Copy letter, from Margaret Brodie Herschel to John Wrottesley , dated at Collingwood Copy of letter, copied by Isabella Herschel in 1875 as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Writing on John Frederick William Herschel's behalf, Margaret Herschel begs John Frederick William Herschel be excused from writing a memoir of C. F. Gauss, as John Frederick William Herschel is very ill. 25 March 1855