152 
AMERICAN AGRICULTURIST, 
[April, 
TOYS & OT1LS ? OMMMSo 
The Doctor’s Talks. 
Ilat play you accidentally run against another hoy, you 
may hurt him, may even throw him down with great vio¬ 
lence. But how is it with yourself? I recollect that in 
some play at ball or other game I ran against a boy I did 
not happen to see, and while he went down, I struck 
with such force as to “knock the breath from my body,” 
and I suffered so much for a few seconds that I have never 
forgotten it. The boy was standing still, I went against 
him with great force, sufficient to knock him down, and 
I was badly hurt. This is one of the earliest illustrations 
I can recollect of having learned of what is laid down in 
the books as one of the laws of motion, which is: 
ACTION AND REACTION ARE EQUAL. 
If you strike the table with the hand, the table reacts 
with the same force. If you fire a ball from a gun, the 
explosion of the powder pushes the ball in one direction 
and the gun in another ; the ball goes to a great distance, 
the gun moves but little. The force of the powder is 
spent in moving the gun, which is very much larger than 
the ball, and, if the gun is held close against the shoulder, 
is communicated to your body also. When you jump 
from a big rock, you push yourself with a certain force, 
and by the spring of your knees, etc., throw ycurself to 
several feet away. Now you push the rock with the same 
force that you do yourself, and through that the whole 
earth, but these are so vastly larger than yourself that the 
motion given to them by your jumping can not be meas¬ 
ured. If, instead of a rock, you jump from a small boat, 
the case will be different, as the movement of the boat 
will plainly show; indeed, in even stepping from a small 
boat one has to be very careful else he will be a dripping 
illustration of the fact that 
“action and reaction are 
equal.” We see this in 
the flight of a bird ; the 
bird beats the air down 
with its wings, the air on 
the other hand reacts and 
raises the bird. It: row¬ 
ing, we push the oar 
against the water ; the wa¬ 
ter in turn reacts against 
the oar, and the bout is 
sent through the water. 
In our talks about Matter 
and such things, we shall 
have use for a word, and it 
is one that we will now and 
then meet with, which is 
MOMENTUM. 
If you look in the books 
to find what Momentum is, 
you will learn that it is 
“ the mass of a body mul¬ 
tiplied by its velocity,”— 
a perfectly correct defini¬ 
tion, but one which may 
not at first give you a clear idea as to what is 
meant by Momentum. If I were to say that it is “the 
amount of go there is in a body,” it would not be very 
elegant, but perhaps you would understand it better. It 
is the force with which a body in motion strikes against 
another at rest. A stone will easily hold up a hammer; 
we may press the hammer against the stone as bard as 
we are able without changing the stone, but with a very 
quick blow of the same hammer we can break the stone 
at once; in other words, we have given momentum to 
the hammer head—and motion joined to weight will 
accomplish what weight alone failed to do. 
A SMALL BODY MOVING SWIFTLY 
may have a greater momentum than a large one, going 
slowly. Even so light a body as air, when moving rap¬ 
idly, exerts great force, as we see in a hurricane, and 
water in the form of hail, when rapidly moving, breaks 
the glass in our windows, and strips the small branches 
from trees. On the other hand, a large body, though it 
moves but slowly, has great momentum, and can strike 
with great force. A ship, moving so slowly that the mo¬ 
tion can hardly be seen, will come against the pier with 
immense force, and if a small boat should chance to get 
between the two, it would be made into splinters at 
once. When a body in motion strikes another, it loses 
its own momentum, and imparts it to the other ; if the 
second body is movable, it will be set in motion ; if not, 
the effects of the blow will be seen in other ways. Boys 
in their early attempts with tools, learn some lesson 
about momentum. If they try to drive a nail into the free 
end of a board, as in figure 1, they find it very difficult; 
the force or momentum of the hammer does not send 
home the nail, but merely gives motion to the board; 
drive as furiously as you may, the nail will not go to its 
place. An older person may show you, or you may dis¬ 
cover it yourself, that simply holding a block under the 
end of the board, as in fig. 2, will allow you to drive the 
nail at once. In this case you strike no heavier blows, use 
no more force. In the first case, the momentum of the 
hammer was used up in springing the board; in the 
second, it is received by the nail and block together, 
with the effect of driving in the nail. 
Tlie Doctor’s Correspondence. 
PASTE FOR SCRAP-BOOK. 
“ Sarah M. W.,” N. J.—Paste is much better for pasting 
your materials into a scrap-book than any kind of gum or 
mucilage. Stir the flour so thoroughly with cold water 
that there will be no lumps in it, and boil slowly for a 
few minutes ; when cool stir in a few drops of carbolic 
acid to preserve it. Creasote is said to answer as well_ 
We have had first and last some very curious examples 
of insect work, but none that to me seems more wonder¬ 
ful than a bit of stick—a twig of a pear tree that had in 
it a deep groove three-fourths of the way through, and 
as nicely cut as if it had been put in a lathe and turned, 
i The gentleman who sent it from Arkansas suspected 
that it was done by an insect, but he had never been able 
to catch any at work. He was right in thinking it to be 
the work of an insect, and for his benefit, as well as to 
call your attention to it, I give its portrait from Doct. 
