Note 15 — Chapter III
Reading edition
Lord Rosse’s beautiful telescopes have been formed upon principles which appear to embrace the best possible conditions for obtaining a reflecting surface which should reflect the greatest quantity of light, and retain that property little diminished for a length of time. The alloy used for this purpose consists of tin and copper in atomic proportions, namely, one atom of tin to four atoms of copper, or by weight 58·9 to 126·4.—On the Construction of large Reflecting Telescopes: by Lord Rosse. Report of the Fourteenth Meeting of the British Association, 1844, p. 79.