_ROPE_—is always distinguished by its circumference: thus a two inch
rope means a rope of 2 inches in circumference.
_Rule for finding the Weight of Ropes._
Multiply the square of the circumference in inches, by the length in
fathoms, and divide the product by 480 for the weight in cwt. See also
_Drag Ropes_.
_SAND BAGS_—are made about 27 inches long, and 15 diameter; 250 of
these are required for each fathom of battery, or about 1680 for two
guns or mortars.—See _Tonnage_.
_SAP._—The sap generally commences about the second parallel, and
sometimes sooner; and if the fire of the besieged is much slackened,
may proceed both day and night. The sappers are usually divided into
brigades of 8, and subdivided into divisions of 4 each; being the
greatest number that can work at the sap at the same time. The leading
sapper excavates 18 inches deep, and as much wide; the second, third,
and fourth deepen the trench, each in succession 6 inches, and widen it
as much; so that the four make a trench of 3 feet wide and 3 feet deep;
after which the common workmen follow, and increase it in breadth and
depth equal to the other trenches. The sap may proceed at the rate of
80 fathoms in 24 hours. As this work is very hard, the half brigades
relieve each other every hour, and each sapper in his turn takes the
lead. The whole brigade is relieved at the end of 6 hours. It is always
customary in this dangerous work, to give the wages of those that are
killed to the survivors. Sappers are generally armed with a helmet and
breast plate. See _Trenches_, _Parallels_.
_SECANT._—See table at the end of the word _Gunnery_.
_SHELLS_—_For Mortars and Howitzers.—Their Dimensions, Weight, &c._
+-------+-------------+-------+---------+--------+--------------+-------+
|Nature.| Weight. | Diam- | Powder | Powder | Diameter of |Thick- |
| | | eter. |contained| for | Fuze Hole. |ness of|
| | | | in |Burning.+-------+------+ Metal.|
| | | | Shells. | |Outside|Inside| |
+-------+-------------+-------+---------+--------+-------+------+-------+
| |Ct.qr.lbs.oz.|Inches.| lbs. oz.|lbs. oz |Inches.|Inches|Inches.|
|13 Inch| 1 3 2 | 12¾ | 10 4 | 6 12 | 1.837 | 1.696| 2.05 |
|10 ” | 3 9 | 9¾ | 4 5 | 2 10 | 1.57 | 1.45 | 1.575 |
| 8 ” | 1 11½ | 7¾ | 2 12 | 1 14 | 1.219 | 1.127| 1.2 |
| 5½ ” | 15¼ | 5¼ | 1 | 12 | 0.894 | 0.826| 0.822 |
| 4⅖ ” | 8 | 4⅕ | 7 | 5 | 0.832 | 0.769| 0.653 |
+-------+-------------+-------+---------+--------+-------+------+-------+
| Hand | 3 11| 3.49 | | | | | |
| Gren. | 1 13| 2.77 | | 1½ | | | |
+-------+-------------+-------+---------+--------+-------+------+-------+
| _French Shells, in French Weights and Measures._ |
+-------+-------------+-------+---------+--------+-------+------+-------+
|Inches.| lbs. | | | |Lines |Lines | Lines.|
| | | | | | Po. | Po. | |
|12 Inch| 150 | 12 | 17 | 5 | 15 9 | 15 | 16 |
|10 ” | 100 | 10 | 10 | 3 | 15 9 | 15 | 16 |
| 8 ” | 43 | 8 | 4 1 | 1 | 12 | 11 | 10 |
| 6 ” | 23 | 6 | 2 8 | 12 | 11 | 10 6| 10 |
+-------+-------------+-------+---------+--------+-------+------+-------+
_Dimensions of Shells for Guns and Carronades made with an equal
Thickness of Metal._
+------------------------------------+------+------+------+------+------+
| Nature. |42 Pr.| 32 | 24 | 18 | 12 |
+------------------------------------+------+------+------+------+------+
| |Inches|Inches|Inches|Inches|Inches|
| Exterior| 6.684| 6.105| 5.547| 5.04 | 4.4 |
| Diameter of the shell Interior| 4.404| 4.005| 3.767| 3.4 | 2.8 |
+------------------------------------+------+------+------+------+------+
| Thickness of metal | 1.14 | 1.05 | 0.89 | 0.82 | 0.8 |
|Guns Exterior| 0.894| 0.894| 0.894| 0.832| 0.832|
| Diameter of fuze hole Interior| 0.826| 0.826| 0.826| 0.769| 0.769|
+------------------------------------+------+------+------+------+------+
| Powder for bursting oz. | 14 | 11 | 12 | 9 | 5½ |
+------------------------------------+------+------+------+------+------+
| Exterior| 6.64 | 6.05 | 5.48 | 4.935| 4.295|
| Diameter of shell Interior| 4.36 | 3.95 | 3.48 | 3.235| 2.695|
| +------+------+------+------+------+
|Carron- Thickness of metal | 1.14 | 1.05 | 1. | 0.85 | 0.8 |
| ades Shells Weight lbs. | | 22 | | 12 | |
| Contains powder oz. | | 12½ | | 9 | |
| Powder for bursting oz. | | 10 | | 7 | |
+------------------------------------+------+------+------+------+------+
_The following Shells may also be fired from Guns._
Hand Grenades from 6 Prs.
4⅖ Shells ” 12 Prs.
5½ Shells ” 24 Prs.
8 Inch ” 68 Pr. Carronades.
Shells may likewise be thrown from guns to short distances, in cases of
necessity, though the bore be not of a diameter sufficient to admit the
shell. For this purpose the gun may be elevated to any degree that will
retain the shell upon its muzzle, which may be assisted by a small line
going from the lugs of the shell round the neck of the gun. To produce
a greater effect, the space between the shell and the charge may be
filled with wads or other substance.