Reflection of Particles
   From the 1881 catalogue of James W. Queen of Philadelphia: "Apparatus to Illustrate the Reflexion of Motion. Consisting of a semicircular table of cherry, a marble slab for reflector, a spring pistol, ivory ball, and pocket to catch the ball after the rebound. Edge of table graduated to show the relation between the angles of incidence and reflexion. ... $20.00 ."

   The apparatus above is in the Garland Collection of Classical Physics Apparatus at Vanderbilt University. The note in the reference also illustrates two very similar pieces of apparatus: John Tyndall's demonstration to show the specular reflection of visible light, and his apparatus for showing the specular reflection of sound. It seems that when introducing students to specular reflection, a particle model describes the situation well. Newton thought so, too.

   The apparatus below is at Colby College in Waterville, Maine.

   REF: Thomas B. Greenslade, Jr., "Nineteenth Century Textbook Illustrations XXXIII: Reflection Spectrometers", Phys. Teach., 18, 143-4 (1980)
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