EXPLANATION OF THE PLATES. 
351 
There will, I think, be some advantage in making the pistons act together, 
because the effect will be as great as by dividing it, supposing both methods to be 
perfect; and in acting together, there would be less interference of the motion of 
the one with that of the other. The slide would be best moved from curved teeth 
on the beams. See art. 481. 
For the proportions and construction of the boiler, see art. 244, 227, 278, and 
522—526; for the engines, see art. 271—380; and for the power required, see 
art. 590.