Incomplete copy letter, from Sir John Herschel to H. Turberville, dated at Collingwood Copy of letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Explains HT's problem with the defective telescope glass. Advises caution about entering optical glass manufacturing. Urges HT to take back his will from John Frederick William Herschel's possession and entrust it to the care of a legal advisor. 17 March 1868