Referee's report by Hugh Longbourne Callendar, on a paper 'The optical properties of vitreous silica' by J W Gifford and William Ashwell Shenstone Sectional Committee: Physics and Chemistry Recommended for publication in Proceedings. The paper should be published in full, without modification and all the illustrations should be reproduced. The work appears to have been carefully performed and certainly forms an important addition to their knowledge of optical properties of substances, although nothing new in principle is involved. [Published in Proceedings of the Royal Society, 1904]. Endorsed on verso as received 4 February 1904. February 1904