RECENT research in steel structures has demonstrated that the usual assumption of pin joints fails to predict with any approximation to accuracy the stresses in a framework,
especially in the case of stanchions; and it is not too much to say that the publication of the Reports of the Steel Structures Research Committee shows that any further advance in design must depend upon the recognition of rigidity or semi-rigidity
in the connections. Development of the mathematical analysis of the rigid frame has led to the conclusion that the exact solution to the problem is one of great complexity. So much so, that repeated attempts have been made to popularise the experimental or model methods of Professor Begg, in which a solution is obtained by measurements made on a small-scale celluloid model representing the ultimate frame.