of the Long Inequality of Venus and the Earth; and some of his Optical researches were conducted jointly with Whewell.  Whewell took his degree in 1816, seven years before Airy, and his reputation, both for mathematical and all-round knowledge, was extremely and deservedly great, but he was always most generous in his recognition of Airy’s powers.  Thus in a letter of Mar. 16th, 1823 (Life of William Whewell by Mrs Stair Douglas), he says, “Airy is certainly a most extraordinary man, and deserves everything that can be said of him”; and again in the autumn of 1826 he writes to his aunt, “You mentioned a difficulty which had occurred to you in one of your late letters; how Airy should be made Professor while I was here, who, being your nephew, must of course, on that account, deserve it better than he could.  Now it is a thing which you will think odd, but it is nevertheless true, that Airy is a better mathematician than your nephew, and has moreover been much more employed of late in such studies....  Seriously speaking, Airy is by very much the best person they could have chosen for the situation, and few things have given me so much pleasure as his election.”  How much Whewell depended upon his 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: