One plan I tried depended for its action on the difference of weight between a sparrow and a tit. It was the opposite of the arrangement by which sparrows are prevented from appropriating the food put out for pheasants, where the pheasant opens the corn-box by his weight on the perch outside. I tried so to arrange the balance that the heavier sparrow was cut off from the hole which contained the food, whilst for the tit it remained open. The practical drawback to this plan was the nicety of adjustment required, for though a sparrow is more than twice the weight of a tom-tit, the difference between the two weights is little more than a quarter of an ounce. One of the most successful contrivances, after all, is one of the simplest. Take a tin canister (one that I used was three inches long by 2-1/2 in diameter), hang it open end downwards by a string brought through a hole in the other end, to this string fasten inside the tin a bit of wood about the thickness of a large pencil, and let it hang like the clapper in a bell, projecting a quarter of an inch below the bottom rim of the tin. Plaster all round the inside of the tin with fat, leaving the wooden tongue in the middle free for the birds to cling to. In this way both great-tits and tom-tits can feed themselves without difficulty, but only one sparrow in twenty can manage with much ado to hold on and to eat at the same time. (To see a sparrow with his less-practised feet clinging to the edge of the tin, back downwards, just like a tit and helping himself to its contents is a good example of the energetic enterprise and the adaptability of his nature.) Robins do sometimes hold on to the tin in the same way, but generally they get quite as much as they want by flying up and pecking at the fat. They seem able to aim very accurately, and when the tin is nearly empty can make sure of the smallest fragments. Sparrows also attack the food in the same way by flying up at it, but they seem to find it more awkward, owing, perhaps, to the small space between the sides of the tin and the wood in the middle, which barely gives room for their larger heads and clumsier beaks.