Referee's report by George Francis Fitzgerald, on a paper 'Energy of rontgen & becquerel rays and the energy required to produce an ion in gases' by Professor Ernest Rutherford and R K McClung Sectional committee: Physics and chemistry Recommended for publication in Philosophical Transactions in full. It would be well to state the calories per second whenever this is meant. Similarly on page 19 the heading in the centre should be 'Total Power of the Rays' not 'Total Energy'. Consistent nomenclature should make this paper more intelligible to the reader. In a great many places 'power' might well be substituted for 'energy'. All the illustrations should be reproduced and it is a 'very important paper'. [Published in Philosophical Transactions A, 1901]. Endorsed on verso as received 12 July 1900. 11 July 1900