138 THE YOUNG 
Fish Ponds. 
TO the formation of a flsli i^ond a 
springy piece of ground, a large creek, 
or a small one, or any combination which 
■will furnish a constant supply of fresh 
water, is a prerequisite. 
By attaching a pump, propelled by the 
wind, to a well, you can supply a basin 
from fifty to seventy-five feet in diameter 
and six to eight feet deep, with water suf- 
ficient to raise several thousand carp, or 
other fish. The cost of this pond and ap- 
purtenances need not exceed fifty dollars, 
but excavations can be made to any ex- 
tent to suit the taste or means of the 
owner. The dirt from these excavations 
should be removed far enough not to be 
w^ashed back by rains. The bottom and 
sides need to be cemented or thoroughly 
puddled— that is made of good clear clay, 
moistened and well beaten. This will 
prevent the loss of water by leakage. 
When the basin is complete, place in it a 
small quantity of brush or floating weeds. 
A few trunks of trees, secured to the bot- 
tom, will afford a suitable hiding place for 
the fish, and will prevent marauders steal- 
ing the fish by netting. An outlet as well 
as an inlet for water should be provided, 
and proper screens be arranged so as to 
prevent the escape of fish. If you intend 
to raise carp, do not place other fish of a 
predatory character in the pond. The 
spawning will occur during the spring 
months, the female laying from 50,000 to 
500,000 eggs. The eggs will adhere to 
whatever they touch, and will soon hatch. 
The green scum of a partially stagnant 
pond is fine food for the young fish. Mud 
in the bottom of the pond is beneficial. 
The fish will feed readily on kitchen-gar- 
den refuse, such as cabbage, leek, lettuce, 
hominy, or other substances. 
Water seldom becomes too warm for 
these fish. During freezing weather, they 
bury themselves in the mud at the bot- 
tom of the pond. While in this condition, 
they should not be disturbed. In a pond 
of the given dimensions, several thousand 
fish have annually been taken. If weeds 
and grass grow profusely about the bor- 
ders of the pond, so much the better for j 
the fish. In two years time you can have 
SCIENTIST. 
an abundant and constant supply of sport 
and food, and the advantage of a pond^ 
to assist in beautifying your home. 
Col. Akers, the fish commissioner, of 
Tennessee, while visiting the pond of 
Messrs. Sprewitt & Co., captured a carp 
weighing over a pound and a half, and 
said the sport w^as as good and exciting as 
he wanted. 
The kind of fish to stock the ponds with 
depends upon circumstances. If the 
pond is fed with abundant living springs 
and streams, if the water can always be 
kept clear and cool, trout are undoubt- 
edly the best fish to obtain, in which case- 
the bottom should be covered with coarse 
gravel or small stones, though this is by 
no means necessary. 
How Closely Does a Machinist Measure ? 
IN connection with the question of stan- 
dard gauges and measuring instru- 
ments of perfection, it is interesting to 
notice how closely the machinist works 
with the ordinarij tools of his trade. 
Some little observation of a workman 
engaged in boring locomotive driving 
wheels and fitting shafts to them, led to 
to the following ; 
The wheels were bored with a tool, and 
of a taper ot 1.64 inch in 7 inches. They 
were bored in a remarkably good lathe, 
but not to exactly the same size. A cer- 
tain distance was fixed upon as pro])er 
for the wheel to be forced on the shaft, 
after allowing the shaft to settle into the 
wheel (which was laid down on the floor) 
by its own weight, and the workman 
would not make a variation of more than 
§ inch in that distance. 
Making allowance for want of truth in 
the hole and shaft (although it w^as ex- 
tremely difficult to detect any variation), 
it is safe to say that the machinist was 
working within l-4000th of an inch. To dO' 
this, he must first measure the hole in 
the wheel with his caliper, transfer that 
measure to another pair of calipers, and 
again transfer that measure to'the shaft 
he was turning. Making allowance for 
the fact that a machinist cannot turn as 
fine as he can measure, it may be safel}'- 
concluded that he will work so closely, 
that the variation will be scarcely notice- 
able in a fit. However closely he may 
work, the fact should not be lost sight 
of, that he cannot define the size to which 
he is working, without the use of some- 
sort of a measuring instrument of perfec- 
tion. In other words, he can work almost 
infinitely closer than he can measure, by 
the use of ordinary tools— American Ma- 
chinist. 
