Popular science monthly . signals are used both at lilock sectionsand at interlocking plants and are operatedboth automatically and manually. In the opinion of Mr. Rudd, light signalsare the coming t>pe, and will supersede thepresent semaphore signals. The onlyalternative is the possibilit\ of an auto-matic speed-control sxsteni for trains, suffi-ciently reliable to preclude the necessity- forfixed signals of aru kind. Automatic Block Signals Additional Si9nal3 atInterlocking Planrt iiiiiiiill FVo<(«< CJwtO PTXMiSgrtMrrt Proteed Stop the* pfMccd Proceed. pr«»«rrt prt»
Popular science monthly . signals are used both at lilock sectionsand at interlocking plants and are operatedboth automatically and manually. In the opinion of Mr. Rudd, light signalsare the coming t>pe, and will supersede thepresent semaphore signals. The onlyalternative is the possibilit\ of an auto-matic speed-control sxsteni for trains, suffi-ciently reliable to preclude the necessity- forfixed signals of aru kind. Automatic Block Signals Additional Si9nal3 atInterlocking Planrt iiiiiiiill FVo<(«< CJwtO PTXMiSgrtMrrt Proteed Stop the* pfMccd Proceed. pr«»«rrt prt»«r«dtouo»ihort tow»*Mn«il «/tratn*r «k3irv«tiOA SiQA^I- 99Ul. Pioc c ett. pr« M r e d Rows of white lights corresponding with the positions of semaphore arms indicate all signals bothby day and by night. These new signals have been given the name of •position lights A Quick Method of Measuring Light The greater the size the greater the accuracy as a measur-ing instrument where this kind of a sphere is used. A one hundred inch sphin liui in. ur u td lui h^lit-testing work. A sight box, large pho-tometer-bar, movable comparison lamp and scale graduated in millimeters are essential elements THIS qiiccr-looking ai)|>aratiis, sugges-tive of the rind of some Brobdigna-gian watermelon, is de\oted to theinnocent purpose of measuring light. Wcsay rind advisedly, for the sphere ishollow. It is of a dark color on the outside,and, like the melon rind, white inside, butthere the similarity ends, for instead ofpulp and seeds one finds at the center ofthe sphere a whitened fixture designed tohold the electric lamp which is to be instrument is located at the NelaPark lal)orat<)r\-, in Cleveland. Light from the test lamji issues throughan opal window in the outer shell and fallson a comparison-screen. In the illustrationthis screen is being obser\ed by the younglady sitting at the left. Inside the longbox at her right is a sliding lam]) of knowncandlepower, agai
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1872
