Fig. 48.—Gurney’s Steam-Carriage.

[Large scale image] (241 kB).

In the sketch ([Fig. 48]) this boiler is seen at the right. It was composed of bent ◁-shaped tubes, a a, connected to two cylinders, b b, the upper one of which was a steam-chamber. Vertical tubes connected these two chambers, and permitted a complete and regular circulation of the water. A separate reservoir, called a separator, d, was connected with these chambers by pipes, as shown. From the top of this separator a steam-pipe, e e e, conveyed steam to the engine-cylinders at f. The cranks, g, on the rear axle were turned by the engines, and the eccentric, h, on the axle drove the valve-gearing and the valve, i. The link, k l, being moved by a line, l l, led from the driver’s seat, the carriage was started, stopped, or reversed, by throwing the upper end of the link into gear with the valve-stem, by setting the link midway between its upper and lower positions, or by raising it until the lower end, coming into action on the valve-stem, produced a reverse motion of the valve. The pin on which this link vibrated is seen at the centre of its elliptical strap. The throttle-valve, o, by which the supply of steam to the engine was adjusted, was worked by the lever, n. The exhaust-pipe, p, led to the tank, q, and the uncondensed vapor passed to the chimney, s s, by the pipe, r r. The force-pump, u, taking feed-water from the tank, t, supplied it to the boiler by the pipe, x x x, which, en route, was coiled up to form a “heater” directly above the boiler. The supply was regulated by the cock, y. The attendant had a seat at z. A blast-apparatus, 1, was driven by an independent engine, 2 3, and produced a forced blast, which was led to the boiler-furnace through the air-duct, 5 5; 4 4 represents the steam-pipe to the little blowing-engine. The steering-wheel, 6, was directed by a lever, 7, and the change of direction of the perch, 8, which turned about a king-bolt at 9, gave the desired direction to the forward wheels and to the carriage.

This seems to have been one of the best designs brought out at that time. The boiler, built to carry 70 pounds, was safe and strong, and was tested up to 800 pounds pressure. A forced draught was provided. The engines were well placed, and of good design. The valve was arranged to work the steam with expansion from half-stroke. The feed-water was heated, and the steam slightly superheated. The boiler here used has been since reproduced under new names by later inventors, and is still used with satisfactory results. Modifications of the “pipe-boiler” were made by several other makers of steam-carriages also. Anderson & James made their boilers of lap-welded iron tubes of one inch internal diameter and one-fifth inch thick, and claimed for them perfect safety. Such tubes should have sufficient strength to sustain a pressure of 20,000 pounds per square inch. If made of such good iron as the makers claimed to have put into them, “which worked like lead,” they would, as was also claimed, when ruptured, open by tearing, and discharge their contents without producing the usual disastrous consequences of boiler explosions.

The primary principle of the sectional boiler was then well understood. The boilers of Ogle & Summers were made up of pairs of upright tubes, set one within the other, the intervening space being filled with water and steam, and the flame passing through the inner and around the outer tube of each pair.

One of the engines of Sir James Anderson and W. H. James was built in 1829. It had two 31∕2-inch steam-cylinders, driving the rear wheels independently. In James’s earlier plan of 1824-’25, a pair of cylinders was attached to each of the two halves into which the rear axle was divided, and were arranged to drive cranks set at right-angles with each other. The later machine weighed 3 tons, and carried 15 passengers, on a rough graveled road across the Epping Forest, at the rate of from 12 to 15 miles per hour. Steam was carried at 300 pounds. Several tubes gave way in the welds, but the carriage returned, carrying 24 passengers at the rate of 7 miles per hour. On a later trial, with new boilers, the carriage again made 15 miles per hour. It was, however, subject to frequent accidents, and was finally withdrawn.

Walter Hancock was the most successful and persevering of all those who attempted the introduction of steam on the common road. He had, in 1827, patented a boiler of such peculiar form, that it deserves description. It consisted of a collection of flat chambers, of which the walls were of boiler-plate. These chambers were arranged side by side, and connected laterally by tubes and stays, and all were connected by short vertical tubes to a horizontal large pipe placed across the top of the boiler-casing, and serving as a steam-drum or separator. This earliest of “sheet flue-boilers” did excellent service on Hancock’s steam-carriages, where experience showed that there was little or no danger of disruptive explosions.

Hancock’s first steam-carriage was mounted on three wheels, the leading-wheel arranged to swivel on a king-bolt, and driven by a pair of oscillating cylinders connected with its axle, which was “cranked” for the purpose. The engines turned with the steering-wheel. This carriage was by no means satisfactory, but it was used for a long time, and traveled many hundreds of miles without once failing to do the work assigned it.