The Kingston and Dalkey Railway — starting the train. Source: Illustrated London News 1844. Based on sketches by James Mahony. [Click on the image to produce a larger picture.]
Article beneath the engraving and on the following page
Atmospheric propulsion on railways is now an accomplished fact. Several preliminary trials have been made on the line we are about to describe, and very shortly the establishment will be in full operation.
The scene of this triumph of science is one line of the train laid down for the purpose of conveying granite from the quarries of Dalkey for the construction of the magnificent harbour at Kingstown, and the Dublin and Kingstown Railway Company having been empowered by their Act of Incorporation in 1851, to purchase the road, on the completion of the harbour works, with the consent of the Commissioners and of the Lord Lieutenant of Ireland, they opened a negotiation for the purchase of one half the road — or a single line — and the necessary consent having been obtained, the purchase was made, and the works were commenced.
It will scarcely be necessary to describe the general principles of the Atmospheric Railway; but there are some details connected with its practical application which it may be requisite to enter into, as tin applicability of the system depends principally on the mode of keeping the pipe air-tight. This explanation we quote from No. 10 of the Artisan, a work we conscientiously commended to our readers at its outset, and each succeeding Number has tended to raise this periodical in our estimation: it is at once sound and popular, elaborate and economical:—
In the Atmospheric Railway, a pipe of about twelve inches diameter is laid between the rails on which the carriages run; this pipe is exhausted at one end by an air-pump: a travelling piston is forced along it by the pressure of the atmosphere; and a rod, or plate, fit iron, connecting the piston with the carriages, traverses a slit on the top of the pipe. The great difficulty to be overcome was to cover this slit with a substance which would be air-tight, and yet would permit the connecting-rod to pass without offering much obstruction. The plan adopted by Messrs. Clegg and Saiuuda, the projectors of the system is improved, will be best understood by reference to the accompanying diagrams.
Figures 1 and 2 from the original article. [Click on images to enlarge them.]
Fig. 1 represents a vertical section of the pipe. The opening at the top is covered by a continuous valve G, extending the whole length of the pipe. It in formed of leather riveted between two iron plates. The upper plate is wider than the slit, and prevents the leather from being pressed in by the pressure of the atmosphere; the lower plate just fits the slit, and is curved to the shape of the pipe. One edge of the leather is fastened to a longitudinal rib, cast along the opening ind forms a hinge, as on a common pump valve. The other edge of the valve, when it covers the opening, forms, with a ridge cast on the pipe, a channel or trough, on its whole extent, a section of which is shown at F, fig. 2. This trough is filled with a composition of bees-wax and tallow, which, when melted and cooled, adheres to the side of the valve, and keeps it air-tight. As the travelling piston is forced along the pipe, one side of the valve is raised by four small wheels fixed behind the piston, so as to admit the connecting rod C to pass, as represented in fig. 1. The opening thus made also admits the air to act against the piston. The rupture thus made in the composition of wax and tallow is cemented again, before the train passes, in the following manner: — A steel wheel R (fig. 2), regulated by a spring, is attached to the carriage, and presses down the valve immediately after the connecting arm has forced it open, and a copper heater N, about five feet long, filled with burning charcoal, passes over the composition and melts it, thus leaving tne valve air-tight as before, and ready for the next train. A protecting cover, 1, formed of thin plates of iron about five feet long, and hinged with leather, is placed over the valve, to protect it from rain or dust. It is contemplated to have each pipe about three miles long, with a stationary engine for each length of piping to exhaust the air; and an arrangement is made by means of whicn the piston, as it approaches the end of the pipe, opens a valve which admits it into the next length of piping, so that the train may proceed from one to the other without stopping.
It is evident that as the tractive force is derived entirely from the pressure of the atmosphere on the piston, its amount will depend on the area of the piston, and on the extent to which the exhaustion of the air can be carried by the air-pump. It must also he evident that the difficulty of keeping the pipe air-tight will increase with its length, and with the pressure obtained. The Vacuum-pipe on the branch of the Birmingham, Bristol, and Thames Junction Railway, where the atmospheric system has been in operation for more than three years, is only nine inches internal diameter, and but half smile long. It is on an incline of part 1 in 120, and part 1 in ll.;. A vacuum, equal in some instances to a column of mercury 20 1/2 [?] inches high, has been obtained, and loads of 13 tons have been propelled at a speed of 20 miles an hour. On the Dalkey branch of the Dublin and Kingstown Railway, the pipe is 15 inches in diameter, and its length, so far as it has been tried, is one mile and a quarter. The average incline is 1 in 100; the exhaustion has been extended to 22 1/2 inches of mercury, and three carriages loaded with passengers have been propelled up the incline at a speed exceeding 40 miles an hour.
A stationary engine of 110 horse power would, it is stated, be adequate to exhaust a pipe of 18 inches diameter 2 1/2 miles long, in four minutes, and trains might be started each way every quarter of an hour, and convey daily 5000 tons.
In point of safety, the atmospheric plan seems far preferable to the locomotive. No collision of trains could take place whilst travelling on the rails. The only possibility of such accidents occurring would he at the junctions of the pipe, and by nothing abort of wilful negligence could they happen even there.
We have next to compare the pneumatic principle of traction with that by a rope, to which plan it bears the nearest resemblance. In working effect, however, the rope of air far surpasses the rope of hemp or iron.
It results from the consideration we have bestowed on the atmospheric railway, that, making allowance for the exaggerated statements of the projectors, and founding our estimate chiedy upon what has been actually accomplished, it is capable of being applied so as to afford a cheaper, safer, and a more convenient mode of conveyance, than locomotive railways.
Our engravings have been executed from sketches by James Mahony, Esq. They show—1. The Starting of the Train; 2, The Kingstown Station-house and Club-house. To the left of the view is seen the handsome monument raised by the loyal Irish, to commemorate the landing of George the Fourth.
“The Kingston and Dalkey Railway.” Illustrated London News. 48 (6 January 1844): 16-17. Hathi Trust Digital Library version of a copy in the University of Michigan Library. Web. 24 December 2015.
Last modified 24 December 2015