Korva is a scroll of the internet’s best ideas.
Pay a third of the savings
Some mines already ran Newcomen engines, which were less efficient steam engines. Watt and Boulton went to those owners with an offer: the Watt engine would be supplied free, and the owner would pay a third of the money it saved on coal. It was hardware as a service, and years later Rolls-Royce charged airlines for jet engines in a similar way, by every hour the engine was in service.
The arrangement lined up the interests of seller and buyer. Coal was most expensive in Cornwall, where the tin mines sat a long way from any coalfield, so the first Watt engines were installed there. Those owners saved the most on coal, which meant Watt and Boulton made the most money.
A flat price of 100 guineas for an engine would have left them with none of that upside.
How did Watt's engine use less coal?
In a Newcomen engine, the cylinder was cooled with a spray of water on every stroke, and a great deal of fuel went into reheating it. Watt patented a separate condenser in 1769, which let the cylinder stay hot while the steam was condensed elsewhere. By commonly cited estimates, his engines used roughly a quarter of the coal.
Why was coal so costly in Cornwall?
Cornwall has no coalfield. Coal for its mines was shipped across the Bristol Channel from South Wales ports such as Swansea, and the freight added to every ton. The county's tin and copper mines were deep and wet, so their pumps burned a lot of it.
How do pay-by-the-hour engine deals work?
Under a power-by-the-hour contract, an airline pays a fixed fee for each hour an engine flies, and the fee covers maintenance and replacement parts. The manufacturer carries the cost of unplanned repairs, so its income depends on engines staying reliable. Rolls-Royce has offered contracts of this kind since the 1960s.
More from My First Million
