Chav. VIII.
*167
the facing ; no stone should contain less in its bed than 4 superficial feet, and should be ofa size to break joint at least a foot with the stones adjoining.
“ Freestone masonry of piers and abutments should be laid in alternate courses of headersand stretchers ; the headers not to present an outside face of less than 2 feet, and all toextend at least 3 feet in length into the body of the work; the stretchers not less than3 feet in length, and in breadth 2 feet on the bed.
“ No stone used in the interior of the work to have less than 4 superficial feet on its bed,
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Fig. AGO.
GLASGOW BRIDGE ; VLAN OK PIER.
and to be of the same thickness as the courses on the outside. The whole to be square
dressed throughout, to be laid on its natural bed, Hushed in with good lime mortar usedfresh, and of a quality that will harden under water.
“ Arch-stones or voussoirs must be of the dimensions designed, and should break joint withthe adjoining stones at least 1 foot; their beds should be truly radiated, chisel draftedround the edges, and neatly picked dressed within the drafts. The soffite faces neatly
Fig.470.
GLASGOW BRIDGE.
broached in horizontal to the beds, all each
stone down to its place with a wooden maul.
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Safes
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Fig. 471.
SECTION OP ARCH OP GLASGOW BRIDGE.
“ Spandrill facing , if of granite masonry, to have its stretchers 12 inches on the bed, andone fourth of each course made headers, passing at least 1 foot 9 inches into the solid wall,no course being less than 14 inches in height, the courses beneath generally being made
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