Copy of draft letter, from Sir John Herschel to Giovanni Antonio Plana Copy of draft letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Apologizes for delay in writing. Describes John Frederick William Herschel's travels across Europe back to England. Is sending Giovanni Antonio Plana copies of John Frederick William Herschel's papers in physics, mathematics, and astronomy, especially double stars. Describes a new instrument, a floating collimator, described by Henry Kater at the Royal Society [of London] [Rough notes for a later letter on the back of part of this one.] 14 January 1825