SAP. 



SAPPERS AND MINERS, ROYAL. 



274 



SAP a a mode of executing the trenches at the siege of a fortress, 

 when the besiegers arrive within such a distance from the covered- 



, it the fire from thence becomes too dangerous to allow the men 

 to work on the ground without being protected by some covering 

 objects, as gabions, placed between themselves and the enemy. 



The process of sapping varies with the distance from the worts of 

 the fortress and the degree x of activity with which the fire of the 

 defenders is kept up. It is, therefore, divided into what is called the 



tp and the complete or foil sap. In ordinary circumstances, in 



'sieges, before the introduction of rifled ordnance or rifles to any great 



extent, the flying sap began to be used in forming the second parallel 



trench, which may be about 320 yards from the covered-way ; and it is 



executed in the following manner. 



If the distance from the depot of siege-materials to the place of 

 the intended trench is not too great, every man carries two gabions, 

 one on each side of him, or both slung at his back ; he carries also a 

 pickaxe and a spade, and in the first case these are fixed in the gabions, 

 l.ut in the latter he carries them in his hands. If the distance which the 

 working party has to march is considerable, this burden would be too 

 fatiguing, and then each man carries on his shoulder one gabion toge- 

 ther with a pickaxe or a spade. Carrying the gabions one on each 

 ride has the advantage of permitting the man to carry his musket 

 slung. The work is begun at night, and when the sappers have arrived 

 at the ground where the tracing-line for the intended trench has been 

 laid down, they set up their gabions a few inches in front of that tracing- 

 line, the officers observing that the row of gabions in its whole length 

 is correctly placed. The portion of trench to be executed by each 

 sapper, or workman, is equal in length to the space covered by two 

 gabions (about 4 feet) : the men sit down or otherwise keep themselves 

 covered till the order is given to commence digging, and when the 

 number of men who constitute the working party is greater than 

 suffices to allow one man to every two gabions, those who have not 

 room to work retire to a little distance till they arc required to relieve 

 tli. ..there. A man may fill his two gabions with earth in about a 

 quarter of an hour, and then they will be proof against a musket 



. except at the place where they touch each other ; after this the 

 earth obtained in executing the trench is thrown beyond the gabions 

 towards the fortress. During the progress of the work the gabions 



i shed a little way outwards at the top, in order that they may 

 illy resist the pressure of the earth which they are to retain ; 

 ;iml they are sometimes crowned by two or three rows of fascines 

 which are laid upon them in a direction parallel to the trench. 



If the work proceeds by day and night, the parties are relieved 

 ( v.-ry eight hours ; and a trench executed by flying sap may, in soil of 

 medium tenacity, be completed by three reliefs of men. 



U hen the approaches of the besiegers have advanced so near the 

 covered-way that the fire of the defenders will no longer permit the 

 men to bring the gabions openly to the ground, the full sap is prac- 

 tised. For this purpose the sappers are divided into brigades of eight 

 men each ; and of these a denii brigade only of four men is employed 

 in the formation of a single line of trench. The party is provided with 

 a mantelet (a plate of iron thick enough to IK- musket-proof, and 

 capable of being moved forward by being mounted on small wheels) by 

 which the men may be covered in front ; or, instead of this machine, 

 there is provided for the same purpose a great gabion called a sap- 

 roller. This is a cylinder of banket-work, feet lung, and about 4 feet 

 diameter, and having within it a gabion of equal length, but about 

 2 feet six inches diameter ; the ax. . gabions are coincident, 



and the space between the exterior of the one and the interior of the 

 other is stuffed with fascines, by which means it is rendered musket- 

 proof. The sap-roller turning on its convex surface is found to be 

 more manageable than the mantelet ; and when it is intended to form 

 a trench in any proposed direction, by breaking out from one which 

 has been already executed, it is raised over the parapet of the latter 

 trench, and gradually low. r. d ..11 the exterior side, being guided l.y 

 means of a hook, so that it may have a position perpendicular to the 



t tlic intended ti leading sapper of the dcmi-brigade 



.nts through the parai>et, and pushing the sap-roller forward 

 about 2 feet, he hastily places an empty gabion in rear of that extre- 

 mity of the sap-roller which is ne.-ire.~t to tin- enemy's work, in order 

 that he may be cove > flank : then kneeling !>e!iind the 



gabinn, he excavates a : a treneli, IS inches wide, and as 



many in depth, leaving a beruie. al>ut I '2 inches broad between the 

 gabion and the nearest edge of the excavation, ami throwing the earth 

 into the gabion. When dug, the sap-roller is advanced 



;ib">ut 2 feet farther, and another gabion is set up in its rear, adjacent 

 to the former, and in the lii i ndl trench; a short fascine 



or two sand-bags (bags full of earth), are placed ime above another in 

 the hollow between the two gab'n i musket-ball may 



not be able to penetrate through the screen in that part. The sapper 

 then excavates as bef. 'to second gabion, a third 



is handed to him, which he places and fills as he continues to advance. 

 The second sapper of the s.|uad follows the first, keeping a little way 

 in his rear, and increases the width only of the trench by 20 inches on 

 the side which is farthest from the line of gabions, and he also throws 

 the earth into and beyond the gabions. The third sapper follows, and 

 increases the depth only by 18 inches on a breadth of 20 inches 

 measured from the rear side of the trench towards the gabions ; and 

 ABTS A5D KX. DFV. VOL. VII. 



the fourth sapper excavates a portion 3 feet deep, increasing the 

 breadth of the trench towards the rear by 10 inches. By this arrange- 

 ment the tasks of the different men are rendered nearly equal, and 

 complete cover is obtained when the work of the third man is executed. 

