A list of diameters of rivets to be used with boiler plates of given thickness is here presented. The diameter of the rivet may equal 1.2 times the square root of the thickness of the riveted plate. On this basis the following is a list such as is required - 5/16-in- plate, 13/16 in. diameter; 3/8-in. plate, 3/4 in. diameter; 7/16im plate, 13/16 in. diameter; 1/2 in. plate, 7/8in. diameter; 5/8-in. plate, 15/16 in. diameter; 3/4-in. plate, 11/16 in. diameter; 7/8-in. plate, 1 1/8in. diameter; and 1-in. plate, 1 1/4in. diameter. The following has been given as the practice of Lancashire boilermakers. For 3/8-in. and 7/16-in. plates, 3/4in. diameter; for 1/2-in. and 9/16-in. plates, 13/16 in. diameter; for 11/16-m. and 5/8-in. plates, 7/8in. diameter; and for 3/4-in. and 1-in. plates, 15/16 in. diameter.