by which an image is retained after circular lines by radial lines which intersect the middle the object by which it was formed has disappeared, A PRODUCES B. circular line at equidistant points separated by spaces, are due the phenomena here described and _illus- each having five times the width… … being shaded. instrument above re- DAA, To lay out the figure, from the cen- ferred to, and is Fig. 1-THE ANORTHOSCOPE. ter C, strike a circle bounding the adapted to experi- ments other than periphery of the disk, draw a diame- those belonging to the original apparatus. This instru- trical line,…
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