The question of the elastic strength of flat plates, supported or fixed at the edges, and subjected to uniform or concentrated loads upon their areas, is, from an engineering standpoint, one of the most unsatisfactory parts of mechanics; for exact solutions, rigorously based upon the laws of elasticity, have been obtained in only a few cases, chiefly for circular and elliptical forms.

Amongst practical engineers the confusion that exists on the subject is remarkable, for the author has, in the course of his inquiries, elicited the most contrary results. As a case in point, there seems no real knowledge whether rectangular and square plates should be ribbed along the diagonals or across the diameters. Again, as an instance of the doubt existing concerning the stress values in these plates, it may be mentioned that, in reply to an inquiry asking for help in this connection, a correspondent in the American Machinist, under date August 7, 1909, deplores the fact that he can obtain no assistance from English or American text-books and states that there is an entire absence of experimental data. Although the latter statement is not quite accurate, yet it can be confidently asserted that there have been very few experimental results recorded, and these few, for the most part, are not available in English.