THE KANSAS CITY BRIDGE. 85

First Tust.—Bar, 14 inches square, with welded loop at each end, length
5 feet between centres of loops. Four equal spaces of one foot each were laid
out on the central part of the bar. No perceptible extension was noted with a
strain of 10,000 lbs. per square inch, and but little with 20,000 Ibs. With a
total strain of 130,000 Ibs., equal to 57,777 lbs. per square inch, the length had
increased six inches, and the bar yielded by the opening of one of the welds ;
the four spaces, after the removal of the bar, measured respectively 1244,
1241, 12% and 13% inches; the last including a part of the broken weld.

Seconp Trst.—Bar 2 inches square, 9 feet long, with loop on one end and
nut on the other, extended by strain of 130,000 lbs. 1 inch, by 160,000 Ibs. 3
inches, by 176,000 Ibs. 42 inches, by 200,000 lbs. 8 inches, and by 221,000 lbs.
12 inches, when it broke about 18 inches from the nut, showing a fine fibre-like
fracture, the strain being 55,250 ibs. to each original inch of section ; but the
reduced section at the break was only 2.85 sq. inches, making the strain some-
what over 77,000 lbs. to the square inch. Five equal spaces of one foot each,
laid off on the bar before straining, measured after the break 133, 13%, 133%,
134 and 132 inches.

Tarp Test.—Bar 1% inches square, 38 feet long, and 3.0625 sq. inches,
under the following strain extended as given below :—

Total strain, 26,000 Ibs. 8,500 Ibs. to square inch. Extension, 1 inch.
ce 52,000 ce 17,000 “ ce ce 345 “ec
“ 78,000 “ 25,500 “ce “ce “ce 33 ce

No perceptible set after strain of 28,000 lbs. on the square inch.

A number of tests were made at the same time of iron of the same quality
manufacturing for the Dubuque bridge, with similar results. This iron is of
the kind known as Kloman’s mixture, manufactured at the Union Iron Mills,
Pittsburg, the ties and truss-rods being made of double-rolled, refined iron.
The bar broken in the second test was afterwards cut up, and three small pieces
were turned out of it, each having a reduced central diameter. These were
taken to the Fort Pitt Foundery, and tested in the lever machine belonging to
the U. S. Government ; two of these tore out of the clutches before breaking,
when the strains per square inch were respectively 62,760 Ibs. and 63,134 Ibs.