The illustration indicates the four principal stages in the construction of Schwickart's "Sun-Burst" prism, manufactured by the Universal Foundry Co., 283-287 Scholes st., Brooklyn. Beginning at the bottom the first section shows the interlocking bars, the second shows the loose glass prisms rising on these bars, the third shows the first application of the cement to hold the prisms in place, and the fourth or top section shows the finished construction. Fuller details will be given in the issue of January 9.