30 



MILITARY COMMISSION TO EUROPE. 



SIEGE OPEEATIONS. 



Simple trench. — In easy soil, that can be worked by the shovel alone, the men are placed 4' 

 apart; when the pick is required, 3' apart; in very difficult soil, 2' apart. The communications 

 leading to the first jiarallel have the following jirofile : trench 3' deep at the berm, 8' to 9' wide 

 at bottom; parapet 4' high and 9' thick at base. This should be completed the first night. 

 Next day the first parallel receives the following dimensions : parapet, 4' high, 16' thick at base ; 

 trench, 9' wide at bottora in the clear, 3' deeiJ in front ; two steps, revetted with fascines, against 

 the berm slope, and one broad step on the reverse slope. 



As regards their appearance, when completed, saps are singh, douhle, or covered; with respect 

 to the mode of execution, they avejlying or sloiu. 



The single sap affords cover from one direction only ; the double sap, on both sides ; the 

 covered sap, on both sides and above; the latter is employed to give protection against a ricochet 

 fire, or when descending a slope, or when following along the foot of a hill. 



In the flying sap the gabions are all placed and filled simultaneously ; in the slow sap the 

 gabions are placed and filled one at a time. 



For each head of the slow sap 24 sappers are detailed and divided into 4 reliefs ; there is 1 

 non-commissioned officer with each relief, and 1 officer for every 2 reliefs. 



For each head of sap the following tools are necessary: 2 sap hooks, 9' long, as in annexed 

 sketch ; 



.+.jr. 



1 square; 1 arm 1' long, the other 18", as a measure for the 1st sapper; 3 measures for the 

 2d, 3d, and 4th sappers, respectively, 2', 2^', and 3' long; 4 hand axes, to cut turf and roots; 4 

 picks, or mattocks, according to the soil; 6 shovels; 2 axes; 1 tracing cord; 2 sap forks, each 

 5' long, as shown by the annexed sketch : 



1 seven-foot measure; 2 handspikes, 7' long, 6" square; 1 roller, 4' long, 18" in circumference; 

 1 block, 2' long, 6" square, as a fulcrum for the handspikes ; 1 curved wooden mallet, of the 

 shape and dimensions shown in the annexed figure, for driving down the crowning fascines, &c. : 



4' 6' 



For each head of sap the following materials are required : 1 sap roller ; sap gabions ; sap 

 fagots ; fascines ; stakes, 2^' long, for fastening the fascines ; sand bags. 



