ously obstructed; the special form illustrated was,
therefore, carried into execution. The bridge, as will be seen from Figs.
1, 2, 3, and 7, consists of two main arched girders, with two vertical
sides in lattice work; these arches spring below the level of the roadway
and rise to a considerable height above it, in the center. The horizontal
girders carrying the roadway, are connected to the arches by verticals of
the form and section shown in the drawings. The longitudinal girders are
of double trellis, as will be seen by reference to Figs. 1, 12, and 16.
The following are the principal dimensions of the bridge:

Ft. In.
Clear opening between abutments 291 4
Rise of arch 32 93/4
Width of bridge 37 43/4
Depth of arched girders 4 7

[Illustration: BRIDGE OVER THE RIVER ADIGE, AT VERONA.]

The arched girders are connected together, in the central portion, by a
system of diagonal bracing, as is shown on Figs. 2 and 7. The carriage
road on the platform consists of buckled plates resting on transverse
girders spaced 6 ft. 6 in. apart, and covered with road metal, and for
the sidewalks checkered plates are used. The ironwork in the bridge
weighs 400 tons, and cost 8,400 _l._; the abutments cost 3,600_l._,
making the total outlay on the structure 12,000_l_. The bridge was
tested by a uniformly distributed load of 82 lb. per sq. ft., and under
this stress the arched girders deflected 1.06 in. The horizontal and
vertical oscillation of the bridge, which were carefully observed and
graphically recorded by special instruments, were very slight. The
engineer of the work was Mr. G.B. Biadego, of Genoa.--_Engineering_.

* * * * *

PUMPING MACHINERY.

[Footnote: A paper read at the Montreal Meeting of the British
Association.]

By E.D. LEAVITT, JR., Cambridgeport, Mass.

MINE PUMPING MACHINERY.

One of the earliest steam engines, of any size, introduced into America,
was erected about the year 1763, at the Schuylkill copper mine, situated
upon the Passaic River, in New Jersey. All its principal parts were
imported from England; and a Mr. Hornblower (the son, it is believed, of
the well known engineer of that name) came to this country for the
purpose of putting up and running this engine.

At the time when the manufacture of the engines for the Philadelphia
Water Works was commenc