496 KEPOET— 1881. 



that tlie danger which at one time existed of the collapse of these 

 fire-flues has been entirely removed, by his application of circum- 

 ferential bands. Now-a-days there are, as we know, modifications of Sir 

 William Fairbairn's bands ; but by means of his bands, or by modifica- 

 tions thereof, all internally flued boilers are so strengthened that the 

 risk of a collapse of the flue is at an end. Boilers of this kind are well 

 calculated to furnish, and commonly do furnish, steam of from 40 lbs. to 

 80 lbs. pressure above atmosphere ; the piston-speed is now very gene- 

 rally 400 feet or more, so that, notwithstanding that there is usually a 

 liberal expansion, the mean pressure upon the piston is greater, and 

 this, coupled with the increased piston-speed, enables much more power 

 to be obtained from a given size of cylinder than was formerly ob- 

 tainable. The revolutions of the engine now are as many as from 60 to 

 200 per minute, and thus, with far lighter fly-wheels, uniformity of rota- 

 tion is much more nearly attained. Moreover, engines are now self-con- 

 tained, and no longer depend upon the foundation for the connection of 

 their parts. In many cases the condensing is effected either by surface 

 condensers, or, where there is not an ample supply of water, the con- 

 densation is in a few instances effected by the evaporative condensei* — 

 a condenser which, I am sorry to say, is not generally known, and is 

 therefore but seldom used, although between thirty and forty years 

 have elapsed since its first introduction. Notwithstanding the length 

 of time during which the evaporative condenser has been known to 

 some engineers, it is a common thing to hear persons say, when you ask 

 them if they are using a condensing engine, ' I cannot use it, I have 

 not water enough ' — a very sufficient answer, indeed, if an injection 

 condenser or an ordinary surface condenser constituted the sole means 

 by which a vacuous condition might be obtained, but a very insufficient 

 answer having regard to the existence of the evaporative condenser, as 

 by its means whenever there is water enough for the feed of a non- 

 condensing engine, there is enough to condense the exhaust steam, 

 and to produce a good vacuum. The evaporative condenser simply 

 consists of a sei'ies of pipes, in which is the steam to be condensed, 

 and over which the water is allowed to fall in a continuous rain. By this 

 arrangement there is evaporated, from the outside of the condenser, a 

 weight of water, which goes away in a cloud of vapour and is nearly 

 equal to the weight of steam which is condensed, and is returned as feed 

 water into the boiler. The same water is pumped up and used outside the 

 condenser over and over again, needing no more to supply the waste than 

 would be needed as feed water, and as the condenser acts by evaporation 

 its effect is practically as good whether the external water be warm or cold. 

 Although this condenser has, as I have said, been in use for thirty or 

 forty years, there are still to be seen engines, working without condensa- 

 tion at all, or with waterworks water, purchased at a great cost, and to 

 the detriment of other consumers who want it for ordinary domestic 

 purposes ; or large condensing ponds are used in which the injection 

 water is stored, to be worked over and over again, and frequently 

 (especially towards the end of the week) in so tepid a state as to be unfit 

 for its purpose. The governing is now done by means of quick-running 

 governors, which have power enough in them to raise, not merely the 

 pendulum-balls, which are small, but a very heavy weight, and in 

 this way the governor is extremely effective. I propose to say no more 

 — looking at the magnitude of the whole of my subject — upon the engine 



