=Exercise 257=
Books that will Suggest Topics for Talks
If you have access to a public library, you can probably obtain some of
the following books. They are all simple and interesting, and any of
them will suggest several topics for talks.
ALLEN, N. B., Industrial Studies.
BAKER, R. S., Boys' Books of Inventions.
BARNARD, CHARLES, Tools and Machines.
CARPENTER, F. G., How the World is Fed; How the World
is Clothed; How the World is Housed; Geographical
Readers.
CHAMBERLAIN, J. F., How We are Fed; How We are
Clothed.
CHASE, A. and CLOW, E., Stories of Industries (two
volumes).
COCHRANE, C. H., The Wonders of Modern Mechanism.
COCHRANE, ROBERT, Romance of Industry and Invention.
DOUBLEDAY, RUSSELL, Stories of Invention.
FORMAN, S. E., Useful Inventions.
GIBSON, C. R., The Romance of Modern Manufacture.
LANE, M. A. L., Industries of To-day.
LITTLE CHRONICLE CO., Industries of a Great City.
MOWRY, W. A. and MOWRY, A. M., Inventions and
Inventors.
PARTON, J., Captains of Industry (two series).
ROCHELEAU, W. F., Products of the Soil; Minerals;
Manufactures.
TOWLE, G. M., Heroes and Martyrs of Invention.
WILLIAMS, A., How it is Made.
=Exercise 258=
Study the punctuation of the following; then write from dictation:
1
It is stated that practical experience with gas
mantles made of artificial silk--that is, silk made
from wood pulp--has proved them to be far superior to
those made of cotton, especially where the mantles are
exposed to excessive vibration. Several German towns
are said to be obtaining exceptionally good results
from these new mantles used in conjunction with
pressure gas, and it is asserted that the mantles are
in good condition after being used for seven or eight
weeks. Artificial silk, according to reports, has also
been used experimentally by several manufacturers of
incandescent gas mantles in the United Kingdom. The
reports are all very encouraging, except that there
seems to be one difficulty that is purely
mechanical--the knitting of the artificial silk. The
knots and other imperfections in the yarn cause a
considerable amount of waste. However, the
knitting-machine makers are experimenting to overcome
it.--_Daily Consular and Trade Report._
2
As the production of wool in this country, although
approximating 320,000,000 pounds a year, does not
begin to meet the demands for the raw material, there
is a yearly importation of from 156,000,000 to over
300,000,000 pounds. When each new census reveals the
fact that there are fewer sheep of shearing age in the
country than there were ten years before, the question
of wool production becomes one of still greater
importance. A solution may be found in a Peruvian
product. A variety of cotton grows in Peru whose long,
rough, crinkly fiber mixes so readily with wool that
manufacturers use it in connection with wool in
manufacturing "all wool" goods. It grows on a small
tree that yields two or three crops a year for seven
or eight years. The area, however, in which it is
being successfully cultivated in Peru is so limited
that the annual output is only about 16,000,000
pounds, of which the United States takes approximately
5,500,000 pounds. As the region in which it thrives is
practically rainless, perhaps a way may be found to
persuade the rough Peruvian to make a home for itself
in the hot and arid regions of our Southwest. It would
be a triumph of agriculture, certainly, to raise
vegetable wool in regions not fitted for real
sheep.--_The Wall Street Journal._
3
THE CASTING OF METALS
As is well known, some metals are unsuitable for
casting, while others, like iron, can readily be cast
into any desired shape. The property of casting well,
it is said, depends upon whether the metal contracts
or expands in solidifying from the liquid form. Iron,
like water, expands in solidifying, and hence the
solid metal may be seen floating in the liquid iron
about it. The expansion causes it to fill the die into
which it is poured, and so it can be cast easily. Gold
and silver contract in cooling, and are, therefore,
not suitable for casting.--_Harper's Weekly._