Part 9 (1/2)
[Ill.u.s.tration: Figure 44--EIGHTEENTH CENTURY GUNNER'S EQUIPMENT. (Not to scale.)]
The ladle full of powder was pushed home in the bore. Turning the handle dumped the charge, which then had to be packed with the rammer.
As powder charges were lessened in later years, the ladle was shortened; by 1750, it was only three shot diameters long. With cartridges, the ladle was no longer needed for loading the gun, but it was still handy for withdrawing the round.
_The rammer_ was a wooden cylinder about the same diameter and length as the shot. It pushed home the powder charge, the wad, and the shot.
As a precaution against faulty or double loading, marks on the rammer handle showed the loaders when the different parts of the charge were properly seated.
_The gunner's pick or priming wire_ was a sharp pointed tool resembling a common ice pick blade. It was used to clear the vent of the gun and to pierce the powder bag so that flame from the primer could ignite the charge.
[Ill.u.s.tration: Figure 45--SIXTEENTH CENTURY PATTERN FOR GUNNER'S LADLE.]
_Handspikes_ were big pinch bars to manhandle cannon. They were used to move the carriage and to lift the breech of the gun so that the elevating quoin or screw might be adjusted. They were of different types (figs. 33a, 44), but were essentially 6-foot-long wooden poles, shod with iron. Some of them, like the Marsilly handspike (fig. 11), had rollers at the toe so that the wheelless rear of the carriage could be lifted with the handspike and rolled with comparative ease.
_The gunner's quadrant_ (fig. 46), invented by Tartaglia about 1545, was an aiming device so basic that its principle is still in use today. The instrument looked like a carpenter's square, with a quarter-circle connecting the two arms. From the angle of the square dangled a plumb bob. The gunner laid the long arm of the quadrant in the bore of the gun, and the line of the bob against the graduated quarter-circle showed the gun's angle of elevation.
The addition of the quadrant to the art of artillery opened a whole new field for the mathematicians, who set about compiling long, complicated, and jealously guarded tables for the gunner's guidance.
But the theory was simple: since a cannon at 45 elevation would fire _ten_ times farther than it would when the barrel was level (at zero elevation), the quadrant should be marked into _ten_ equal parts; the range of the gun would therefore increase by _one-tenth_ each time the gun was elevated to the next mark on the quadrant. In other words, the gunner could get the range he wanted simply by raising his piece to the proper mark on the instrument.
[Ill.u.s.tration: Figure 46--SEVENTEENTH CENTURY GUNNER'S QUADRANT. The long end of the quadrant was laid in the bore of the cannon. The plumb bob indicated the degree of elevation on the scale.]
Collado explained how it worked in the 1590's. ”We experimented with a culverin that fired a 20-pound iron ball. At point-blank the first shot ranged 200 paces. At 45-degree elevation it shot ten times farther, or 2,000 paces.... If the point-blank range is 200 paces, then elevating to the _first_ position, or a tenth part of the quadrant, will gain 180 paces more, and advancing another point will gain so much again. It is the same with the other points up to the elevation of 45 degrees; each one gains the same 180 paces.” Collado admitted that results were not always consistent with theory, but it was many years before the physicists understood the effect of air resistance on the trajectory of the projectile.
_Sights_ on cannon were usually conspicuous by their absence in the early days. A dispart sight (an instrument similar to the modern infantry rifle sight), which compensated for the difference in diameter between the breech and the muzzle, was used in 1610, but the average artilleryman still aimed by sighting over the barrel. The Spanish gunner, however, performed an operation that put the bore parallel to the gunner's line of sight, and called it ”killing the _vivo_” (_matar el vivo_). How _vivo_ affected aiming is easily seen: with its bore level, a 4-pounder falconet ranged 250 paces. But when the _top of the gun_ was level, the bore was slightly elevated and the range almost doubled to 440 paces.
To ”kill the _vivo_,” you first had to find it. The gunner stuck his pick into the vent down to the bottom of the bore and marked the pick to show the depth. Next he took the pick to the muzzle, stood it up in the bore, and marked the height of the muzzle. The difference between the two marks, with an adjustment for the base ring (which was higher than the vent), was the _vivo_. A little wedge of the proper size, placed under the breech, would then eliminate the troublesome _vivo_.
