This section is from the book "A Practical Treatise On The Joints Made And Used By Builders", by Wyvill J. Christy. Also available from Amazon: Practical treatise on the joints made and used by builders.
This usually radiates. In the so-called French or Dutch arch, however, which is only to be tolerated when built in cement, the joints run parallel to the skewbacks. Straight arches have nearly flat soffits and quite flat backs, and their joints radiate to the apex of an equilateral triangle of which the soffit forms the base. They are safe with a wrought chimney bar with bent ends below them for support. A gauged arch is one formed with cut and rubbed bricks set in putty, by which very fine joints are obtained not exceeding -1/8- inch in thickness, and all accurately radiating to a centre. This kind has a slight camber amounting sometimes to more than an inch per foot of span. The joints of relieving and other rough arches, as well as all those which are turned with ordinary bricks, are wider at the back than at the soffit and are usually turned in half-brick rings, but where through the curves being quick the joints are much wider at the extrados they can be packed with pieces of tile or slate. When turning arches in half-brick rings the first ring requires thin joints, the next thicker, and so on, in order to prevent the rings separating at the collar joints when settling, and where the joints of the rings coincide headers may be built in to form a bond between the rings.
Asphalte Joint is a contrivance for keeping out damp, and is made by applying a layer of hot tough asphalte from § inch to ½ inch thick along the top of a course. A good plan in important works is to only half flush the joints at the damp course with mortar, then pour in the asphalte and lay the next course of bricks hot, after which half flush with asphalte. If the walls of a building are not covered by the roof, a damp course is often as much needed at the top as at the bottom. Asphalted felt is used as a seating or bearing for wood or ironwork on stone templates, and is found advantageous in checking vibratory motion produced by percussion.
Back Joint is a joint parallel to the face of the work or any inside vertical joint that is not a cross or transverse one. In footings it should be always kept as far from the face as possible.
This is one kind of pat or tuck-and-pat joint, and results from a description of pointing, which differs considerably, however, from common tuck pointing. Whilst the latter consists of very narrow sham white joints of pure white lime putty projecting from a wall face which has been brought by rubbing and colouring to one uniform colour, bastard tuck pointing is produced by forming on the ordinary stopping a projecting ridge about 3/8 inch wide, having clean cut and parallel edges, and which is not pure white like the other, but of the same colour as those parts of the joints that do not project.
Bead Joint occurs occasionally in brickwork, and is formed by finishing off the pointing stuff with a projecting convex surface in lieu of a square-edged ridge.