conveying a different meaning: Those with a square end are "absolute" signals and generally force trains to stop when in their most restrictive position. Those with a pointed end are "permissive" signals and permit a train to continue at a significantly lower speed rather than having to come to a complete stop. Semaphores with a "fishtail" end (that is, a V-notch end) are "distant" signals conveying to the engineer what the aspect of the next signal is (as a forewarning). The color of the semaphore frequently matches the above categories as well, with absolute signals typically having a white stripe on a red blade and the others having a black stripe (most often repeating the shape of the blade's end) of either square or 60 degree, were the RSA Standard. Searchlight signals The 1911 patenting of the "Doublet-Lens" combination for long range (2,500 feet in daylight) by Dr. William Churchill at Corning Glass's research facility in Corning, New York, indicated the reign of the semaphore signal in railroad use was rapidly approaching its end. By 1916, this optical combination and a flagging sales response prompted the management of the Hall Signal Company to realize their just introduced and most advanced Style "L" semaphore mechanism (the very last produced by any U.S. signal company), was indeed obsolete. That dual lens device had been developed by Cornell University's Dr. William Churchill, while he was working at Corning Glass Works. He'd finished developing color standards for railroad glassware, which Corning had patented on October 10, 1905. They were immediately put to use as daylight short range and tunnel type electric incandescent bulb illuminated signals. He then turned his attention to medium and long range Daylight signals using the same incandescent electric lamps with greatly improved optics: the "Doublet-Lens" combination. Hall's response to this (for them) dire situation was to buy the 1918 filed patents from one Mr. Blake for his "Searchlight" signal. In reality, the searchlight signal was an updated and modernized variation of the old Hall enclosed disc signal. What Blake had done was to harness the standard railroad three position polarized vane relay, add a miniature spectacle and Pyrex, low expansion Borosilicate glass roundels, and couple that with a very efficient elliptical reflector and optical lens system with a very large 10-1/2 diameter stepped outer lens. This revolutionary development provided a signal with a visible indication of over a mile from