+--------------------+-----------+------------+----------+------------+ | | Stone. | Iron. | Bronze. | Lead. | | | _d._ | _d._ | _d._ | _d._ | +--------------------+-----------+------------+----------+------------+ | Price of 4” ball | 0.25 | 7.96 | 26.468 | 8.652 | | Price of powder | 5.12 | 14.07 | 15.44 | 20.496 | | Cost of one Round | 5.37 | 22.03 | 41.908 | 29.148 | | or in our money |4s. 5-3/4d.|18s. 4-1/4d.| 34s. 11d.|24s. 3-1/2d.| +--------------------+-----------+------------+----------+------------+ These figures do not profess to give the absolute price of one round, but they represent pretty accurately the relative cost of a round with the different projectiles. The pressures per square inch exerted upon the bore of a gun are directly proportional to the weight of the charges used, and these charges were directly proportional to the weights of the projectiles used. We have therefore the following comparative pressures:— TABLE XI _Numbers proportional to the pressures per square inch on the bore of a 4.25″ gun when fired with shot of different materials._ +--------+--------+--------+--------+ | Stone. | Iron. |Bronze. | Lead. | | 3.6 | 10 | 10.9 | 14.5 | +--------+--------+--------+--------+ Table X. shows that the cost per round with stone was much less than with metal shot, while Table XI. shows how great was the disparity between the pressures on the bore in the two cases, which, as the calibre (and therefore the absolute pressure) increased, became a serious matter. With the very small, early guns, the greater cost and heavier strain may not have been sensibly felt. The extra cost in their case was not very considerable, and the increased pressure may not have been even suspected until guns began to burst.[535] But that these disadvantages made themselves unmistakably felt when the guns grew larger is proved beyond a doubt by the fact that “great stone shot and great cannon were introduced together.”[536] Leaden bullets were retained for hand-guns, because it was comparatively easy to strengthen them, and the metal, although dearer per bullet than iron, was much easier to manipulate. Iron shot were doubtless used as a general rule for breaching purposes, for which stone shot were ill adapted, owing to their lightness and liability to break up. We even hear from time to time of the use of bronze and lead cannon balls. _Case._