NOTE Numbers 9.
PREPARATION OR MANUFACTURE OF SIEGE MATERIAL.
I. Wooden gabions, fascines, sap fagots, and sap-rollers.
From August 11 to September 9, a detail of 25 engineers and 75 infantry made, on Folly Island, 1,429 gabions, 3 feet long and 2 feet in diameter; 11 sap-roller gabions, 4 feet in diameter and from 7 to 9 feet long; 162 fascines, 9 inches in diameter and 3 feet long. Not more than two-thirds of the gabions were expended in the siege.
The detachment above mentioned was subdivided as follows:
A gabion party consisted of 2 engineers and 4 infantry, who made, as a stint, 7 gabions per day.
A fascine party consisted of 3 engineers and 9 infantry, who made 12 fascines 18 feet long, or 16 of the shorter lengths, or 24 sap fagots, per day.
A sap-roller party consisted of 2 engineers and 8 infantry, who made 2 sap-roller gabions, 4 feet in diameter and 7 or 9 feet long, in three days.
Each squad got out its own material, which was tolerably convenient.
The engineers only were instructed in the duty.
Twenty-eight gabions, or from 8 to 12 fascines, made a load for a four-horse team.
II. Iron gabions and sap-rollers.
For each iron gabion there are required 44 pounds of hoop iron, .058 inch thick, and Numbers 17 wire gauge; thirty iron rivets, flat headed, 18 inches in diameter, and Numbers 7 wire guage; 8.5 square feet of pine boards; five hours' labor of 1 skilled man.
this estimate of the amount of labor required presupposes its application in the most advantageous manner, which was found to be as follows, the working party consisting of 10 men:
Four carpenters to prepare the stakes.
Two smiths to make the hoops.
Four artificers to assemble the gabion.
The dimensions of the web are 6.84 feet long by 3 feet wide. The stakes project from the gabion 3 inches, making its total height 3.25 feet, its diameter being 2 feet. The average weight of iron gabions is 60 pounds. If the hoops iron be of uniform thickness, its width will not affect the quantity required. That used in the siege was from 1 to 1.5 inches wide.
The approximate cost of the material for an iron gabion, at present prices (iron 7 cents per pound and boards 7 cents per foot) is $4.
Material required for a sap-roller 9 feet long and 4 feet in diameter, made with an iron gabion and fascines, being the kind chiefly used int he approaches against Fort Wagner:
Two hundred and seventy-nine pounds of hoops iron, .058 inch thick, Numbers 17 wire gauge.
One hundred and thirty iron rivets, flat-headed, Numbers 7 iron guage.
Fourteen stakes, 3 by 1 inches, and 9 feet long, weighing 14 pounds each.
Twenty fascines, 9 feet long and 9 inches in diameter, weighing 83 pounds each.
And a sufficient number of wedges to fasten them.
Total approximate weight of sap-roller, 2,200 pounds.