OEDINARY OSCILLATING PADDLE-WHEEL ENGINES. 25 



same time sucli a rate of speed maintained as to enable lier 

 to hold her own with her newer rivals. 



This, then, was the problem to be solved. 



Fi'om tlio outset it appeared that, independently of the 

 boiler, it would bo necessary for economy's sake to retain as 

 much of the existing macldnery as possible; and to do this 

 it appeared necessary to keep one of the existing cylinders 

 as the low-pressure cylinder of the now compound arrange- 

 ment • for had it been attempted to fit a larger low-pressure 

 cylinder, it would pfa,ctica]ly have condemned the whole 

 ontTiiio. The old cylinders wore, as 1 have said, 66 inches 

 diameter x 72 inches stroke, and developed 1,600 indicated 

 horse power; and to have got this power out of a compound 

 enri-iiio witli the same stroke would have necessitated cylin- 

 ders 48 inches and 86 inches diameter respectively, which by 

 reason of want of space was out of tho question. It therefore 

 became necessary to so proportion the new high-pressure 

 cylinder as to obtain the maximum power possible out of the 

 old 66-inch low-pressure cylinder which it was proposed to 

 retain. 



Now those of you who are familiar with tho construction 

 of an oscillating engine, and have entertained the idea of 

 compounding it, will agree with me that the first difficulty 

 which presents itself is how to got tlio stoiun out of tho 

 high-pressure cylinder into the low-pressure cylinder, — the 

 exhaust trunnion of the former being amidships, and the 

 steam trunnion of the latter being at tho ship's side. 



I confess that here at the outset was a problem that fairly 

 pnz/dod me, and for some time I could not discover any suit- 

 able means of getting over it. 



Wo all enjoy a strcjke of luck when it falls in our way, 

 and after mentally turning the engines inside out and up- 

 side down, I experienced this pleasure whilst pondering over 



