After the haymaking in the vale is finished, the itinerant families turn towards the lighter soils, where the corn crops are fast ripening, and soon leave the scene of their former labours fifty miles behind them. A few perhaps straggle back in time to assist in the latter part of the corn harvest on the heavy lands, if it has been delayed by the weather. The physicians say that change of air is essential to health: the migration of birds may not be without its effect upon their lives, quite apart from the search for food alone. The dry walls which sometimes enclose cornfields (built of flat stones) are favourite places with many birds. The yellowhammers often alight on them, so do the finches and larks; for the coarse mortar laid on the top decays and is overgrown with mosses, so that it loses the hard appearance of a wall. When the sparrow who has waited till you are close to him suddenly starts, his wings, beating the air, make a sound like the string of a bow pulled and released--to try it without an arrow. The dexterous way in which a bird helps itself to thistledown is interesting to watch. The thistle has no branch on which he can perch; he must take it on the wing. He flies straight to the head of the thistle, stoops as it were, seizes the down, and passes on with it in the bill to the nearest bough--much in the same way as some tribes of horsemen are related to pick up a lance from the ground whilst going at full speed. Many birds twirl their `r's;' others lisp, as the nightingale, and instead of `sweet' say `thweet, thweet' The finches call to each other, `Kywee, kywee--tweo--thweet,' which, whatever may be its true translation, has a peculiarly soothing effect on the ear. Swifts usually fly at a great height, and, being scattered in the atmosphere, do not appear numerous; but sometimes during a stiff gale they descend and concentrate over an open field, there wheeling round and to and fro only just above the grass. Then the ground looks quite black with them as they dart over it: they exhibit no fear, but if you stand in the midst come all round you so close that they might be knocked down with a walking-stick if used quick enough. In the air they do not look large, but when so near as this they are seen to be of considerable size. The appearance of hundreds of these jet black, long-winged birds, flying with marvellous rapidity and threading an inextricable maze almost, as it were, under foot is very striking.