Letter, from William Edward Parry to Sir John Herschel, dated at Admiralty Autograph letter signed by sender. Regrets delay in answering John Frederick William Herschel's communication, but was away from Bath when the letter arrived. Interested in the extraordinary local attraction observed by Mr. Duncan in 1791. Gives locations of three such situations in his recent voyage. Comments on the use of Peter Barlow's plate. Will write to Barlow before his next voyage. 4 January 1824