ly di- torium and employing an assistant who is liable to rect line, that is, as soon as the pivoted arm carrying give rise to trouble by confusing the pictures has often the trailing wheel again becomes parallel to the di- been found to be a serious drawback. The Gérard rection of motion of the… … used in a lecture are arranged A NEW PROJECTION SYSTEM FOR LECTURES, of a permanent memorial. His beforehand at the periphery of a idea of such a memorial is a wheel resembling a bicycle wheel. By means of a turns, the cam will move to the left of the vertical “magnificent water gate, the whole…
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