Not far from the picturesque house built by Decimus Burton, in one of the cages fronting the office of the superintendent of the gardens, is to be seen a beaver. The wonderful instinct of this little animal is certainly not inferior to that of the huge elephant. As yet he has not been placed in circumstances to enable the public to witness his building capacities; but it is the intention, we understand, of the Council to give him a stream of running water and the requisite materials to construct one of those extraordinary dams for which this animal is so famous. In Canada, where he used to flourish, the backwoodsmen often came upon hill-sides completely cleared of good-sized trees by colonies of these little creatures, who employed the felled timber to construct their dams--dams, not of a few feet in length, but sometimes of a hundred and fifty feet, built according to the best engineering formula for resisting the pressure of water, namely, in an angle with its apex pointed up the stream, and gradually narrowing from base to summit. In short, Mr. Brunel himself could not outdo your beaver in his engineering operations. Even in confinement this sagacious Rodent loves to display his skill, as we may learn from Mr. Broderip's account of his pet Binney:-- "Its building instinct," says that accomplished naturalist, "showed itself immediately it was let out of its cage, and materials were placed in its way, and this before it had been a week in its new quarters. Its strength, even before it was half-grown, was great, it would drag along a large sweeping-brush, or a warming-pan, grasping the handle with its teeth, so that the load came over its shoulder, and advancing in an oblique direction till it arrived at the part where it wished to place it. The long and large materials were always taken first; and two of the longest were generally laid crosswise, with one of the ends of each touching the wall, and their other ends projecting out into the room. The area caused by the cross-brushes and the wall he would fill up with hand-brushes, rush baskets, books, boots, sticks, cloths, dried turf, or anything portable. As the work grew high, he supported himself on his tail, which propped him up admirably; and he would often, after laying on one of his building materials, sit up over against it, appearing to consider his work, or, as the country people say, 'judge it.' This pause was sometimes followed by changing the position of the materials, and sometimes they were left in their place. After he had piled up his materials in one part of the room (for he generally chose the same place), he proceeded to wall up the space between the feet of a chest of drawers which stood at a little distance from it, high enough on its legs to make the bottom a roof for him, using for this purpose dried turf and