The major publications on the subject are reviewed briefly, with consideration of the degree of generality achieved. The fundamental equations of the general case are then derived by a short and simple analytical procedure, which leads to the recognition of the analogy between the moments at a joint and the ellipsoid of stress.
The general formulae are reduced by substitution to give the much smaller equations for a common case, and an example is worked out in full. The results of an investigation of the maximum stresses in a polygonal frame are presented graphically.
An experimental check of the analysis serves to provide a physical proof of the value of the formulae.