Juniata sentinel and Republican. [volume] (Mifflintown, Juniata County, Pa.) 1873-1955, 1878-09-25
SCIENTIFIC.

The Strength OF Wroaaht-Iron. - A
series of experiments has been carried
on at the Washington Navy Yard, by
Commander L. A. Beardslee, of the
United States Test Board, to ascertain
the strength of iron used i'm chain
cables. 1t had been suspected, with Just
reason, that the British Admiralty
tables for the strength of wrought-iron
needed revision. Not less than 1000
tests of the tensile strength of iron have
been made at the Navy Yard, to deter
mine the elastic limit, elongation, and
reduction of area of the various speci-
mems; and AZ complete chemical an
alyses have also been performed. Some
of the conclusions which have been
reached are remarkable. The Admiralty
tables are declared unsafe, and new
ones have been prepared. The Board
finds that the tenaclty of twO-inch bar
for chain cables should be between 49,
900 and 30 coo pounds per solid inch !;
one-inch bar, between 90 900 and 81 900 !;
and that stronger irons than these make
inferior cables, because they have less
ductility and capacity for welding.
The strength of wrought-iron and its
welding power are influenced quite as
much by the reduction it has undergone
in rolling as ordinary differences in its
chemical composition. In general, the
processes for making wrought-iron
give an uncertain quality of the product
while the methods of making cheap
steel confer certainty and uniformity.
The ordinary practice of welding is
capable of great Improvement, by being
performed in an atmosphere freed from
oxygen. The Importance of the sub
ject will be conceded, since the safety of
human lives must often depend upon
the strength of a ships cable, or of the
links in bridge cham.
4 Tomato Disedse.-M. Garcin has
called the attention of the French
Academy TO disease which has, during
this year, attacked the tomatoes in the
Maritime Alps. The malady made its
appearance in the form OF a whitish
efiiOrescence on the surface of the fruit
Suspecting it to be due TO the presence
of parasitic fungus. NJ. Garcin ex-
amined some of the matter with high
power of the microscope. 1t was seen
TO be composed OF a mycelium of white,
septate threads, finely granular at GER
lnC iSi vi
each of the ramifications was swollen
and filled with spores. Free spores
mingled with the mycelium; and the
presence OF zoospOres, of still larger
dimensions showed the fungus TO be in
full fruit. NJ. Garcin believes, there
fore, that he is correct in referring the
parasite to the genus botrytis, several
species of which are already well
known. He calls attention to the fact
that this season, for the first time in
many years, the nluScdrdine has made its
appearance in many silk worm nurseries
OF the department. Now the nauscdrdine
is due solely 10 the development of
bOtrytis bdssldnd in the body of the silk
worm. Is there not, he asks, more than
fortuitOus coincidence between this
appearance OF the muscdrdine and the
epidemic development of the tomato
disease? 1t Is possible, he suggests,
that sulphur applied in time, or sui
phurOus fumigations, would succeed in
arresting the disease, since means have
always been successful in analogous
cases, as in the oidium of the vine,
peach mildew, etc.