quitted selle Selle is the French for 'saddle'. Thus 'quitted selle and swum' means that he 'fell out of the saddle into the water (presumably when his horse refused to jump it), and swam for it.'
Alastair Wilson writes: He's swimming for it to reach the other bank (or if he's got any sense, the side on which his horse is) so that he can remount (if someone has caught his horse for him) to continue the chase, or to make his way to the nearest inn to get his clothes dried, and a large hot toddy inside him. There's a well-known cartoon of two fox-hunters leaping at full stretch over a brook - one says to the other "Who's that in the brook, there?" The other replies "That's the Parson". The first says "Oh, that's all right, leave him - we won't want him till next Sunday".
Few fox-hunting men would have used the word selle for a saddle. Kipling, with his encyclopaedic familiarity with English poetry, may well have remembered the expression from The Faerie Queen (II. viii. 31) of Edmund Spenser (1552-1599):
Yet was the force so furious and so fell,Surtees Robert Smith Surtees (1803-1864) was an English author much loved and quoted by Kipling, who wrote classic novels about hunting. In Stalky & Co. Stalky quotes extensively from Handley Cross, Mr Sponge's Sporting Tour, and Mr Romford's Hounds. (At that time Beetle was more keen on Browning, and Turkey on Ruskin).
Jorrocks is a grocer from London who lives for the chase. James Pigg is his huntsman, Artaxerxes one of his horses, and Binjimin his 'whipper-in', who controls the pack of hounds:
" Now, Binjimin," said Mr. Jorrocks, eyeing his whipper-in with one of his most scrutinising looks, "now, Binjimin," repeated he, with great dignity, "you are on the eve of a most mo-men-tous crisis!" [Handley Cross Chap 50, "Pomponius Ego", p.359]See The Surtees Society and the University of Glasgow Special Collections.
my run My chase after a fox.