Copy letter from [John William Strutt] Lord Rayleigh, to Sir John Conroy 'Dear Sir J. Conroy, The referee upon your paper recommends that you should add a note referring to Tumblirz whose last paper was read to the Vienna Acad [Academy] published during course of last summer. It is reprinted in Wied. Ann. [Annalen der Physik] where a reference to former papers can be found. R. von Helmholtz's research is published separately by Leonhard Simion, Berlin. (signed) Rayleigh Sec. R.S. [Secretary, Royal Society]'. 19 December 1889