A 4.7-inch field gun fires projectiles weighing 60 pounds, with the same velocity.
A 6-inch howitzer fires projectiles weighing 120 pounds, with a muzzle velocity of 900 feet per second.
The principal difference between the field gun and the howitzer is that the latter can be pointed at a high angle, to assail infantry protected by intrenchments, or for other purposes.
While reference has been made to siege guns, which were used by the Germans in their attacks on the Belgian and French forts, the fact is that the large caliber mortars and howitzers are what wrought the havoc.
The large caliber howitzers and mortars throw shells containing huge charges of explosives, and are more adaptable in their application than the ordinary siege guns or cannons.
One novelty which had not been used up to the entrance of the United States into the war is a device invented by a Los Angeles man, which makes a "periscope gun" of any ordinary service piece.
In trench warfare, as developed abroad, the periscope has been used by the men in the trenches to observe the movements of the opposing forces and watch for scouts without exposing themselves to the fire of "snipers" or sharpshooters, who are always looking for a head or mark to aim at.
The new device comprises two mirrors attached to the gun by a metal frame in such manner that one mirror is above the range of vision and reflects the image to be fired at upon the other mirror below the stock or butt of the gun. The attachment enables the soldier sitting in a trench or shelter to accurately aim his gun and conveniently shoot while his head is kept below the safety line, or top of the parapet, or properly built trench.
THE TRENCH PERISCOPE.
With this attachment, approved by the United States Ordnance Department, a rifleman, from his concealed point of vantage, can survey a 30-foot field at 200 yards. The attachment can be removed at will and the metal bars and parts can be easily carried. The device adds about one and one-half pounds to the weight of the gun.