friends at the Observatory may be gathered from a letter which he wrote to his sister on Dec. 21st, 1833. "We have lately been in alarm here on the subject of illness. Two very near friends of mine, Prof. and Mrs Airy, have had the scarlet fever at the same time; she more slightly, he very severely. They are now, I am thankful to say, doing well and recovering rapidly. You will recollect that I was staying with them at her father's in Derbyshire in the summer. They are, I think, two of the most admirable and delightful persons that the world contains." And again on Dec. 20th, 1835, he wrote to his sister Ann, "My friends--I may almost say my dearest friends --Professor Airy and his family have left Cambridge, he being appointed Astronomer Royal at Greenwich--to me an irreparable loss; but I shall probably go and see how they look in their new abode." Their close intercourse was naturally interrupted by Airy's removal to Greenwich, but their friendly feelings and mutual respect continued without material break till Whewell's death. There was frequent correspondence between them, especially on matters connected with the conduct and teaching of the University, in which they both took a keen interest, and a warm welcome at Trinity Lodge always awaited Mr and Mrs Airy when they visited Cambridge. In a letter written to Mrs Stair Douglas on Feb. 11th, 1882, enclosing some of Whewell's letters, there occurs the following passage: "After the decease of Mrs Whewell, Whewell wrote to my wife a mournful letter, telling her of his melancholy state, and asking her to visit him at the Lodge for a few days. And she did go, and did the honours of the house for several days. You will gather from this the relation in which the families stood." Whewell died on Mar. 6th, 1866, from the effects of a fall from his horse, and the following extract is from a letter written by Airy to Whewell's niece, Mrs Sumner Gibson, on hearing of the death of his old friend: "The Master was, I believe, my oldest surviving friend (beyond my own family), and, after an acquaintance of 46 years, I must have been one of his oldest friends. We have during that time been connected privately and officially: we travelled together and experimented together: and as opportunity served (but I need not say in very different degrees) we both laboured for our College and University. A terrible blank is left on my mind."