National Geographic : 1936 Nov
AN c"X RAY ON WHEELS" DETECTS "RAIL CANCER" Rails develop internal fissures invisible to the inspector's eye. In past years these were frequent causes of derailment. Now railroads employ Sperry detector cars to check these defects. While the car runs, brushes contact the rails and record imperfections by electrical impulses. These impulses are amplified to operate the pen which here is marking the record tape, and also to spray white paint on the rail at the defective spot. rnotograpn DyJ.isaylor KoDerts PULLING AN IMAGINARY LOAD THAT GOES NOWHERE This test-plant locomotiveatPurdue University is"running" onrevolving wheels, visible below, and the "pull" iscontrolled bythelarge, lowwheels beneath the platform wherethe man stands. Purdue was apioneer inestab lishing a locomotive testingplant and here seniors and graduate students of railway engineering problems dolaboratory work. Forty years agotheUni versity first experimented with wind resistance and streamlining.