TRANSACTIONS OF SECTION G. 805 



the diameter of the tube. That the maudril is not requii-ed in the manufacture is 

 proved by stoppino- the action of the rolls while the bar is passing- through them, 

 and breaking oif the bar where the hollow is just commencing to form; the metal 

 inside is foiind to be crystalUne and bright, as before being cut there is a vacuum 

 within the hollow, no air, of course, entering during the process of manufacture. 



Specimens of tubes made out of Siemens open-hearth steel, which material is 

 specially suitable for the purpose, were exhibited at the meeting ; these show how 

 the tube in the centre commences by a fracture of the metal, which widens out, and 

 also the twist of the fibre having the appearance of a rope, which assists in giving 

 the tubes their great toughness and resisting po^"^ er. 



2. Gaseous Fuel} By J. Emerson Dowson, M.Inst.G.E. 



At the York Meeting of the Association in 1881 the author explained an appa- 

 ratus for making cheap heating-gas by passing steam and air through incandescent 

 fuel. Since then the apparatus has been considerably improved, and the gas made 

 in it has been much used, not only for driving engines but for heating in many 

 industrial processes. The composition of the gas necessarily depends somewhat on 

 the quality of the coal used and on tbe condition of the fire ; the average com- 

 position is much the same, whether the gas is made at the rate of 1,000 cubic feet 

 per hour in a small generator or at the rate of 15,000 cubic feet per hour in a 

 large one. In 1881 it was necessary for gas engines to use five volumes of this 

 generator gas for one of ordinary lighting-gas to develop the same power : since 

 then some important modifications have been made in the Otto engines, and it is 

 now necessary to use only four volumes. In 1881 only one engine of -i^ horse-power 

 had been worked with the author's gas, but since then a large number of engines 

 have been worked -with it, one indicating over 80 horse-power. For more than four 

 years Messrs. Orossley, the English makers of the Otto engines, have used this gas 

 exclusively at their works for an average power of 150 horse-power, and after a care- 

 ful trial extending over thirty-five weeks they have found that the fuel consumption 

 was only I'ci lb. per indicated horse-power per hour. At these large works there 

 is no chimney except for the blacksmiths' shop. Returns sent by eleven users of 

 Otto engines working regidarly in difi'erent places with the author's gas, and aver- 

 aging 35 horse-power each, show an average fuel consumption of about 1'3 lb. per 

 indicated horse-power per hour, which is less than half that required for tbe best 

 steam engines of equal power. The resvilts of other tests are given, and, seeing that 

 all have been obtained under practical working conditions, the record is certainly 

 satisfactory. Many letters have also been received testifying to the ease with 

 which the gas plant can be managed. 



The author considers himself justified in saying that gas-power is now fairly 

 launched in competition with steam-power, and he thinks with the late Professor 

 Fleeming Jenkin that eventually tbe former will to a great extent supersede the 

 latter. The author also thinks it tolerably sure that even better results than those 

 already recorded will be obtained when an engine is really designed to give the 

 best effect with generator gas. It is well known that in the Otto engines each new 

 charge of gas is diluted with a portion of the products of combustion from the 

 previous charge, and this answers very well for ordinary lighting-gas. But as 

 generator gas, such as the author's, has only about one-fourth the explosive power 

 of the other gas, it is a disadvantage to dilute it with products of combustion, and 

 he feels confident that sooner or later makers of engines will find it expedient to 

 design all engines of large power specially for cheap generator gas. The best fuel 

 to use for making the gas is anthracite, as it does not yield tar or other condensable 

 products, and does not cake in the generator. Ordinary gas-coke can also be used 

 with certain precautions. 



Several instances are given of the use of this gas for heating of various kinds. 

 At the Gloucester County Asylum it has been used daily for about five years. 

 All the kitchen-work for the staff and inmates is done with it, and there is no 



' Printed in extenso in Scientific Nervs, Sept. 1888. Also by the author. 



