The heat of shortening and the dynamic constants of muscle by A. V. Hill

Primary paper: doi.org/10.1098/rspb.1938.0050 . Author byline A. V. Hill; the author is Archibald Vivian Hill. Proceedings of the Royal Society B 126, 136–195 (1938). Author-paper scan: math.nyu.edu/~peskin/eb_lecture_notes/Hill_AV_1938.pdf . Part I, pp. 136–137: thermopile and optically amplified galvanometer recording; Part II: muscle heat, load and shortening; Part III, pp. 184–185: contractile and elastic components. The paper compares heat-measurement methods rather than treating a muscle as a passive spring.