62 
THE YOUNG SCIENTIST. 
have caught, to teach you, whenever you 
see others earning what you need, to 
waste no time in fruitless wishing, but ' to 
<jast a line for yourself.' " 
Whistling to a Squirrel. 
ONE afternoon last summer, when out 
looking for game, I sat down on a pile 
of rails to rest. Pretty soon I discovered 
in an oak tree, some twenty yards away, a 
red squirrel stretched at full length on a 
limb taking a sun bath. Instead of rais- 
ing my rifle and sending a ball through 
the little fellow (it's a mighty mean 
"sportsman" that endeavors to kill all 
he sees) I decided to give him a little 
pleasure if I could, so I commenced to 
whistle the air of that once popular ditty, 
" I love Thee, Sweet Norah O'Neil." In a 
twinkling the squirrel was up on his hind 
legs, his tail over his back, his head 
cocked to one side, listening to me ; a 
moment of irresolution, and then he 
scampered down the trunk of the tree 
to the ground and started towards me; 
he came a few yards, stopped, sat up on 
end and listened again. I was careful not 
to move, and kept on whistling; after 
waiting a moment, the little beauty came 
on, jumped up on the pile of rails, ran 
along within four feet of me, halted, went 
up on end again, made an umbrella of his 
tail, tipped head to one side, looked at 
me with all the gravity of a justice of the 
peace at his first trial, and yet if ever a 
creature's eyes beamed with pleasure, his 
did. 
I did not move, but after a little I 
abruptly changed the tune to the " Sweet 
By and By." Chut! Why, with the first 
note of the different tune away went the 
squirrel. I did not move, only I shook 
with suppressed laughter, and, as well as I 
could, kept on whistling. In a minute or 
two back came the squirrel, going through 
all the cunning manoeuvres of his first 
approach, and once more took a seat 
before me on the rails. I w^atched him, 
and actually thought he was trying to 
pucker up his mouth and whistle. 
Once again I changed the tune, this 
time to " Yankee Doodle," and, as before, 
with the first note of change away scam- 
pered the squirrel. Unable to control my 
risibilities longer, I laughed aloud, and 
after that I couldn't call my little friend 
to me. 
I wonder how many of the so-called 
"true sportsmen" ever seek or think of 
any pleasure in connection with such 
beautiful little creatures, save the savage 
and unmanly pleasure of taking away 
their lives.— i^oresi and Stream. 

Common Telescopes. 
THE following description of common 
telescopes, and what may be done 
with them, is from the advance sheets of 
Webb's "Celestial Objects for Common 
Telescopes." The new edition is nearly 
ready, and will be eagerly sought for by 
all amateur astronomers. 
By " common telescopes " are here in- 
tended such as are most frequently met 
with in private hands; achromatics with 
apertures* of 3 to 5 inches ; or reflectors of 
somewhat larger diameter, but, in conse- 
quence of the loss of light in reflection, not 
greater brightness.! The original obser- 
vations in these articles were chiefly made 
with such an instrument— an achromatic 
by the younger Tulley, 5k feet in focal 
length, t with an aperture of 3 7-10 
inches, and of fair defining quality; 
smaller instruments, of course, will do 
less, especially with faint objects, but are 
often very perfect and distinct ; and even 
diminutive glasses, if good, are not to be 
* " Aperture " always means the clear space 
which receives the light of the object; the di- 
ameter of the object-glass in achromatics, or the 
large speculum in reflectors, exclusive of its 
setting. 
t Maskelyne estimated the apertures of metallic 
reflectors and achromatics of equal brightness 
as 8 to 5. Dawes gives this value for Gregorians, 
but, like Herschel II., rates Newtonians as 7 to 5. 
Arago strangely asserted that no light was lost in 
achromatics; but the effects of absorption and 
reflection are so considerable, that with very 
large apertures the advantage of the achromatic 
disappears. The silver-on-glass specula, in- 
vented by Foucault and Steinheil, but perfected 
in England, take their place between the metal 
Newtonian and the achromatic, approaching more 
nearly to the latter, especially when the plane 
mirror is replaced by a prism (which, however, 
does not always conduce to critical definition). 
Buffham assigns equal light to silvered New- 
tonians of 9, and iK, and achromatics of 8, 
5K, and 4 inches respectively. 
t The focal length is measured from the object- 
glass, or speculum, to the spot where the rays 
cross and form a picture of the sun or any celes- 
tial body. 
