Letter, from William Radcliffe Birt to Sir John Herschel, dated at Bethnal Green Autograph letter signed by sender. Wishes to embody in his reports on atmospheric waves details of John Frederick William Herschel's work in this field. Would like his comments on his suggested wording. Can E. W. Brayley borrow Karl Kreil's book? Nothing from Madras yet. 13 February 1849