Incomplete letter from J F W [John Frederick William] Herschel, to 'Dear Sir' [Edward Kater] The great respect that Herschel had for Kater's father [Henry Kater] would lead him to do as requested. He has heard Henry Kater speak of his escapements and rejoices that Edward has 'rescued it from oblivion'. He will forward it to the Royal Society's Secretary. The letter is cut and joined between the text and signature. [March 1840]