Referee's report by George Gabriel Stokes, on a paper 'On the geometrical representation of the expansive action of heat, and the theory of thermo-dynamic engines' by William John Macquorn Rankine Recommended for publication in the 'Philosophical Transactions of the Royal Society'. Considers paper to be covering and summarising an area of research which is relatively new, even if the principles contained within are not original. Author forgets to define certain terms with which me is familiar, but the reader may not be. Subject: Physics, Mathematics [Published in the Philosophical Transactions of the Royal Society] 29 April 1854