134 THE FLYING SQUIRREL. 
clude that they are all ready, out pop their heads, each to be 
followed by the rest of the body, after a glance on all sides with 
the glistening black eyes} and now all drowsiness has disappeared 
and an activity more incessant and intense than can be described 
takes its place. All night long, often with only the briefest rest 
now and then, these little animals are in vigorous motion, jump- 
ing, bounding, capering, running with ever varying movement and 
astonishing energy. Everything they do is done with all their 
might. It would seem to any one watching them that the exer- 
cise of the first few minutes must wholly exhaust their powers, 
but, on the contrary, the more their muscles are used, the more 
capable of use they seem, and great as is the energy of their move- 
ments at first, they usually increase in vigor and speed until after 
midnight and scarcely grow less before morning. Nothing affords 
them so much gratification as a large wheel which is placed inside 
the cage. Into this wheel they jump whenever aught disturbs or 
pleases them, and even when quite hungry they often find it neces- 
sary to take a few turns before commencing their meal, after which 
exercise they draw themselves into a bunch with the tail over the 
back after the manner of squirrels, and set briskly to work on the 
nut or other food which they may have received. They are almost 
as fond of riding as of running and work their passage by run- 
ning till the wheel is in rapid motion and then clinging to its wires, 
and so are carried around and around, the pure white of the under 
side of the body contrasting prettily with the soft brownish-gray of 
the back and sides as each comes into view. When both are in the 
wheel one often rides while the other turns the wheel, the latter 
bounding over the other as each turn brings him around, and, no 
matter how rapidly the wheel turns, these movements are executed 
with perfect exactness and gracefulness. Being desirous of know- 
ing with some degree of accuracy how rapidly the wheel moved, I 
made some experiments for that purpose and found that the usual 
rate of revolution was from sixty to over a hundred and twenty 
times a minute, and, as the wheel is forty-four inches in circumfer- 
ence, when its rate is the latter of the two numbers named, the 
- squirrel turning it must travel four hundred and forty feet a min- 
ute, or about five miles an hour, a distance requiring a great many 
_steps when they are so short as squirrels must take. The sides of 
the wheel are formed of spokes Eg as in any wheel, these 
E are only five inches pen at the circumference and of 
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