TRANSACTIONS OF SECTION G. 759 



the successive tubes and piers being eflFected froui within the tubes already laid, 

 which are in direct railway communication witli the shore. The author pointed 

 out that the necessity which drives us to the use of water-tight tubes for our pur- 

 pose is incidentally attended by enormous advantages, enabling us to build our 

 structures in the ordinary shipbuilding and engineering establishments of the 

 country, and tow them to their places, thus avoiding the cost, difficulty, delay, and 

 danger of doing our construction work at the bottom of the sea. The piers -will 

 stand upon and be pressed into the bottom where the consistency of the bottom 

 admits of this, but the tubes themselves will not lie upon the sea-bed, but will 

 stretch from pier to pier, striding over the minor inequalities of the bottom, and 

 allowing the tidal water to pass both below and above it. The estimated cost of 

 the work (which depends somewhat upon details to be determined by close survey) 

 is from twelve to fifteen millions sterling for the whole distance between England 

 and France, which the author regarded as small by comparison of the cost of such 

 bridges as the Forth Bridge, which cost over three millions sterling for bridging 

 5,700 feet of water, the tubular railway being 120,000 feet long. The ventilation 

 will be an easy matter, seeing that all the trains passing through either tube will 

 move in one direction, and act somewhat as pistons for forcing out air, the effect 

 being increased by throwing out wings from the train so as to make it fit the 

 interior of the tube more approximately. The author intimated that electric 

 engines will probably be used, but, if not, and if further ventilation be needed, any 

 one or more of the piers can be fitted with ventilating machinery for forcing the 

 deteriorated air out through suitable chambers and non-return valves into the sea. 

 As regards the question of national security, the author pointed out that the oppo- 

 sition to the Channel Tunnel had arisen from the fact that it provided a subter- 

 ranean road, inaccessible to, and therefore indestructible by, the Navy ; whereas 

 the tubular railway could be pierced, and have the sea admitted to it, either by 

 gun-fire at the shore ends, or by dynamite or torpedoes at every point of its length. 

 He concluded by stating that a great many members of Parliament, who always 

 strongly oppose the Channel Tunnel, are quite in favour of his system, and among 

 these are several of such great influence that he has little fear of his Bill beino- 

 successfully opposed in either House of Parliament. 



2. Petroleum Oil-engines. Bij Professor William Robinson, M.E., 

 Assoc. M.Inst.G.E. 



The use of ordinary petroleum oil at once as fuel and working agent in the 

 internal combustion engine has extended rapidly since the successful introduction 

 of the oil engine by ^Messrs. Priestman Brothers in 1888. 



Hitherto, for large engines above 40 horse-power, the heavy intermediate oils 

 have been converted into gas by means of a yas-producer, and this oil-gas takes 

 the place of coal-gas in the ordinary gas-engine cylinder. Now, instead of the gas- 

 producer we find in one class of oil-enfjine a retort, spiral coil of tubing or other 

 vaporiser, in which the oil is heated and converted into vapour by a lamp or oil- 

 burner. A mixture of this vapour and air is drawn into the cylinder, and the 

 charge is compressed before ignition — the cycle of operations in the engine cylinder 

 being usually that of Beau de Rochas, as in the well-known Otto gas-engine. For 

 instance, Messrs. Crossley Brothers are making an oil-engine in which a lamp 

 performs the twofold function ; first, to heat and evaporate the oil in a retort, and 

 second, to heat the tube-igniter, which is timed by a A'alve similar to that in their 

 gas-engines. This lamp has a separate supply of oil given to it by a pump and a 

 current of air from an air-pump. The details of this and several other attempts 

 at workable engines of this class are still in the transition stage. 



Again, in the petroleum spirit-engine there are many air-carburetting devices to 

 evaporate the highly volatile hydro-carbons which make up the lighter products of 

 petroleum, such as benzoline and gasoline. The terrible danger and risk in the 

 storage of these light oils prohibit their common use for this purpose. 



In the Priestman Spray-maker and Vaporiser we have a neat and practical corn- 