During the first half of the 1700's Spanish cannon of the ”new invention” were made with a notch at the top of the base ring and a sighting b.u.t.ton on the muzzle, and these features were also adopted by the French. But they soon went out of use. There was some argument, as late as the 1750's, about the desirability of casting the muzzle the same size as the base ring, so that the sighting line over the gun would always be parallel to the bore; but, since the gun usually had to be aimed higher than the objective, gunners claimed that a fat muzzle hid their target!
[Ill.u.s.tration: Figure 47--SEVENTEENTH CENTURY GUNNER'S LEVEL. This tool was useful in many ways, but princ.i.p.ally for finding the line of sight on the barrel of the gun.]
Common practice for sighting, as late as the 1850's, was to find the center line at the top of the piece, mark it with chalk or filed notches, and use it as a sighting line. To find this center line, the gunner laid his level (fig. 47) first on the base ring, then on the muzzle. When the instrument was level atop these rings, the plumb bob was theoretically over the center line of the cannon. But guns were crudely made, and such a line on the outside of the piece was not likely to coincide exactly with the center line of the bore, so there was still ample opportunity for the gunner to exercise his ”art.”
Nonetheless the marked lines did help, for the gunner learned by experiment how to compensate for errors.
Fixed rear sights came into use early in the 1800's, and tangent sights (graduated rear sights) were in use during the War Between the States. The trunnion sight, a graduated sight attached to the trunnion, could be used when the muzzle had to be elevated so high that it blocked the gunner's view of the target.
Naval gunnery officers would occasionally order all their guns trained at the same angle and elevated to the same degree. The gunner might not even see his target. While with the crude traversing mechanism of the early 1800's the gunners may not have laid their pieces too accurately, at least it was a step toward the indirect firing technique of later years which was to take full advantage of the longer ranges possible with modern cannon. Use of tangent and trunnion sights brought gunnery further into the realm of mathematical science; the telescopic sight came about the middle of the nineteenth century; gunners were developing into technicians whose job was merely to load the piece and set the instruments as instructed by officers in fire control posts some distance away from the gun.
THE PRACTICE OF GUNNERY
The old-time gunner was not only an artist, vastly superior to the average soldier, but, when circ.u.mstances permitted, he performed his wizardry with all due ceremony. Diego Ufano, Governor of Antwerp, watched a gun crew at work about 1500:
”The piece having arrived at the battery and being provided with all needful materials, the gunner and his a.s.sistants take their places, and the drummer is to beat a roll. The gunner cleans the piece carefully with a dry rammer, and in pulling out the said rammer gives a dab or two to the mouth of the piece to remove any dirt adhering.”
(At this point it was customary to make the sign of the cross and invoke the intercession of St. Barbara.)
”Then he has his a.s.sistant hold the sack, valise, or box of powder, and filling the charger level full, gives a slight movement with the other hand to remove any surplus, and then puts it into the gun as far as it will go. Which being done, he turns the charger so that the powder fills the breech and does not trail out on the ground, for when it takes fire there it is very annoying to the gunner.” (And probably to the gentleman holding the sack.)
”After this he will take the rammer, and, putting it into the gun, gives two or three good punches to ram the powder well in to the chamber, while his a.s.sistant holds a finger in the vent so that the powder does not leap forth. This done, he takes a second charge of powder and deposits it like the first; then puts in a wad of straw or rags which will be well packed to gather up all the loose powder. This having been well seated with strong blows of the rammer, he sponges out the piece.
”Then the ball, well cleaned by his a.s.sistant, since there is danger to the gunner in b.a.l.l.s to which sand or dirt adhere, is placed in the piece without forcing it till it touches gently on the wad, the gunner being careful not to hold himself in front of the gun, for it is silly to run danger without reason. Finally he will put in one more wad, and at another roll of drums the piece is ready to fire.”
Maximum firing rate for field pieces in the early days was eight rounds an hour. It increased later to 100 rounds a day for light guns and 30 for heavy pieces. (Modern non-automatic guns can fire 15 rounds per minute.) After about 40 rounds the gun became so hot it was unsafe to load, whereupon it was ”refreshed” with an hour's rest.
[Ill.u.s.tration: Figure 48--LOADING A CANNON. Muzzle-loading smoothbore cannon were used for almost 700 years.]