From Horace Darwin to G. H. Darwin 23 October 1875

Dear George

I have just found out what you want. In Cornish engines of good construction a little more 1/10 of the mechanical power of the coal is turned into useful work. In a horse 1/4. Bournes Steam Engine p 94. quoted from “Experiments & Observations on Mechanical power & Electromagnetism Steam and Horses” by W. Scoresby & J P Joule in supplemental no. of the Philosophical Magazine June 1845. I have just come across this by accident or would have sent it you before

Yours | H Darwin