When fire trenches are to be occupied for any length of time it is necessary to revet them. By that I mean the walls, and especially front walls, have to be faced or strengthened by sand bags, boards, corrugated iron or other material that is needed. This work to be of any use at all must have solid foundations and be thorough from top to bottom. Careless revetment work is of no use and a source of endless labor and trouble. All such work should be supervised by officers or N. C. O.’s who have a thorough understanding of such things, and they will be amply repaid if they take an active part in the work with their own hands. There are several forms of revetment, according to the materials available and the conditions of the walls to be revetted, but the usual materials are the sandbags, corrugated iron, stakes, boards, wire netting, etc., and these can be used either separately or in a combination. All these materials are generally kept in engineer dumps, some little way behind the firing line. Requisitions are made during the day by the officer commanding the sector of trench which requires revetting, and at night the men are detailed in carrying parties to go down to the engineer dumps and carry these things up for work the next day. SANDBAGS. Sandbags are usually available in large quantities, but it is well to remember that generally only half the number indented for reach the indentor. The rest generally go around the men’s feet and legs to keep them warm at night, and very often are used as a sort of mattress in the dugouts. This should not be allowed as it creates a tremendous wastage. The sandbags should only be about three-quarters filled, thus allowing for the choke or neck end, after tied, being turned under the back when laid in position. This also gives something to catch hold of when laying and brings the weight to something manageable, about sixty pounds. A bag three-quarters filled measures approximately 20″ x 10″ x 5″. Laid sand bags are called headers, when laid with bottom of the bag facing the center of the trench, and stretchers, if laid with the side facing the trench as per sketch. The neck end should always be tucked well in the bag in the case of the stretcher; the side seam, which is a weak spot in the sandbag, should be kept from exposure, that is, should be turned from the center of the trench.