207. In the construction of floors it would be an advantage to make each girder only half the breadth given by the rule, and to limit the distance apart to 5 feet; to bridge the upper or floor joists over the girders, and notch the ceiling joists to the under-side of them; and to omit the binding joists. This method would greatly increase the strength and stiffness; and, in point of economy, it is decidedly preferable; only it requires a much greater depth of flooring.

208. As the strain is always greatest at the middle of the length of a girder, it would be well to avoid making mortises there, if possible, either for binding joists or for any other purpose; and the most straight-grained part of the beam should be at the under-side.

Timber girders should not be built into the wall, but an open space left round their ends, either by laying a flat stone over them, or by turning an arch to carry the Wall above.

Girders should be laid from 9 to 12 inches into the wall, according to the bearing.