Referee's report by John Ambrose Fleming, on a paper 'Lines of induction in a magnetic field' by Henry Selby Hele-Shaw and Alfred Hay Sectional committee: Physics and Chemistry Recommended for publication in Philosophical Transactions, in full with no changes. The paper is exceedingly valuable and the author's findings a very important hydro-dynamical discovery. The discovery has been utilised in the paper for the pre-determination of magnetic fields in and around magnetic substances. If it proves too expensive to reproduce all the diagrams, the authors might be asked to select those they would desire to omit but they will be expensive to reproduce by photo-lithography. The majority of the illustrations are 'most beautiful and interesting confirmations of hydro-dynamical theory'. [Published in Philosophical Transactions A, 1900]. Endorsed on verso as received 29 June 1900. 28 June 1900