We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
148 RICHARDSON'S BLUEBOOK OF .PROJECTION
set. Men must have room to work around a set if it is to be well taken care of. Install a drop light (preferably a reel light) on a long cord so that the projectionist may be able to illuminate any part of the machine without difficulty.
A thick layer of cork or rubber absorbs vibration for a time, but with the passage of time these substances lost a part if not all of their resiliency. (65) Were we considering the installation of a motor-generator set in a theatre of our own, we would set it on coil springs not less than six inches long, and of such capacity that four of them, one under each corner, would carry the weight with no more than one inch depression. Coil spring supports are not expensive. Any responsible spring manufacturer will supply them. Order four. springs that will carry the weight of the set and he will guarantee sufficient resiliency to absorb all vibration.
It is necessary to make a strong concrete base of proper depth and size and sufficiently massive, with a half-inch bolt embedded head down near each corner and protruding about one and one-half inches above the surface. The springs themselves should consist of a spiral of from four to five inches diameter at one end, tapering to about two and one-half inches at the other, the extreme small diameter of the steel being turned in to the axis of the spring and curled to take a half-inch bolt readily.
The smaller end of the spring is then bolted to the bottom of a wooden frame on which the motor-generator set is to rest, or directly to the bottom of the cast iron or steel base of the set. The larger ends of the springs are attached to the ends of the imbedded bolts. The taper of these springs gives the assembly more stability than would be had were they cylindrical, without at all decreasing their action. With such an arrangement (which sounds complicated but is very simple and low in price) we will guarantee despite the fears of many exhibitors that neither vibration or sound will be communicated tc the building.
If the manufacturer of the set, or the contractor who