Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

577 OF ENOINEERING F0RMULÆ. N.B.—The thickness of the superior slope, to resist heavy rifled ordnance, must not be less than 25 feet. . The Enfield bullet penetrates 11J inches in elm-wood planks at 50 yards. Ranges from 100 to 200 yards. Enfield rifle.. Armstrong. . P3 /■ ’ w “IS® M - : : : : : : : : : Sand-bags 12" 6-pr. 9-pr. 12-pr, 18’24-pr. 12-pr. 20-pr. 40-pr. 70-pr. V Guns. lbs. 2 3 4 6-8 1-5 2-5 5 ■ 2 Charge. 3" 18" | 4" Illi 1 =5 “ ? h hJ § 1 a feet. 4 7 10 12-15 4-5 11 14-15' 15-16 21 gtu ins. 37 40 45 50 _g 3-4 j At 50 yards. 6 9 12 18-22 8 15 18 20 25 Ordinary 1 Thickness of Parapet । required. Earths. Very wet.. 0'87 Sand and clay 1 • 09 Stiff clay .. 1 • 44 Light earth I-50 Ditto when 1 recently >1*9 turned ) Woods. Beech .. ) , Ash .. .. f Elm .. .. 1-3 Fir .. .. 1-8 Poplar .. 2 Multipliers for Penetration in other Eartha and Woods. Penetration of Projectiles. Required thickness of Parapet, &c. (Capt. Bridges, R.A.)