On the Availability of Normal-Temperature Heat-Energy

Abstract

1. I WAS interested to see the letter of Prof. A. S. Herschel, in NATURE, vol. xviii. p. 39, referring to my papers on the subject of the derivation of work from normal-temperature heat (NATURE, vol. xvii. p. 31, and vol. xvii. p. 20). There is one qualification (not affecting the reasoning in my papers) I should like to make here, viz., the case there dealt with does not appear necessarily to be out of harmony with what is termed the “second law of thermodynamics”, though it may be questioned whether it quite harmonises with certain modes of stating the law. As the facts are of course the most important, it may perhaps be well just briefly to recapitulate here under what conditions normal-temperature heat can be converted into work, as affecting the problem dealt with.