The destructive effect of grenades and Coehorn shells charged with high explosives will doubtless in many cases check or stop the advance of saps and trenches, and necessitate the use of blinded approaches or mining-galleries in stubbornly contested sieges. The successful application of mines at Géok Tépé will doubtless lead to their future employment under similar circumstances. In the close attack upon a shielded casemate or disappearing turret their use seems a necessity, and when these defences are founded on rock or massive concrete foundations, tunnelling operations by drilling and blasting will be required. When practicable they will be expedited by the use of power-drills driven by electricity.
It seems hardly necessary to add, that in sapping and mining operations, as in all other branches of military engineering, all new and improved inventions and methods which are applicable to the work on hand will be used, as a matter of course.
The thickness of cover given in the text is based upon the penetrations of the hostile projectiles.
For ready reference the maximum penetrations obtained in experimental firing up to this date (1894) are given herewith, viz.:
Service bullets, copper or German-silver jacket, of 6.5 to 8 mm. calibre, initial velocity from 2000 to 2550 f. s.:
| At Muzzle. Inches. | 100 yds. Inches. | 900 yds. Inches. | 2000 yds. Inches. | 2730 yds. Inches. | |
|---|---|---|---|---|---|
| Pine wood | 30 to 50 | 31 to 35 | 10 to 14 | 4.4 | |
| Seasoned oak wood | 4 to 8 | 1.18 | |||
| Untamped clay | 60 to 78 | ||||
| Light sand | 8 | At 500 yds....17 inches. | |||
| 330 yds. Inches. | 440 yds. Inches. | 880 yds. Inches. | 2000 yds. Inches. | ||
| Sand and earth | 36 | 33 | 20 | 14 | 4 |
| Steel and iron plate | 0.31 to 0.38 | 0.28 | 0.24 | ||
| Brick masonry | 4½ | ||||
| Ice | 63 | ||||
| Special steel-coated bullets, cal. 0.26 and 0.30: | |||||
| Pine wood | 55 | ||||
| Oak wood, seasoned | 16 to 24 | ||||
| Beech wood | 23 to 30 | ||||
| Sand | 14 | ||||
| Special steel-coated bullets, cal. 0.236, vel. 2600 f. s. | |||||
| Pine wood | 62 | ||||
French authorities give a muzzle penetration of 12 mm. = 0´´.473 in iron plates for the Lebel bullet. No published experiments confirm this.
But few experiments seem to have been made to determine the penetration of the projectile of field and siege guns into earth, and the published data are very meagre and unsatisfactory.
The German Engineer’s Handbook (Pionier Taschenbuch, 1892) prescribes the following thicknesses of parapets for cover against small-arm and cannon fire, viz.:
| Material. | Shrapnel and Splinters. | Small Arm. | Field-guns. | Siege-guns. |
|---|---|---|---|---|
| Earth, sandy | 30" | 20" to 40" | 16½' | 23' |
| Turf and marshy earth | 60" | |||
| Wood | 34" to 40" | |||
| Brick masonry | 15" | |||
| Brick masonry, single shot | 3' 4" | |||
| Two steel plates each 0.32" | 0.64" | |||
| Packed snow | 6' | 26' | ||
| Sheaves of grain | 16½' |