battering piece" 6 inches longer than its 42-pounder
brother? John Mueller wondered about such inconsistencies and set out
to devise a new system of ordnance for England.

Like many men before him, Mueller sought to increase the caliber of
cannon without increasing weight. He managed it in two ways: he
modified exterior design to save on metal, and he lessened the powder
charge to permit shortening and lightening the gun. Mueller's guns had
no heavy reinforces; the metal was distributed along the bore in a
taper from powder chamber to muzzle swell. But realizing man's
reluctance to accept new things, he carefully specified the location
and size for each molding on his gun, protesting all the while the
futility of such ornaments. Not until the last half of the next
century were the experts well enough versed in metallurgy and interior
ballistics to slough off all the useless metal.

So, using powder charges about one-third the weight of the projectile,
Mueller designed 14-caliber light field pieces and 15-caliber ship
guns. His garrison and battering cannon, where weight was no great
disadvantage, were 18 calibers long. The figures in the table
following represent the principal dimensions for the four types of
cannon--all cast-iron except for the bronze siege guns. The first line
in the table shows the length of the cannon. To proportion the rest of
the piece, Mueller divided the shot diameter into 24 parts and used it
as a yardstick. The caliber of the gun, for instance, was 25 parts, or
25/24th of the shot diameter. The few other dimensions--thickness of
the breech, length of the gun before the barrel began its taper,
fortification at vent and chase--were expressed the same way.

-----------------------------------+-------+--------+-------+---------
| Field | Ship | Siege | Garrison
-----------------------------------+-------+--------+-------+---------
Length in calibers | 14 | 15 | 18 | 18
(Other proportions in 24ths of the shot diameter) |
Caliber | 25 | 25 | 25 | 25
Thickness of breech | 14 | 24 | 16 | 24
Length from breech to taper | 39 | 49 | 40 | 49
Thickness at vent | 16 | 25 | 18 | 25
Thickness at muzzle | 8 | 12-1/2 | 9 | 12-1/2
-----------------------------------+-------+--------+------