Copy letter, from Sir John Herschel to Macedonio Melloni Copy of letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Will do all in his power to ensure that Macedonio Melloni receives copies of the publications relating to the Fixed Observatories. Does not think Macedonio Melloni could have seen a copy of John Frederick William Herschel's paper on photographic action when he wrote the notice in Annales de chimie. Comments on this paper and more recent experiments in this field. 23 February 1841