FOOTNOTES:
[1] In the siege of Strasburg, 1870, a bridge of beer casks was built across the ditch of Lunette No. 52, between nightfall and 10 P. M., September 21st. The ditch was about 66 feet wide and 9 to 10 feet deep. This bridge gave access to the lunette. It was subsequently sunk by the fire of the work and was replaced by a causeway.—Franco-German War, Official Account, Part 2, vol. 1., pp. 88, 89.
[2] One of a group of trees may frequently serve for this purpose.
[3] The charge for the 5" siege gun is 15 lbs. of powder; 200 rounds = 3,000 lbs.; 2 guns, 6,000 lbs.
[4] No special box has been adopted in our service. The English box is 1' 9" × 1' 5½" × 1' 5" outside, metal lined, and holds almost 100 lbs. of made-up cartridges.
[5] The crater radius of a mine with L. L. R. of 6' to 12' and a charge of 6,000 lbs. of powder would be about 44 feet ([Art. 7], Military Mining). The radius of the mound of earth thrown out would probably be three times this.
[6] Quoted from Mahan’s Siege Operations.
[7] A shell from a 9" .45 rifled mortar has in experimental firing produced in moderately hard ground a crater 8 feet deep and 19½ feet in diameter.
[8] From the unpublished records of three experimental mines fired at Willet’s Point in 1877-83 it would seem that the quantities given in this table are greater than those required if good American powder is used. These mines, in a soil of modified drift, used. These mines, in a soil of modified drift,
with a L. L. R. of 12 ft. required 1.02 lbs. per cu. yd. = 1 lb. ⅓ oz.; and
with a L. L. R. of 17 ft. required 1.15 lbs. per cu. yd. = 1 lb. 2½ oz.
[9] Six-lined craters (r = 3l) are generally considered as the practical limit of overcharged mines, although at Chatham mines have been fired giving r = (3¾)l. The published data concerning them indicate that they required charges larger than the formulas above given call for.