First, the compound reaction turbine with which we have been dealing, representing over 90 per cent, of all marine turbines in use in the world, and about half the land turbines driving dynamos.
Second, the de Laval, which is only used for small powers.
Third, the "multiple impulse, compounded" or Curtis, which has been chiefly used on land, but which has been fitted in a few ships.
Lastly, a combination of the compound reaction type with one or more "multiple impulse or Curtis elements" at the high-pressure end to replace the reaction blading.
We may dismiss the other varieties as simply modifications of the original types without possessing any originality or scientific interest.
Now let me further explain the multiple impulse type, and commence by saying that it is the only substantial innovation in turbine practice since the compound reaction and the de Laval turbines came into use.
