Copy of letter, from Sir John Herschel to Henry Kater, dated at [Slough] Copy of letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Misplaced papers are now found. Henry Kater must be 'first authority' on scale constructed for Wilhelm Struve. John Frederick William Herschel improved telescope by separating eyepiece lenses. John Frederick William Herschel's new baby girl. 3 April 1830