Copy of draft letter, from Sir John Herschel to George Biddell Airy, dated at Slough Copy of draft letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Comments on George Biddell Airy's and Edward Sabine's work on the figure of the earth; describes some results John Frederick William Herschel obtained from using quartz for polarizing light, and is unhappy with the proposed recipient of the R.A.S. medal, M. C. T. Damoiseau, whose lunar theory John Frederick William Herschel cannot understand. 29 December 1830