[Illustration:  MOUNTING A GUN.]

Cannon are cast in a solid mass of metal, either of iron or brass; they are then bored by being placed upon a machine which causes the whole mass to turn round very rapidly.  The boring tool being pressed against the cannon thus revolving, a deep hole is made in it, called the bore.

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THE TREE KANGAROO AND BLACK LEOPARD.

The ordinary mode in which the Kangaroos make their way on the ground, as well as by flight from enemies, is by a series of bounds, often of prodigious extent.  They spring from their hind limbs alone, using neither the tail nor the fore limbs.  In feeding, they assume a crouching, hare-like position, resting on the fore paws as well as on the hinder extremities, while they browse on the herbage.  In this attitude they hop gently along, the tail being pressed to the ground.  On the least alarm they rise on the hind limbs, and bound to a distance with great rapidity.  Sometimes, when excited, the old male of the great kangaroo stands on tiptoe and on his tail, and is then of prodigious height.  It readily takes to the water, and swims well, often resorting to this mode of escape from its enemies, among which is the dingo, or wild dog of Australia.

[Illustration:  TREE KANGAROO, AND BLACK LEOPARD.]

Man is, however, the most unrelenting foe of this inoffensive animal.  It is a native of New Holland and Van Diemen’s Land, and was first discovered by the celebrated navigator Captain Cook, in 1770, while stationed on the coast of New South Wales.  In Van Diemen’s Land the great kangaroo is regularly hunted with fox-hounds, as the deer or fox in England.

The Tree Kangaroo, in general appearance, much resembles the common kangaroo, having many of that animal’s peculiarities.  It seems to have the power of moving very quickly on a tree; sometimes holding tight with its fore feet, and bringing its hind feet up together with a jump; at other times climbing ordinarily.

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In the island of Java a black variety of the Leopard is not uncommon, and such are occasionally seen in our menageries; they are deeper than the general tint, and the spots show in certain lights only.  Nothing can exceed the grace and agility of the leopards; they bound with astonishing ease, climb trees, and swim, and the flexibility of the body enables them to creep along the ground with the cautious silence of a snake on their unsuspecting prey.

In India the leopard is called by the natives the “tree-tiger,” from its generally taking refuge in a tree when pursued, and also from being often seen among the branches:  so quick and active is the animal in this situation, that it is not easy to take a fair aim at him.  Antelopes, deer, small quadrupeds, and monkeys are its prey.  It seldom attacks a man voluntarily, but, if provoked, becomes a formidable assailant.  It is sometimes taken in pitfalls and traps.  In some old writers there are accounts of the leopard being taken in trap, by means of a mirror, which, when the animal jump against it, brings a door down upon him.