When under these circumstances the tube has been heated to a high temperature in a convenient fire box, the water which has been pumped into it, by a feed pump fastened to one of its extremities, is instantly changed into steam and escapes at the other end at a pressure and in a state of dryness depending on the working conditions of the apparatus. The ingenious and really original and novel idea in this invention is this flattened tube, which constitutes an actual capillary boiler inside of which the water squeezed in between its walls cannot assume its spheroidal state, and the formation of drops becomes absolutely impossible. There exists no longer a residue of hot water, nor are water gauges, safety valves, or any other of those numerous accessories required which make all steam boilers so complicated and which augment considerably their cost.
It also becomes unnecessary to connect the joint from which the steam escapes by means of a valve with the motor for which the steam is to be used. If the supply of steam is to be stopped, this can be done by simply suppressing the supply of water, i.e., by emptying the boiler.
The regular working is assured by the quantity of heat contained in the heated iron tube, to which, for this purpose, an intentionally great thickness has been given, and it is this heat of the iron which replaces the heat furnished by the hot water in the steam generators with boiler tubes. From the above it will be easy to understand the general arrangement of the new steam generator, when connected with its motor. This motor works a small intermitting pump, which supplies the capillary boiler with water, according to the quantity consumed. The machine is started by means of a small special pump worked by hand.
Whenever the velocity of the motor tends to increase, a centrifugal regulator placed upon the motor reduces the action of the pump and, consequently, the supply of water to the tube, thus checking the velocity of the machine. If the velocity tends to slacken, the inverse process is employed. In order to stop the machine, it suffices to turn off the water furnished by the pump by means of a three-way cock, and to send the water back to the reservoir of supply. The boiler can be emptied in less than a second, and the motor stops in consequence of being deprived of motive power.
The whole is marvelously simple, and creates astonishment and admiration in the mind of even the most skeptical persons who see the apparatus.
The boiler of the one horse power type weighs 33 kilogrammes. It consists of an iron tube having a length of 2 meters and a height of 10.5 centimeters after it has been flattened; the total heating surface thus obtained being 48 square centimeters. The power of vaporization amounts to 20 kilogrammes of water per hour, while the quantity of coal consumed during the same period amounts to only 4 kilogrammes, which is comparatively little for a boiler of so small a power.
Fig. 2.—TRICYCLE PROPELLED BY A SERPOLLET BOILER
Fig. 2 shows the first model of a tricycle constructed by Messrs. Serpollet as an application of their boiler for locomotion. The writer has seen the working of this apparatus, and consequently is able to give some data. The total weight of the machine is 185 kilogrammes, or about 250 kilogrammes when mounted by a person. The boiler is placed behind the tricycle, the motor is under the seat, inside of which is the water reservoir and the supply of coal. In the motor employed in the present case the feed pump is a constant supply pump, but by means of a directing lever turning around its own axis and acting upon a three-way cock, the water can be divided into two streams, the one emptying into the feeding reservoir, the other into the boiler. By varying the position of the cock, the power of the machine can be modified and its velocity regulated. The machine can be brought to a stop within less than two meters by means of the combined action of a brake and the complete suppression of water in the boiler. In order to start the machine, the water is sent into the tube by a little extra pump worked for a moment by the left hand of the cyclist when starting.
On July 25 some experiments were made before the Society of Civil Engineers with the tricycle above described, and on that occasion it traversed the Rue Girardon and the Rue de Norvino to Montmartre (streets in which the gradient rises to 15 centimeters per meter) with a velocity of three meters per second.