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.
As will be gathered from the last paragraph, this is the antithesis of a straight joint, and equally necessary in masonry for appearance and strength, excepting, however, at the beds, where custom and convenience connive at long straight unbroken ones. It is obtained by setting each block so that its side, or end, or back does not fall in the same vertical plane as that of the back or joint of a block in the course below, but jets beyond or falls short of it by a few inches, or as much as circumstances will allow.
Butt Joint occurs amongst other positions when circular earthenware, or stoneware flue pipes, or vent linings are built in a stone wall with their ends butting. In tracery, fret work, columniation, etc, the butt joint is of common occurrence, and is frequently strengthened with a dowel.
The joints of reservoir walls are rendered water-tight by driving into them iron cement or other approved substance with the caulking tool and hammer. In building in ironwork with caulkings, as explained in the Smiths' Section, the mason must be careful that it is sufficiently protected not to injure the work by its oxidation, or to disfigure it with stains.
When this occurs in masonry, it is generally understood to be made with Portland cement, which is stronger neat than when gauged with sand, which reduces its tensile and compressive power. It is, however, most usually compounded of one or two parts of cement to one part of sand, quite free from impurity. Coping, chain bond, cramps, and dowels are commonly set in it. It is particularly necessary that masonry exposed to the action of the sea should be carried up with quick-setting cement immediately it reaches the mean sea-level, and it has been suggested that, in running water, the stronger but slow-setting Portland might be advantageously pointed with the weaker but quick-setting Roman or black cement. In mending stone, masons use a cement made of two parts of resin and one part of beeswax, which are melted together in a crucible over the fire and then poured into cold water, worked up well together and formed into sticks. The broken surfaces being well heated with a hot iron, the cement is melted and spread over them, and the joint completed by pressing them hard against each other. For soft stones, red shellac dissolved in naphtha, brought to the consistency of thick glue and spread over both surfaces, suffices, but a small dowel previously fitted makes a stronger joint. For inside work, plaster of Paris mixed up thin with a little dust of the stone is often used for the same purpose, the surfaces being first wetted.
Chamfered Joint is found in rustic work when the arrises of the blocks are bevelled off to edges forming an angular groove, as shown in Fig. 12, whose sides stand at right angles to each other.
This is synonymous with rebated joint.