends upon the gyratory velocity, and where pe on 
account of friction near the center, is not sufficient to bring the 
spout down to “ene surface of the ‘earth, it is seen merely as .a 
funnel-shaped clou 
Small waterspouts sihcon are seen upon the sea or small 
lakes in perfectly clear and calm weather, arise from a state of 
unstable equilibrium of the clear but nearly saturated air near 
the —— of the water. The principle of their formation is 
the s but a greater rate of decrease of temperature with 
ices of altitude is required, than when their first formation 
ing currents so ong as the rain is not carried up where the air 
ows out from the center. Calculation shows that the amount 
of rain condensed from nearly saturated currents of air with 
such velocities as must exist in the central parts of tornadoes 
is enormous. The water cannot fall in drops on account of the 
strength of the current. It therefore accumulates in the body 
of the cloud, and especially at points where the ascending 
current is least, until the weight of water becomes so great that 
itis poured down t rough the air in streams. Where these 
streams strike the earth’s surface they excavate great holes in 
the earth, often several yards deep, and if this occurs on a 
sen of these holes are often cut down almost expenitieciahs 
while leaves and other light substances, where these holes occur 
on mountain sides, remain undisturbed near the border on the 
upper side. The ascending current keeps rain-drops from fall- 
ing, so that no water falls except in the down-pourin — 
ud-bursts are most apt to occur on mountain icles 
tornado, heavily loaded with accumulated rain-water, on a. 
pro aching a mountain side is very much interfered with by it. 
