"I do not bind you to the size of the drum or wheels, only the room that the fly-wheel works in is but 7 feet wide.
"Query 1st.--The length of the piston, and the small variation that the beam will give it, is so trifling that it will not be felt.
"The cylinders that have been working on their sides for seven years past, are now working as well as any engine with upright cylinders, which is a proof that the little rubbing is of no consequence.
"Query 2nd.--The passage in the cock is equal to the passage we make in our large engines, which is only one-fortieth part of the piston; and as we shall work with high steam, we do not mind the pressing through the steam-passage; and as the steam will be very much expanded, it will not be felt in the passage to the condenser. I know where we have removed cylinders and put larger ones on the same nozzles and condensing work, and the engines did good duty.
"Query 3rd.--I find by experience that if you give double the quantity of injection to an engine one stroke, and none the other, that the quicksilver in the gauge will stand nearly the same; the cold sides of the condenser are sufficient to work an engine a great many strokes without any injection.
"Query 4th.--You may put a hanging to the air-pump bucket, and foot-valve; either that or a rising one will do very well, but I think the rising cover and wood face on the top, best.
"Query 5th.--The air-pump bucket is large enough. At Wheal Alfred they have a 64-inch cylinder; the air-pump is 20 inches, and the stroke is half that of the engine. They were afraid that it was too small; they then put another of 14 inches by the side of the first, the same stroke. The quicksilver tube stands as high with the one 20-inch bucket as with the two buckets; the engine works best with the one bucket. I have found by experience that size to be sufficient, and (especially in an engine that works quickly) make the cistern high enough to cover the condensing work well with water.
"Query 6th.--My reason for making the forcing pump with duck-valves is, because they do not bum like the others, and we find them seldom out of repair; but make it whichever way you think best, and work it in any way you like.