New and Correct Globes
The Solar System, or the orbits of the planets
The Sun is placed in the midst of an immense space, wherein six opaque spherical bodies revolve about him as their center. These wandering globes are called the Planets, who, at different distances, and in different periods, perform their revolutions from West to East, in the following order: 1. ☿ Mercury is nearest to the Sun of all the planets, and performs its course in about three months. 2. ♀ Venus in about seven months and a half. 3. ♁ The Earth in a year. 4. ♂ Mars in about two years. 5. ♃ Jupiter in twelve. And lastly, ♄ Saturn, whose Orbit includes all the rest, spends almost 30 years in one revolution round the Sun. The distances of the Planets from the Sun are nearly in the same proportion as they are represented in figure. Supposing the distance of the Earth from the Sun to be divided into 10 equal parts; that of Mercury will be about 4 of these parts; of Venus 7; of Mars 15; of Jupiter 52; and that of Saturn 95.
The Great Orrery
The 1.65-Inch Hotchkiss Mountain-Gun Carriage
The carriage-body consists of two steel brackets forming cheeks and trail. They are reinforced by angle-steel and connected by transoms. The axle is secured in beds riveted to the brackets, and is arranged to be readily dismounted when required. The elevating-gear consists of a simple screw working in a stout steel transom, and supports the breech of the gun; the preponderance is sufficient to insure stability. The sponge and rod are secured to the right side of the trail by suitable attachments. A pole is provided for draught when easy country is encountered, and provision is made for attaching it to the lunette.
The 1.65-Inch Hotchkiss Mountain-Gun Mechanism
The Mechanism.—(b) breech-block; loading-hole; (s) stop-bolt; spring washer; (r) stop-bolt guide; (e) extractor; (h) extractor-hook; (a k) extractor-guide; (c) locking-screw; locking-screw shaft; locking-screw pin; (l) handle; stop; stop keep-screw. Action of the mechanism The gun having been fired, the handle is turned to the rear, unlocking the block and starting it in the mortise. Drawing the handle smartly to the right, the breech is opened, the extractor, actuated by the movement of the block, commences to move very slowly back with a powerful leverage, starting the cartridge-case from its seat. When the breech-block has moved sufficiently to unmask the bore, the change of direction in the extractor-guide causes the extractor to make a quick movement to the rear, throwing the cartridge clear of the gun. A new charge being inserted, it is pushed home until the head of the cartridge brings up against the extractor. The breech is now closed by pushing it smartly to the left, and is locked by turning the handle to the front. A primer may now be inserted in the vent, and the gun is ready for firing.
The 1.65-Inch Hotchkiss Mountain-Gun
Material steel Total length 3.83 feet Length of bore 3.43 feet Travel of projectile 3.10 feet Calibre 1.65 inches Weight 121 pounds Grooves 10 Twist of rifling, uniform 1 in 29.83 cals. Muzzle-velocity 1298 ft.-sec. Maximum range 3500 yards