Experiment has shown that great strength may be given to masonry, in all the usual constructions on land and in water, by causing the pieces of the solid material itself to dovetail and bind together. Acting on the principle involved in the results thus produced, a London builder has proposed some new forms of stones, so contrived as to afford superior binding power from the fact that, when structurally put together, they are tied to one another in all directions. Each block is cut in such a shape that only four sides of it form a parallelogram, its upper and lower sides being formed each by two inclined planes, which incline towards each other from the edges towards the middle, in such a manner respectively, that the direction of the furrow that is formed by the two inclined planes of the one (upper) side forms a right angle with or crosses the direction of the other or lower side.