For rockets from ½ an ounce to one pound, the stick must be 60 diameters of the rocket in length: for rockets from one pound and upwards fifty or fifty two diameters. Their thickness at top about ½ a diameter, and their breadth very little more. Their square at bottom equal to ½ the thickness at top. +-------------+-------+------+------+-----+-------+-------+-------+ | Nature of | 6 Pr. | 4 Pr.| 2 Pr.|1 Pr.| ½ Pr. | ¼ Pr. | ⅛ Pr. | | Rockets. | | | | | | | | +-------------+-------+------+------+-----+-------+-------+-------+ | |Ft. In.| F. I.| F. I.|F. I.| F. I. | F. I. | F. I. | |Distance of | | | | | | | | | poise from | 4 1½ | 3 9 | 2 9 |2 1 | 1 10½ | 1 8 | 1 3 | | the point | | | | | | | | | of the cone | | | | | | | | +-------------+-------+------+------+-----+-------+-------+-------+ Rockets of between 3 and 4 inches diameter have been observed to ascend as high as 1000 or 1200 yards; but the height of common rockets is between 450 and 600 yards; and their flight usually short of 7 seconds. JONES, ROBINS, LAB. _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_.