NPS Images Before we explain the fuze cutter, you first have to understand how the fuze is constructed. The fuze is a metallic disc that has a circular chamber inside filled with a gunpowder mixture. The chamber leads to an opening on the bottom of the fuze, which, in turn, communicates with the hollow chamber in the middle of the projectile. (This chamber was filled with gunpowder.) The top of the fuze is marked with lines to represent one to five seconds, with each second sub-divided with markings for half-seconds and quarter-seconds (as shown in the second drawing). The fuze screws into the top of the projectile, as shown in the first drawing. Here’s where the fuze cutter comes in. Before loading the projectile into the cannon, one of the cannoneers used the fuze cutter to poke a hole in the top of fuze at the correct time marking. How did he know which time to choose? Each cannon had a “table of fire” that listed how long it took a projectile to travel a certain distance. The gunner (who was in charge of the gun crew) estimated the distance of the target, which determined which time marking to be “cut” on the fuze. For a mountain howitzer (one of the cannons commonly used by the troops at Fort Union), it would take a little over 3 seconds for an exploding shell to travel 850 yards (just about half a mile). So if the gunner called for “Shell, 850 yards,” the cannoneer “cut” the fuze at the 3.25 seconds mark. When the shell was loaded in the cannon and fired, the explosion in the cannon barrel reached the powder in the fuze through the hole at the 3.25 second mark. The powder inside the fuze would burn through the chamber for 3 ¼ seconds and then explode through the bottom of the fuze, igniting the main powder charge in the projectile. If all went right, the projectile would explode into pieces as it was reaching its target. |
Last updated: January 23, 2021