Development, undertook to launch a full-scale effort to develop atomic bombs. As the scale of the project became clearer, it came under direct military control as the Manhattan Project. World War II Briggs sought new business for the Bureau. In 1939 he sent Secretary of Commerce Daniel C. Roper a list of services the Bureau could provide in the event of armed conflict in Europe. By 1942 90% of the Bureau's activities were classified work for the war effort. Some of the Bureau's activities were the non-rotating proximity fuze, guided missile developments (see the Bat), establishment of a Radio Propagation Laboratory, critical materials research on optical glass which Germany had previously supplied, on quartz and synthetic rubber and measurement and calibration services. Briggs changed the Bureau's culture from one of open access to one of secrecy. Briggs retired from the Bureau in 1945, at the age of 72. He was appointed director emeritus of NBS after working for 49 years in federal government. Bureau employees erected a bronze sundial in his honor through their Employees Welfare Association. At his request the names of the first three directors of Bureau are cast onto the rim of the instrument: Samuel Wesley Stratton, George Kimball Burgess, and Lyman James Briggs. In 1948 Briggs received the Medal of Merit from US President Harry Truman for his distinguished work in connection with World War II. At the request of Secretary of Commerce Henry A. Wallace, he wrote a 180-page account on NBS war research that was published in 1949. Later life In his retirement Briggs returned to research, establishing a laboratory for studying fluids under negative pressure at the National Bureau of Standards. This topic was directly related to his earlier research in the water uptake of plants. In one famous experiment he measured the negative pressure (or tension) that would break a column of water held in a capillary tube by capillary action. It turned out that at room temperature the maximum attainable tension in water was 250 bar and in mercury nearly 500 bar. This finding was published in several papers between (1950–1953), and the 1950 paper remains a classic and is still regularly cited in the literature on metastable water. Briggs' love for baseball triggered another piece of research. During World War II the government had mandated that rubber in baseballs be replaced by cork. Complaints about the new balls led Briggs