Note 144 — Chapter XII · Boulton and Watt begin the Manufacture of Steam-engines.

Watt was himself occupied, during his temporary residence at Broseley, in devising improvements in the details of his engine. Boulton says—“I observe you are thinking of making an inverted cylinder. Pray how are you to counterbalance the descent of the piston and pump rods, which will be a vast weight? If by a counterweight you gain nothing. But if you can employ the power that arises from the descent of that vast weight to strain a spring that will repay its debts—if by it you can compress air in an iron cylinder which in its return will contribute to overcome the vis inertiæ of the column of water to be raised, you will thereby get rid of that unmechanical tax, and very much improve the reciprocating engine.”—Boulton to Watt, 24th February, 1776. Boulton MSS.