20 Alec Wihon on 



reversible, and revolving at moderate speed. With twin engines 

 of this class they drive the wing screws, and when the steam has 

 done all it can under these conditions, — when, in an ordinary 

 steamer, it is ready to pass to the condenser, — it enters a third 

 engine, the low pressure turbine, and there drives the rotor 

 before escaping to the condenser. 



The " Lmirentic " was the first large l)oat l)uilt with this com- 

 bination of reciprocating engines and low i)ressure turbine. This 

 boat was used as an experimental model, so far as her engines 

 were concerned, preparatory to deciding on the machinery for the 

 Olymjnc." She had a sister ship, identically the same except for 

 her engine arrangements. The results were so enormously in 

 favour of the " Lmirentic " that the combination has become, for 

 the present, a standard pattern, so to call it, which the firm uses 

 in its larger l)oats. In the case of the "Olympic " this method 

 of using the exhaust steam supplies a third propeller with no 

 less than 16,000 H.P., most of which would have been wasted 

 if the low iiressure turbine were not known. 



It will be noticed that the entire work of the turbine of a 

 boat thus fitted is done beloiv atmospheric jjressiu-e, Parson's 

 invention enabling the modei'n naval architect to recover thousands 

 of hoi'se power out of mere emptiness. The high pressure 

 turbine is a very wonderful invention, but the low pressure 

 one seems even moi-e astonishing in its capabilities of mechanical 

 economy. 



The whole engine is built up in the works exactly as it will 

 be on board ship, until it is practically ready for steam to be 

 turned on. It is then slowly driven round by a small motor to 

 make certain that everything is properly in its place and free to 

 move, and then the whole structure is dismantled and sent down, 

 beginning with the bed ])lates, to the big crane to be lifted on 

 board. 



Figure VII shows a funnel being lifted on board the liner. 

 This crane is capable of lifting a weight of 150 tons to a height 

 of ]. 50 feet and to a distance of 57 feet from the edge of the 



