The illustration represents a multiple wire tester, constructed for the Trenton Iron and Steel Company by Riehle Bros., of Philadelphia. It consists of a weighing mechanism (seen on the left, with a capacity of 4,000 pounds), two single or alternating pumps, a hydraulic jack, a patented three-way valve, and a rising and falling accumulator.

The weighing end of the machine, placed horizontally and secured by bolts to a foundation, is accurate, and will weigh the strain on one to six wires at a time. It is provided with self-adjusting grips to take in wires from No. 10 to No. 16, and hold them firmly. It can be adapted to take in a larger or smaller range of numbers when desired. There is a set of gripping appliances at both ends, and in the present instance they are 90 feet apart—one set at the scale end, and the other secured to head of piston. The jack is 5 feet in length, and lined with brass; its outside diameter is 3½ inches; its inside diameter, 2¼ inches. Like the scale end, it is firmly bolted down to its foundations.

The plunger has a stroke of 4 feet. It is supported and guided by three guides, the top one being a straight tube running on turned rollers. A three-way valve controls the movements of the jack and accumulator, and supplies water to the jack by a lever. When the lever is raised, the water is forced into the larger area of the jack, causing the plunger to move backward and bring a strain on to the wires or other specimens; when the lever is lowered, the water in the larger area of the jack only returns to the reservoir of the pump (to be used again). Now, without changing the position of the lever, the plunger will return automatically, without weight or counterbalance, with a steady, smooth, and uniform motion.

The pump has a slow motion, 60 revolutions per minute. It has two single action pistons, and the valves are so simple and readily accessible that an ordinary mechanic can examine and repair, when necessary, in a short time. The accumulator is so arranged as to overflow when it comes to its maximum height. The machine can be adapted to stretching and straightening wires in lengths to a given amount.

The weight on the scale and that on the accumulator is made to correspond, so that wires of a certain number or size can be quickly tested in quantities under exactly the same conditions, with only the movement of the lever.