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.
Saddle Joint is the outcome of the operation known as saddling the joint, which consists in not weathering the stones of a cornice or coping quite up to the joints, but leaving them at their full height at each end, so as to form a small weathered ridge or saddle to throw off the rain, as shown in Fig. 21. This kind of finish is further noticed under Vertical Joint. A stone cut with two skewbacks to form a double springer on the top of a pier, as in Fig. 22, for the support of two opposite arches, is sometimes called a saddle piece, and the continuous joint between such stone and the overlying masonry is another form of saddle joint.
Sawn Joint occurs in flagging and elsewhere between stones when no other labour besides sawing is executed on the sides or surfaces forming the joint.
This is an exactly similar joint to that of the joiner of identical name, and occurs where stone cornices and mouldings run into and unite with corresponding ornamentation in cast iron, which happens in bridge work and other situations.
Shift Joint is the same as described in the Bricklayers' Section.
Side Joint in ashlar is a vertical cross joint usually simply called joint, and is worked like the bed. In ashlar facing it requires strengthening with copper or gunmetal cramps or dowels. Iron cramps enveloped in tar form a cheap but hazardous substitute, excepting in unimportant work or, perhaps, when cast or galvanised. In coursed rub-ble masonry the side joints ought to be dressed square and true, or free of twist; and in squared, snecked, or irregular coursed rubble they are usually roughly squared, and show mortar spaces of varying thickness. In random rubble they follow almost any direction, but are so disposed as to break joint against both the upper and lower blocks. Amongst masons the term "side" often gives place to "end."
Smooth Joint is the result of carefully axing, tooling, chiselling, or dressing the surfaces of contact and finally rubbing them with stone, sand, and water, to a degree of exactness and fineness that cannot be surpassed without losing what little key remains for the adherence of mortar.
One that is perpendicular to the face and bed or axis of the same block, or to the principal face or facial plane of the feature of which the joint is a factor. For instance, in a traceried window all the joints should be square to the axes of their respective bars, transoms, jambs, mullions, etc, and to the window plane as well. To be square, the surface of a joint must be out of winding. A rusticated joint is said to be square when formed with a rectangular groove.