Packard’s “ Guide to the Study of Insects.” The work¬ 
man, as you see, is a little beetle 
CALLED “THE GIRDLER,” 
The engraving shows it at work; when the job is finish¬ 
ed, the groove is more nicely done than most of you 
boys could do it with a knife. The insect was first de¬ 
scribed as long ago as 1825, it being then known to work 
upon hickory trees ; but our Arkansas friend writes that 
pear trees are most attacked, its next choice is an apple 
No. 475. Illustrated Rebus.—A leison which it takes some people a 
whole lifetime to learn : a truth over which old and young can well give some thought. 
or hickory, and occasionally it attacks the cherry and 
plum. You do not need to be told that such grooves, 
however neatly made, are very injurious to a tree; it at¬ 
tacks stems as large as your finger, and of course all that 
part of the stem above the cut will die. They have not 
before been known to be abundant, but they seem so in 
the orchard of the gentleman who sent the specimen. 
WHY DOES THE INSECT DO THIS ? 
Some of you may think it is to get food, but the wood is 
not eaten ; if that were the object, she—for it is always 
the female insect that does the work—could get wood 
without the trouble of cutting so deep. She does not do 
it to get food for herself, but to provide her young with 
food, which must be dead wood, and very curiously she 
does it. The mother insect makes holes in the twig in 
which she places her eggs; afterwards she goes below 
the place where she has put the eggs and cuts this groove; 
in time the branch dies, and it being held by a very small 
neck of wood, the winds break it off, but the young 
Girdlers are all snug within, where they can feed upon 
dead wood until they have made their growth; in time 
they will appear as perfect Girdlers, to go on with the 
work. When the female insect has laid her eggs, and 
girdled the twig, she dies; she never lives to see her 
young, but she works on at her girdling, slowly making 
the groove, a minute chip at a time. Isn’t it wonderful, 
this foreseeing the wants of her young and providing 
for them in this strange and peculiar manner 1 
Our Piuzle>SS«x. 
WORD-MAKING PUZZLE. 
(In the following lists of words, one word in each list 
is to have the letter at the end of the list added to it, and 
with it be transposed into another word.—Example. 
List:—boy, reprobate, ladder, rock, stone, reassure, by; 
letter, H. The word in the list to which the letter H can 
be added, is—“ stone;” with H, it can be transposed, 
into honest.) 
1. List: batter, fire, engine, gruel, sense, in, nonsense; 
letter—U. 
2. List: muslin, embroidered, shirt, vest, house, apiece, 
toy ; letter—T. 
3. List: dread, Indians, bugbear, onto, mouth, cotton, 
adapt; letter—M. 
4. List: copse, gate, letters, valued, bit, love, future,, 
galley ; letter—N. 
5. List: history, tale, twice, mine, oyster, knife, in¬ 
crust ; letter—V. 
G. List: book, perusal, picture, incur, my, magic, 
gather; letter—E. 
7. List: cow, student, cant, convoke, coo, hexagon, 
poetry, bond ; letter—I. 
8. List: open, volume, butcher, veal, suet, hearth, 
audit; letter—P. 
CROSS-WORD. 
My first is in awful but not in grand, 
My second is in pasture but not in land, 
My third is in orange but not in plum, 
My fourth is in finger but not in thumb, 
My fifth is in chapter but not in verse, 
My sixth is in patient but not in nurse, 
My seventh is in prison but not in cell, 
My eighth is in clapper but not in bell, 
My ninth is in poison but not in bane, 
My tenth is in torture but not in pain, 
My eleventh is in cracker but not in bun. 
My twelfth is in pleasure but not in fun; 
And now you may look 
In your picture-book, 
And the first one you see 
Is sure to be me. 
NUMERICAL ENIGMAS. 
I am composed of 16 letters: 
My 1, 6. 11, 10. 16. 5, is the name of a river. 
My 14, 12, 4, if you eat it will make you shiver. 
My 12, 2, 1G. 4, 1G, is what many like to eat. 
My 5, 13, 11. 10. is nothing but a cheat. 
My 12, 2, 7. 15, is a part of your face. 
My 11. 1, 6, 16, 8. 5, is the name of a place. 
My 8. 11, 10, 4, is what you have, so have I. 
My 4, 11, 3. 11. 12. 6, 4. often makes infants cry. 
My 9, 11. 10, 16, 5, are what a number play. 
My 10, 7. S. 4, is dark and dismal, so they say. 
My 10, 11, 14, 8, 4, is the name of a State. 
My 9. 11, 1, 4, is where lovers often wait. 
My 9, 3, 11, 10,10, 11, 3, is a useful book. 
My 10, 4. 11, 1, is what women often cook. 
My 3, 11, 7. 8, is what all nations need. 
My 5, 10, 11, 3, 1, is the name of a weed. 
My whole is what all farmers need, 
Without it they must work indeed. A. B. S. 
2 . I am composed of 11 letters: 
My 7. 1, 4, 9, 11, is a level territory. 
My 1, 9, 11, 3, 6, 5, 11, is the name of one of the 
Presidents. 
My 7, 2, 10. 5, is a collection of water. 
My 7, 5, 4, 8, is a sketch of a piece of ground. 
My whole is a subject much agitated. J. B. K. 
1. A daily W. 
2. Emil trin. 
3. Don’t hug us. 
4. Away 1 Scat! 
5. Rob fed a hen. 
ANAGRAMS. 
6. 
7. 
8 . 
9. 
10 . 
Nice Lyne. 
Pet relation. 
A cane by E. 
Only a duel. 
In a strap. 
