The art of projecting. A manual of experimentation in physics, chemistry, and natural history with the porte lumiere and magic lantern. (1892)
Dolbear, A. E. · Lee and Shepard · leaf 87
s in unison, turn the second fork so that it vibrates horizontally. Adjust the light so that it falls upon the second mirror as before, and thence to the middle of the screen. Now, if both forks be struck, the resulting figure may be a straight line, an ellipse, or a circle depending upon the phase… … CirC ♦ upon the screen, swing the second forWh^ugh a small arc, and the circle will be drawn ouN$to a luminous scroll, (Fig. 51). If the forks are
Light · Magic Lantern
Internet Archive · Public domain (published before 1931). Free to use for anything.
