A reliable chain is made of the treble best Staffordshire scrap iron.
Crane and pulley chains should be made with the shortest link possible, according to the diameter of the iron used, as there is a considerable leverage exerted on a long link when running round a pulley, more especially where the diameter of the pulley is small.
A Slater’s Truss.—Slaters’ trusses ([fig. 102]) are used in pairs by slaters and tilers when laying their material. Boards are laid across the trusses and form an effective platform on which the workman can kneel without damage to that part of the roof already covered. They are slung from the ridge or other suitable fixture, and can be pulled higher as the work proceeds. An old sack or similar material laid under the truss will prevent any possible damage during the progress of the work.
Fig. 102
Duck Runs.—Duck runs ([fig. 103]) are laid upon slate and tile roofs to give footing to, and to prevent damage being done by, the workmen.
They should be firmly fixed, either by slinging from the ridge or butting against a solid resistance.
Fig. 103
Mortar Boards.—A mortar board is used as a bed on which mortar can be mixed or deposited. It is roughly made of four or five 9-inch boards each 3 or 4 feet long, framed together on the under side. Their use prevents the new mortar coming in contact with the scaffold boards with an injurious effect.