ATMOSPHERIC K.ULWAV. 



ATMOSPHERIC RAILWAY. 



70t 



grater than that mulling from the oooUot with copper. The corro- 

 ion of copper may be considerably retarded by fastening to it at 

 several poioU, pisoss ol cast or wrought iron, or of tine, when sulphu- 

 ratted hydrogen U likely to be present. Water containing bicarbonate 

 of Urn* will deposit the lime if placed in contact with one and copjwr, 

 the deposit taking place upon the copper : and when water of thi> 

 deseriptioa flow, through leaden pipe*, the carbonate of lime it deposited 

 at the colder joints (composed of an allay uf tin and lead), on the bran 

 cocks, and on any piece of iron or silver which may be introduced. 

 The incoarenience arising from the stoppage thus produced may be 

 obviated by the UM of a lateral pipe 6tted to the main at intervals, and 

 furnished with plugs of a metal likely to deposit the calcareous matter, 

 which can thus be withdrawn from the main. 



under eertain circumstances is affected by the action of the 

 ere ; for the potash and aoda employed in its manufacture are 

 *ible of being decomposed and removed by the moisture, or the 

 ** l n fc *fa*' < in it ; and according to Qmelin the decomposition takes 

 place with greater ease in proportion as the glass U richer in the above- 

 named alkalies, and the temperature of the moisture or water is higher. 

 Olass in which there U a deficiency of silica is exposed to this descrip- 

 tion of decay, which may often be distinctly perceived in window glow, 

 the alkali from which is gradually attracted (Knapp's 'Applied 

 Chemistry,' vol. ii. p. 8) by atmospheric moisture and washed away, 

 whilst a thin layer of silica or of silicate of lime remains upon the surface 

 and exhibits a play of prismatic colours. An analogous decomposition 

 takes place in the glass used in stables, in consequence of the ammo- 

 niacal gases ; and, according to Knapp, glass containing oxide of lead is 

 liable to blacken on exposure to air impregnated with sulphuretted 



The chemical changes produced in oleaginous and metallic pigments 

 by the gases contained in the atmosphere are subjects of the highest 

 importance to the decorative artist ; but as the examination of them 

 would extend this notice beyond the usual limits, the reader is referred 

 to the researches of M. Chevreul in the ' Mdmoires de 1' Academic dee 

 Sciences,' 1850 (voL nil). It may here, however, suffice to say that 

 M. Chevreul attributes the solidification of paints to the oils they 

 contain absorbing oxygen from the atmosphere, and states that the 

 driers act by facilitating the power of absorption. The various sub- 

 stances introduced to communicate colour appear to affect the rate of 

 absorption ; and the surfaces upon which the paints are applied, have 

 an influence independent of their mere capacity of taking up moisture. 

 The varieties in the rates of drying upon the several woods and metals 

 experimented upon by M. Chevreul, indicate some peculiar differences 

 in this respect, which have not hitherto been sufficiently examined. 



[The greater part of this article was read by our contributor, Mr. Oeo. 

 K. Hunu-11, at the ordinary general meeting of the Koyal Institute of 

 British Architects, June 5, 1854 ; and as the notice embraces a great 

 variety of substances used in construction, Mr. Burnell reprints it for 

 general information in preference to any abridgment.] 



ATMOSPHERIC RAILWAY. The history of failures constitutes 

 an important part of the history of science and practical art ; and, on 

 this ground, the atmospheric railway may suitably receive a little 

 notice here. The idea of producing motion by atmospheric pressure 

 was conceived by Papin, the well-known French engineer, nearly two 

 centuries since. After slumbering for more than a century, the 

 subject was successively taken up by Lewis, Medhunt, Vallance, and 

 Pinkus, and lastly by Clegg, in connection with Jacob Samuda. 

 Medhurst not only cherished the idea of locomotion by atmospheric 

 pressure, but devised many plans for iu accomplishment. One of 

 these plans related to the construction of on air-tight tunnel of suffi- 

 cient magnitude to admit the passage of carriages within it, running 

 upon iron rails, and propelled by air forced in behind them by 

 pumping machinery; the carriages being made so nearly to fit the 

 tunnel that the air thus forced in could not pass them, but must act upon 

 them as upon a piston. Another invented the use of a vacuum in front 

 of the piston, instead of compressed air behind it A third related to 

 the arrangement of carriages imttidt the tube, connected by mechanism 

 with the air-driven piston inside. In a fourth plan there was to 

 be a smaller tube between the two rails of an iron tramway. 

