I am not quite satisfied with this title, but it is the best that I can find. By it I mean that mode of mechanism which, by means of an array of sharp spikes, permits an animal to enter a passage easily, and yet prevents it from emerging. [Illustration: COCOON OF EMPEROR-MOTH. CRAB-POT. EEL-POT. MOUSE-TRAP.] Whether or not this principle be now employed in warfare I cannot say, but it is at all events used extensively in a small way of hunting, the best known of which is the wire Mouse-trap, one of which is shown at Fig. C on the illustration. A glance at the figure will explain the trap, even to those who have never seen it. It is composed entirely of wire, and has several round holes just above its lower edge. Each of these holes is the entrance to a conical tunnel made of wires with sharpened ends. The mouse, being attracted by a bait placed within the trap, tries to get at it. The doomed animal soon finds its way to one of the entrances, and with little difficulty pushes itself through the tunnel. Entering, however, is one thing, and returning is another. The wire yielded easily enough in one direction, but for the mouse to force itself against the converging points is an impossible task. Readers of the last century literature may perhaps remember, in the pages of “Peter Pindar,” a very clever and sarcastic account of the astonishment created in the mind of George III. by a mouse-trap seen accidentally in the house of a widow living at Salt Hill. “Eager did Solomon, so curious, clap His rare round optics on the widow’s trap, That did the duty of a cat. And, always fond of useful information, Thus wisely spoke he with vociferation,-- ‘What’s that? what? what? Hæ, hæ? what’s that?’ To whom replied the mistress of the house, ‘A trap, an’t please you, sir, to catch a mouse.’ ‘Mouse--catch a mouse!’ said Solomon with glee; ‘Let’s see, let’s see--’tis comical--let’s see-- Mouse! mouse!’--then pleased his eyes began to roll-- ‘Where, where doth he go in?’ he marvelling cried. ‘There,’ pointing to the hole, the dame replied. ‘What! here?’ cried Solomon, ‘this hole? this hole?’ Then in he pushed his finger ’midst the wire, That with such pains that finger did inspire, He wished it out again with all his soul.” For my part I think that the King was quite right. If he did not know the philosophy of a mouse-trap he ought to have asked, and to have been rewarded, as in that case, by catching with a trap of his own baiting, six mice on six successive days. At Fig. B on the same illustration is shown the simple apparatus by which crabs and lobsters are caught. The reader will see that the principle is exactly the same in both cases, the only difference being in material, the mouse-trap being made of wire, and the crab-pot of wicker.