TRANSACTIONS OF SECTION G. 485 



type superheated-steam engine, and the first firm to put this type of engine 

 on the market was Messrs. R. Wolf, of Magdeburg, Germany. Wolf engines are 

 running very successfully all over the world. The first English firm to manu- 

 facture engines of this type was Messrs. Richard Garrett and Sons, Limited, of 

 Leiston, and while retaining the same principles, they have produced an engine 

 in accordance with the best English practice. The overtype superheated-steam 

 engine consists of a special tubular boiler with the engine mounted on the top of 

 it, the boiler forming the foundation or bed-plate for the engine. A super- 

 heater is placed in the smokebox and forms an integral part of the plant, as also 

 do the air pump, condenser, &c, when such are fitted. The result of this 

 arrangement is that steam-pipe losses are reduced to a minimum and the full 

 value of the superheated steam can be employed. The cylinders can also be 

 jacketed with high-pressure steam from the boiler without any loss due to drains 

 or steam traps, as the cylinder casing forms a portion of the steam space of the 

 boiler. The boiler and the superheater are carefully designed as regards their 

 heating surfaces to give the highest efficiency. Particulars of exhaustive trials 

 work were given and comparisons drawn between these and those obtained with 

 a consumption of 1"21 lb. of steam coal per hour. Detailed description of the 

 ' Garrett ' engine giving full particulars of its construction was also given, with 

 drawings and photographs showing actual installations of some of these engines 

 in various types of factories. Particulars of actual results obtained in regular 

 work were given and comparisons drawn between these and those obtained with 

 other types of prime mover. The relative importance of the different items 

 which go to make up the cost of power in a factory was discussed, with especial 

 reference to that of reliability. 



2. Suction-Gas Engines and Producers. By W. A. Tookey. 



Notwithstanding that during the last ten years or so a very large number of 

 suction-gas plants have been installed in all quarters of the globe with satisfac- 

 tion to purchasers, as is evidenced by the increasing demand for these simple and 

 economical apparatus, it is a fact that figures recording the actual performances 

 with regard to fuel consumption, cost of maintenance, cost of repair, &c, are 

 difficult to obtain. Yet in order properly to appreciate the claims advanced by 

 the makers of gas engines and gas producers it is very necessary that such 

 records should be available, so that comparisons may be made with competing 

 types of motive-power generators, and more particularly those which, according 

 to test figures, would appear to compete very keenly, if not, indeed, to surpass, 

 gas power-plants in reliable and economical working. 



The author has collected from his own tests and those available from various 

 sources, representative performances of suction-gas plants of various sizes when 

 under test, not only when the power can be determined by means of some form 

 of brake dynamometer, but when generating electric current — so taking into 

 account the efficiency of the combined gas-electric set — and also when raising 

 water under different ' heads,' indicating the comparison between fuel consumed 

 and foot-pounds of work performed in such circumstances. 



However, inasmuch as ' test ' figures are usually obtained under what must be 

 admitted to be abnormal conditions — no account being taken of standby losses, 

 wastage of coal in charging, in removal of ashes, &c, the engine and producer 

 being worked at a constant and regular output for but a limited number of 

 hours— further figures were presented which enable the average performances 

 of suction-gas plants of moderate power to be noted. These figures have been 

 compiled from the statements of factory owners in Great Britain and in 

 European countries. They take into account the variations of consumption due 

 to the different grades of fuel used ; they reflect the influence of variations of 

 output, of load fluctuation, of length of standby periods, as well as the effect 

 of the variation in the human element in maintaining or otherwise those con- 

 ditions which make for the best gas-making and lowest consumption of fuel per 

 unit of power delivered. 



Mention was made of the recorded performances of suction-gas engines and 

 plants with regard to non-stop runs, as in information of this character it is 

 possible to realise how reliable are these installations and what little attention 



