From the foregoing it will be seen that the structural features of all boilers are so arranged as to provide for the exposure of the largest possible area of water to a heated surface so that the greatest amount of heat from the fuel may be absorbed.
STEAM ENGINES
The first steam engine was an exceedingly simple affair. It had neither eccentric, cylinder, crank, nor valves, and it did not depend upon the pressure of the steam acting against a piston to drive it back and forth, because it had no piston.
It is one of the remarkable things in the history and development of mechanism, that in this day of perfected steam engines, the inventors of our time should go back and utilize the principles employed in the first recorded steam engine, namely, the turbine. Instead of pressure exerting a force against a piston, as in the reciprocating engine, the steam acted by impacting against a moving surface, and by obtaining more or less reaction from air-resistance against a freely discharging steam jet or jets.
The original engine, so far as we have any knowledge, had but one moving part, namely, a vertical tubular stem, to which was attached a cross or a horizontal tube.
The Original Engine.—Figure 8 is a side view of the original engine. The vertical stem A is pivoted to a frame B, and has a bore C which leads up to a cross tube D. The ends of the tube D are bent in opposite directions, as shown in the horizontal section, [Fig. 9].