 Vallance's plan, made public in 1825, related to the conveyance of 

 nssMi(Miiii along a railway hud within an air-tight tunnel, which ho 

 proposed to construct either of cast-iron or of vitrified clay, resembling 

 common brickwork, but less permeable to air; but, knowing that 

 experiments had proved a very great loss of power to result from the 

 attempt to impel air through a long pipe, he proposed to set the 

 piston-carriage in motion solely by exhausting the tunnel in advance 

 of it, and suffering the full pi insure of the atmosphere to act upon its 

 rear. This plan, which was patented in 1823, was brought into expe- 

 rimental operation at Brighton upon a sufficiently Urge scale to prove 

 the possibility of so singular a mode of transport ; but, had there been 

 no other difficulties, the objections of the travelling public to trans- 

 mWon in a dark close tunnel would have proved sufficient to prevent 

 its general adoption. About the year 1885 the subject was revived 

 in enossnnsnos of a patent being taken out by Mr. Henry Pinkus, 

 an American gentleman rraiditiK in England, for an apparatus which 

 he called the Pneumatic Railway. This, as originally proposed, was 

 to eonsiet of. a cast-iron Uibe fmtu 30 to 40 inches internal diameter, 

 of an average thickness of three-quarters of an inch, and having a 



longitudinal slit or opening from one to two inches wide along what was, 



when laid in its proper position upon the railway, intended to be its 

 upper side ; this slit furnished on opening through whii-h the 

 mechanism of the piston inside the tube could be connected with that 

 of the carriages on the outside. Some time afterward*, Mr. Pinkim 

 made trial, on a piece of experimental railway laid down n. 

 Kensington Canal, of a tube much smaller in diameter, and differently 

 arranged ; but the experiment led to no immediate results. 



In 1840, Messrs. Clegg and Samuda arranged with the West London 

 Railway Company for the temporary use of a portion of their line near 

 Wormwood Scrubs, upon which they laid down about half a mil.- , f 

 railway, with a rising gradient of about 1 in 120 ; and notwithstanding 

 the defective arrangements, the results of the first trials showed a 

 maximum speed of 30 miles per hour with a load of 5 tons 9 cwt. in 

 one carriage, and of 22) miles per hour with a load of 11 tons 10 cwt. 

 in two carriages. This experiment was deemed so satisfactory, th.it 

 the directors of the Dublin and Kingstown Railway determirj 

 .i<|. .|>t the atmospheric mode of working upon a projected exten - 

 their line from Kingstown to Dalkey, the gradients and curves of \\ h > h 

 rendered it unsuitable for working by locomotive engines. This lino 

 was so for completed as to be ready for working in August, 1843. In 

 1844j the London and Croydon Railway Company obtained parlia- 

 mentary sanction to a plan for laying down a line of atmospheric 

 railway alongside of their locomotive line from London toCroy.l"ii. 

 and making on extension of the same from Croydon to Epsom. Alumt 

 the same time, and within a year or two afterwards, many other 

 atmospheric railway schemes were brought before the notice of Par- 

 liament, some of which were sanctioned by Acts. 



The result of these schemes has not borne out the expectations of 

 the projectors. The atmospheric system won tried on portion* of the 

 Croydon and the South Devon Railways; and after lengthened 

 trials, the costliness and the inconvenience of the system led to the 

 removal of the atmospheric apparatus from those railways. The only 

 line which was worked during a lengthened period was that of the 

 Kingstown and Dalkey Railway ; but even that was ultimately aban- 

 doned in favour of locomotive engines, when the line was extended to 

 Bray. 



As a record of a very ingenious though (commercially) unsuccessful 

 invention, we will briefly describe the arrangements of the Kingstown 

 and Dalkey Atmospheric Railway. In the subjoined cut, jiij. I repre- 

 sents a cross-section of the atmospheric tube with the valve closed, 

 and fij. 2 with the valve open for the passage of the connecting-bar 

 between the piston and the external carriage. The tube, formed of 

 cast-iron, in convenient lengths, flanged together, was laid in the 

 middle of the railway track, and firmly secured to sleepers imbedded 

 in the road. On the Dalkey line, which rose 71 feet in a distance of a 

 mile and three-quarters, a tube of about IS inches diameter was used. 

 Along the upper side of the tube was the continuous slit or opening, 

 at a, and on either side of it were vertical ribs or cheeks, b and c, cast 

 with the tube ; the space between these cheeks formed a trough when in 

 the valve lay secure from injury. The valve itself consisted of a 

 piece of strong leather, firmly enclosed between two pieces of iron. 

 The leather was on the side marked b, considerably wider than, the 

 tipper plate, and ite projecting edge was attached to the flat floor of 

 the valve-trough, at the base of the cheek 6, so as to form n continuous 

 hinge. The more perfectly to prevent the ingress of air, the opposite 

 or opening edge of the valve was, when closed as in Jig. 1, hermetically 

 sealed with a composition of wax and tallow, which filled the small 

 groove or space left between it and the cheek c. To protect the valve 

 more thoroughly, the trough was closed in with a sheet-iron COVIT it, 

 hinged with leather to the top of the check h, and shutting down 

 closely upon the top of the cheek e. The interior of the tube 

 was lined with a soft composition, which filled up all little irre- 

 gularities, and rendered the passage perfectly smooth and even. 

 The piston was attached to the fore end of a rod which is seen in 



Fig. 1. 



section at/ and which carried rollers so fixed as to lift up ;m<l open 

 the valve immediately afu-r the piston had passed, thus bringing it 

 into the position indicated in /</. 2. This position allowed room for 

 the passage of the connecting-bar c ; the iron cover d being previously 

 raised and held open by a coulter and a scries of wheels or friction- 

 rollers attached to the carriage. After the connecting-bar had passed, 

 a roller attached to the carriage pressed the valve down into its seat, 

 while a heater gliding along the mass of composition at its opening 



