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REVIEW. 95 
patches are divided and touched with white ; in the succeeding 
segments the patches are further touched with white, and fre- 
quently ocellated with this colour ; below those groups of black 
are yellow streaks; lateral stripe white ; a row of black tubercles, 
bearing hairs, runs along the edge of the underside ; underside 
greenish ; white hairs on the back; head light brown, with a 
dark triangular patch, having a white mark at its base; 
mandibles dark ; ten pro-legs ; cococns formed at the top of 
their cage, of white silk ; chrysalis, light yellowish brown. 
Boarmia attracta—A female caught about the end of March 
laid a number of eggs. Eggs oval, bluish-green, slightly de- 
pressed, with regular hexagonal reticulations. The larve were 
brownish red, with a white lateral stripe. I could not find any 
plant they would eat. 
Cidaria simtlata—In December a female laid about thirty 
eggs. Eggs oblong, smooth, green, scattered singly and gene- 
rally laid on their side. They turn red before hatching. 
Helastia Sp—Caterpillar looping, green, about two-fifths of 
an inch long ; an indistinct dorsal and subdorsal stripe of darker 
green; underside green, with a light ventral stripe; head 
yellowish. Formed small rough earthen cocoons on the surface 
of the earth. The food plant is Wyoporum laetum. 
REVIEW. 
“A GREAT MATHEMATICAL QUESTION.” By T. Wakelin, B.A. 
In this little pamphlet there are about 15 pages of matter, 
and of these about seven consist of extracts from Whewell, 
Stewart, and others. We have read it through very carefully, 
and have to confess that we cannot see that the author has made 
any addition to our knowledge of kinetics. The tract appears 
to us to have grown out of a want of appreciation on the part 
of the author of the distinction between momentum, kinetic 
energy, and work done. Take the following passage as an 
example of the confusion of work done with energy of motion. 
Speaking of the work done by raising a ball a certain number of 
feet, Mr. Wakelin says: “If the ball weighed 10 pounds, and 
had risen to a height of 800 feet, 8000 foot-pounds of work 
would have been done in lifting the ball to the height stated. 
Now, it is found that, if the velocity of the ball had been 
doubled, it would have risen, not to double, but to four times 
the height ; and if the velocity had been trebled, it would have 
risen, not to treble, but to nine times the height, and soon. The 
work done then by the moving cannon ball will vary, not simply 
as the velocity, but as the square of the velocity.” It is hardly 
necessary for us to say that the work done has nothing what- 
ever to do with the guzckness with which it is done. Work done 
is simply mass multiplied with height, irrespective altogether of 
