Propulsive Power.--The Pea-shooter and its Powers.--An Attack repulsed.--Clay Bullets.--Puff and Dart.--The Sumpitan of Borneo, and its Arrows.--The Zarabatana or Pucunha of South America, and its Arrows.--The Air-gun.--Modern Firearms.--The Chœtodon, or Archer-fish.--The Pneumatic Railway.--The Throwing-stick and its Powers.--Australians, Esquimaux, and New Caledonians.--Principle of the Sheath.--Waganda Spears.--Sheathed Piercing Apparatus of the Gnat, Flea, and Bombylius.--Indian Tulwar and Cat’s Claw.--The Surgeon’s Lancet, and Piercing Apparatus of the Gad-fly and Mosquito. We will now take some of the analogies between Projectile Weapons of Art and Nature, selecting those in which the propulsive power is air or gases within a tube. Whether the weapon be a blow-gun, an air-gun, or a firearm of any description, the principle is the same. We will take them in succession, choosing first those of the simplest and most primitive character. Taking ourselves as examples, and looking upon the toys of children as precursors of more important inventions, we find that the simplest and most primitive of projectiles is the Pea-shooter, so familiar to all boys. Insignificant as is the little tin tube, and small as are the missiles which are propelled through it, the blow which can be struck by a pea properly shot is no trifle. At college I have seen a night attack upon an undergraduate’s rooms successfully repelled by a pea-shooter made for the nonce of a glass tube, the owner of the rooms having a taste for chemicals, and possessing a fair stock of the usual apparatus. Though the assaulted rooms were on the top set, and the assailants began their storming approaches below, the peas were too much for the stones, taking stinging effect on the hands and faces, and preventing any good aim being taken at the windows. Only two panes of glass were broken through a siege that lasted for several hours. There is another toy which is a development of the pea-shooter, and carries a small clay bullet instead of a pea. When the tube is quite straight and the balls fit well, the force of this missile is very great, as it can be used for killing small birds. Indeed, such an instrument is largely employed by the native hunters in procuring humming-birds for the European market. These weapons are generally lined with metal in this country, but a simple bamboo tube is sufficient for the native hunters. A still further improvement occurs where the place of the bullet is taken by a small dart or arrow, which is usually made to fit the bore by having a tuft of wool, or some similar substance, at the butt. The arrow is aimed at a target, and the toy is popularly known as “Puff and Dart.”