Manual of military engineering . ction may tend to draw^ the sparscloser together and not strain the lashing. The minimumdistance of the anchorages should be double the upper block of the tackle is hooked to a sling of rope orchain passed over the crutch. Sheers can, as a rule, be usedfor heavier weights than derricks, but can only move them in avertical plane passing between the legs. The feet of sheersmust be secured or let into holes in the ground. The distanceapart of the legs should not be more than one-third the lengthof the leg up to the crutch, and the sheers not to be heele
Manual of military engineering . ction may tend to draw^ the sparscloser together and not strain the lashing. The minimumdistance of the anchorages should be double the upper block of the tackle is hooked to a sling of rope orchain passed over the crutch. Sheers can, as a rule, be usedfor heavier weights than derricks, but can only move them in avertical plane passing between the legs. The feet of sheersmust be secured or let into holes in the ground. The distanceapart of the legs should not be more than one-third the lengthof the leg up to the crutch, and the sheers not to be heeledover more than one-fifth of their 282. The legs of the sheers are laid side by side on a skid, and lashing. j-ept 2 inches apart by a wedge. The lashing is commencedwith a clove hitch on one spar, carried six or more timesupwards round both spars without riding, then tw^o Trappingturns, and finished off w^ith two half hitches round the otherspar. (Figs. 1 and 2, PI. 74.) I*lcOte 74 Fi^.L USE OF SPARS Fry. 3. STveei^s
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