made in peaceful pursuits, and to illustrate this I will take the case of the Internal Combustion Engine.
This is an application of our old friend "explosive combustion" to a very homely and peaceable purpose. The intimate mixture of combustible and oxygen is obtained by rapidly drawing into the cylinder a charge of petroleum vapour and the air requisite for its combustion with a rapidity that ensures their being churned up together and intimately mixed. The mixture is then lighted and the explosion that ensues drives the piston forward and makes the stroke. Such an engine therefore needs no supply from outside except the petrol that it burns. Boilers with their fires and their water supply (or its equivalent—their condenser system) disappear and this change is accompanied by a gain and not a loss of efficiency. This type of motor was in far too undeveloped a state to figure in the War of 1870 but it has been made the subject of years of highly scientific work in the hands of Sir Dugald Clerk and others until it has
