Scientific American Supplement, No. 717, September 28, 1889 | Page 2

Exposition gives us the occasion to publish, we thought we would
make a happy contrast by selecting a subject of a different kind, by
presenting to our readers Mr. Layraud's fine picture, which represents
the gigantic power hammer used at the St. Chamond Forges and Steel
Works in the construction of our naval guns. By the side of the
machinery gallery and the Eiffel tower this gigantic apparatus is well in
its place.
[Illustration: UNIVERSAL EXPOSITION--BEAUX ARTS--MARINE
IRON AND STEEL WORKS AT SAINT
CHAMOND--PRESENTATION OF A PIECE OF ORDNANCE
UNDER THE VERTICAL HAMMER.--PICTURE BY M. JOSEPH
LAYRAUD.]
The following is the technical description that has been given to us to
accompany our engraving: In an immense hall, measuring 260 ft. in
length by 98 ft. in width, a gang of workmen has just taken from the
furnace a 90 ton ingot for a large gun for an armor-clad vessel. The
piece is carried by a steam crane of 140 tons power, and the men
grouped at the maneuvering levers are directing this incandescent mass
under the power hammer which is to shape it. This hammer, whose
huge dimensions allow it to take in the object treated, is one of the
largest in existence. Its striking mass is capable of reaching 100 tons,
and the height of the fall is 16 ft. To the left of the hammer is seen a
workman getting ready to set it in motion. It takes but one man to
maneuver this apparatus, and this is one of the characteristic features of
its construction.
The beginning of this hammer's operation, as well as the operations of
the forge itself, which contains three other hammers of less power,
dates back to 1879. It is with this great hammer that the largest cannons
of the naval artillery--those of 16 inches--have been made (almost all of
which have been manufactured at St. Chamond), and those, too, of 14,
13, and 12 inches. This is the hammer, too, that, a few months ago, was
the first to be set at work on the huge 13 in. guns of new model, whose

length is no less than 52 ft. in the rough.
Let us add a few more figures to this account in order to emphasize the
importance of the installations which Mr. Layraud's picture recalls, and
which our great French industry has not hesitated to establish,
notwithstanding the great outlay that they necessitated. This huge
hammer required foundations extending to a depth of 32 ft., and the
amount of metal used in its construction was 2,640,000 pounds. The
cost of establishing the works with all the apparatus contained therein
was $400,000.--Le Monde Illustré.
* * * * *

FORGING A PROPELLER SHAFT.
During the recent visit of the Shah of Persia to England, he visited,
among other places, the great works of John Brown & Co., at Sheffield,
and witnessed the pressing of a propeller shaft for one of the large
ocean steamships. The operation is admirably illustrated in our
engraving, for which we are indebted to the Illustrated London News.
[Illustration: PROPELLER SHAFT BEING PRESSED AT MESSRS.
JOHN BROWN & CO.'S WORKS, SHEFFIELD.]
* * * * *

CRANK AND SCREW SHAFTS OF THE MERCANTILE
MARINE.[1]
By G. W. MANUEL.
[Footnote 1: A paper read before the Institute of Marine Engineers,
Stratford, 1889.]
Being asked to read a paper before your institute, I have chosen this
subject, as I think no part of the marine engine has given so much

trouble and anxiety to the seagoing engineer; and from the list of
shipping casualties in the daily papers, a large proportion seem due to
the shafting, causing loss to the shipowner, and in some instances
danger to the crew. My endeavor is to put some of the causes of these
casualties before you, also some of the remedies that have tended to
reduce their number. Several papers have been read on this subject,
chiefly of a theoretical description, dealing with the calculations
relating to the twisting and bending moments, effects of the angles of
the cranks, and length of stroke--notably that read by Mr. Milton before
the Institute of Naval Architects in 1881. The only practical part of this
paper dealt with the possibility of the shafts getting out of line; and
regarding this contingency Dr. Kirk said that "if superintendent
engineers would only see that the bearings were kept in line, broken
crank and other shafts would not be so much heard of." Of course this
is one of those statements made in discussions of this kind, for what
purpose I fail to see, and as far as my own experience goes is
misleading; for having taken charge of steamers new from the builders'
hands, when it is at least expected that these shafts would be in line,