[Diagram of solution.] Thru [sic] R pass plane PL // to the plane of the eyes. Draw a line from E#L# (which is nearer to F than E#R#) to F, cutting PL in O. Draw E#R#O; thru F pass a plane // to PL and crossing E#R#O in A. Thru A pass F' // F. F' and F are the positions of F to E#R# and E#L#. D. So it can be shown that 2 other eyes would see F in positions F and F''. .'. 4 eyes focused on R see F as F, F, F' and F''. D. FIG. 11. THE PATH OF A TACK. WORK DONE BY D AT AGE 11 YEARS. Discussion of the determination of the course of a freed tack, T, connected with other tacks by rubber bands. A. Fig. 1. [Diagram including points T, T'; band B; and ray L.] When connected to a tack T' by band B. Draw T[,] T'[,] or L. T freed will travel along L, answer. B. Fig. 2. [Diagram including points T, T', T''; bands B, B'; and ray L.] When connected to 2 tacks T' and T'' by 2 bands B and B'. Answer: Along L, the bisector of T' and TTT''. C. Fig. 3. [Diagram including points T, T', T''; band B; and ray L.] The same as B, but only 1 band B. Answer same as to B. D. Fig. 4. [Diagram including points T, T#1#, T', T''; and ray L.] When connected to 3 tacks by any number of bands. Draw T'T#1#, and treat as in B and C. D. SCHOOL HISTORY In the September following his ninth birthday D entered upon formal instruction in the junior high school. In the autumn following his tenth birthday he entered senior high school, from which he was graduated at the age of 12 years, with a scholastic record which won for him two scholarships. He was admitted to a large Eastern college at the age of 12 years 6 months (1922-1923), and made a superior record throughout the course. It was very interesting to see that D continued to discover means of obtaining social contacts in spite of the great difficulties due to his extreme youth and his intellectual deviation. Thus it is not easy to plan how a 12-year-old boy might successfully participate in college athletics when the median age of college freshmen is over 18 years, but this problem was not too difficult for D. He presented himself to compete for the post of coxswain on the freshmen crew where, other things, being equal, light weight is an advantage. He was graduated from college, with Phi Beta Kappa honors, in 1926, at the age of 16 years 2 months. At that time he was ambitious for a career in science. EDITOR'S SUPPLEMENT D undertook graduate work, with distinction, in the field of chemistry. He became an industrial chemist with an important position in the research phases of the motion-picture industry. Word has been received of his death in September, 1938.