 The four men thus form a trench 4 feet wide and 3 feet deep, and a 

 step is left on the side nearest to the gabions for convenience in 

 standing to fire over the parapet. The working parties from the 

 infantry of the line afterwards complete the trench by increasing the 

 width to its usual extent, about 12 feet. 



Since the head sapper has the most dangerous post, the second, 

 third, and fourth sappers relieve him by alternately taking his place ; 

 and the work advances about 8 or 10 feet per hour, according to the 

 tenacity of the earth. 



If the fire of the place should be considerably subdued by the 

 action of the besiegers' batteries, the full and flying sap may be com- 

 bined in order to expedite the approaches. Thus a party of sappers 

 advancing on their hands and knees, and rolling gabions before them, 

 on .".rriving at convenient places set up the latter in line ; then two or 

 three men, at 'certain intervals from each other, dig pits behind the 

 gabions, in order to get cover, and afterwards work towards each other, 

 making a small trench, and filling the gabions with earth. The trench 

 may subsequently be made of the required width. 



When the distance to be passed over to the work attached becomes 

 very small, the angle formed by the adjacent zig-zags becomes very 

 small, or rather when 100 yards of the zig-zag does not carry the 

 approaches so much as 32 yards in advance (those being the propor- 

 tionate rates at which the single and double sap can be executed), then 

 the line of trench is carried on directly towards the place, sometimes by 

 a simple trench with traverses at intervals, and sometimes by what is 

 called the double sap. This is performed by two squads or demi- 

 brigades, who work parallel to each other, each being covered in front 

 by its own sap-roller, and there is a third roller in rear of the small 

 interval between the others. A row of gabions is placed on the right 

 of the trench executed by one squad, and on the left of that which is 

 executed by the other ; the distances between the rows of gabions is 

 about twelve feet, and traverses are formed in the trench at intervals 

 as the work advances. These project alternately from opposite sides; 

 so as to leave a serpentine passage along the trench. Hence this is 

 termed the serpentine sap. There is however another form of double 

 sap, called Jcbb's, or the double direct sap, which is now adopted in the 

 English service. This is formed by three brigades of sappers with four 

 sap rollers in front. The three brigades work parallel to one another, 

 and drive three saps straight forward. Traverses are formed as the sap 

 proceeds, projecting alternately from each side like teeth and over- 

 lapping one another. The intermediate space is then excavated, and a 

 covered passage is thus obtained. The distance between the parapets 

 on each side is 22 feet, or the breadth of eleven gabions. 



SAP-GREEN, a pigment, prepared by evaporating the juice of the 

 berries of the Khamnus cathartirus, or buckthorn, to dryness, mixed 

 with lime. It is soluble in water, less so in alcohol, and insoluble in 

 ether and oils. Acids redden it ; but the alkalies and alkaline earths 

 restore the green colour. [COLOURING MATTERS.] 



SAPOOENIN. [Kt.cui.tc Acin.] ' 



SAPONIC ACID. [Esci-Lic ACID.] 



SAPONIFICATION. [FATTY ACIDS.] 



SAPONIN. (Cj.HjoO,, ?) A colourless non-crystalline body, found 

 in the soapwort (Saponarla oficinalii) and many other plants. The 

 ieneguin of Oehlen appears also to be identical with this substance. 

 Saponin is extracted from the root of the soapwort by boiling alcohol 

 from which it is deposited on cooling. It is inodorous, tastes at first 

 sweet, then astringent, and finally acrid. It is soluble in water in all 

 proportions, forming a remarkably saponaceous solution. It is almost 

 insoluble in ether and in absolute alcohol, but readily dissolves in 

 dilute alcohol. Lime-water does not precipitate aqueous solutions of 

 Miponin. Intnxluccd into the nostrils a very minute quantity of 

 powdered saponin occasions violent sneezing. [EscoLic ACID.] 



SAPPAN WOOD. [BRAZIL WOOD.] 



SAI'I'KUS AND MINEHS, ROYAL, formerly the name given to 

 the non-commissioned officers and privates of the corps of Royal 

 Engineers. The men and officers are now collectively termed the 

 Koy.-d Engineers, but in specifying any individual private he is termed 

 sapper of the company of Itoyal Engineer-.. They are employed in 

 building and repairing permanent fortifications, in raising field- 

 redoubts and batteries, in making gabions and fascines, in digging 

 trenches [SAP], and executing galleries of mines during sieges, and 

 also in forming bridges of rafts, boats, and pout . 



The troops belonging to the department of the engineers were first 

 embodied at the termination of the war between Great Britain and her 

 American colonies, and they then received the designation of Royal 

 Military Artificers. The duke of Richmond, who was .it that time 

 master-general of the ordnance, formed them into independent com- 

 panies, and caused them to be stationed chiefly at Portsmouth, Ply- 

 mouth, Chatham, Dover, and Gibraltar. In the year 1807 the 

 Military Artificers constituted a corps of 32 companies, each consist- 

 ing of 126 men ; and a sub-lieutenant was attached to each company, 

 which was placed under any senior captain of engineers who might 

 happen to be where the company was stationed. But the want of a 

 proper organisation, and of officers permanently attached to the troops, 



