set, along with the batteries to power it, was miniaturized to fit inside a shell, and its glass vacuum tubes designed to withstand the 20,000 g-force of being fired from a gun and 500 rotations per second in flight. Unlike normal radar, the proximity fuze sent out a continuous signal rather than short pulses. The NDRC created a special Section T chaired by Merle Tuve of the CIW, with Commander William S. Parsons as special assistant to Bush and liaison between the NDRC and the Navy's Bureau of Ordnance (BuOrd). One of CIW staff members that Tuve recruited to Section T in 1940 was James Van Allen. In April 1942, Bush placed Section T directly under the OSRD, and Parsons in charge. The research effort remained under Tuve but moved to the Johns Hopkins University's Applied Physics Laboratory (APL), where Parsons was BuOrd's representative. In August 1942, a live firing test was conducted with the newly commissioned cruiser ; three pilotless drones were shot down in succession. To preserve the secret of the proximity fuze, its use was initially permitted only over water, where a dud round could not fall into enemy hands. In late 1943, the Army obtained permission to use the weapon over land. The proximity fuze proved particularly effective against the V-1 flying bomb over England, and later Antwerp, in 1944. A version was also developed for use with howitzers against ground targets. Bush met with the Joint Chiefs of Staff in October 1944 to press for its use, arguing that the Germans would be unable to copy and produce it before the war was over. Eventually, the Joint Chiefs agreed to allow its employment from December 25. In response to the German Ardennes Offensive on December 16, 1944, the immediate use of the proximity fuze was authorized, and it went into action with deadly effect. By the end of 1944, proximity fuzes were coming off the production lines at the rate of 40,000 per day. "If one looks at the proximity fuze program as a whole," historian James Phinney Baxter III wrote, "the magnitude and complexity of the effort rank it among the three or four most extraordinary scientific achievements of the war." The German V-1 flying bomb demonstrated a serious omission in OSRD's portfolio: guided missiles. While the OSRD had some success developing unguided rockets, it had nothing comparable to the V-1, the V-2 or