When one beam is let in, at an inclination to the depth of another, so as to bear in the direction of the fibres of the beam that is cut, the depth of the cut at right angles to (he fibres should not be more than one-fifth of the length of the piece, the fibres of which, by their cohesion, resist the pressure.

To Compute the Length necessary to resist a given Horizontal Thrust, as in the Case of a Rafter let into a Tie-Beam.

- = l;b representing the breadth of the beam in inches, T the horlbc zontal thrust in lbs., c the cohesive resistance of the material in lbs. per square inch, and I the length in inches.