G.—ENGINEERING 131 
the last fifty years. It was the great pioneering labours of Sir Charles 
Parsons, however, which laid the main foundations for the turbine design 
of to-day. He saw the need for compounding his first turbine, of reaction 
type. This simple non-condensing turbine was naturally very un- 
economical, and as a result the condensing turbine was conceived, where- 
upon turbine steam consumptions and costs began to approximate to 
those of the best reciprocating engines. In the early stages of turbine 
development considerable difficulty arose from the fact of this prime 
mover being more suitable for large outputs, for which in those times 
there was no demand. Parsons next initiated the application of the 
turbine to ship propulsion, building the s.s. Turbinia, in which the pro- 
pellers were driven direct ; the result being that, while the turbine speed 
was too low, that of the propellers was too high to give the best results. 
In the meantime the experience gained on the Turbinia had resulted 
in the design and adoption of the geared turbine, which not only improved 
the position for the smaller sets on land, but also found the solution to 
the problem of marine propulsion—namely, a turbine running at a high 
speed and a propeller at a much lower one, thus producing a condition 
which gave maximum efficiency. 
Progress on the marine side has been so rapid that units capable of 
developing 50,000 shaft h.p. have been constructed. 
On land the progress has been no less rapid, and the application of the 
geared turbine has enabled continuous current dynamos to be built for 
capacities up to 3,000 kw. per machine. Further, the application of the 
geared turbine has been extended to operating various kinds of mills 
and to other fields where its greater economy of space and steam con- 
sumption give it advantages over the steam engine. 
Recent developments in turbine design have tended to endorse the 
principle laid down by Carnot, that the temperature of heat supply 
should be separated as widely as possible from that of heat rejection. 
Thus, total temperatures are creeping upwards. Among other means 
of improving the efficiency is that of feed heating by means of steam 
tapped off from the turbine between the expansions. 
There are many examples of large turbine plant approaching a thermal 
efficiency of 30 per cent. from fuel to electricity, and machines have been 
constructed giving, at the terminals, one kw.-hour for 10,000 B.Th.U., 
corresponding to a thermal efficiency of the turbine of more than 
34 per cent. Although there are turbines at present in commission 
developing 200,000 kw., these very large machines, I understand, show 
little, if any, improvement in efficiency over a machine having an output 
of, say, 40,000 to 50,000 kw. ; and it seems rather unlikely that the size 
of unit will tend to increase in the future. 
The development of the oil engine is another feature of cardinal im- 
portance in recent engineering history. It was only forty-one years ago 
that Dr. Rudolf Diesel obtained his famous patent which was destined to 
effect a revolution in the design of an oil engine. It was the intention of 
the inventor to burn coal direct in the working cylinder, but this was 
found to be impracticable, owing to the large quantities of unburnt 
residue. He thereupon turned to the possibilities of oil, and, after four 
