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.
372 RICHARDSON'S BLUEBOOK OF PROJECTION
sions. Second, as compared with types from which light is collected by a thick heavily-curved double-lens condenser, the loss through reflection and absorption is almost negligible. Third, the mirror collects a very large angle of light — that is, a very large percentage of the total light.
(88) The total light production varies with varying amperage, carbon trim, etc., (89) but averages about 165 candle power per square mm of crater floor area. This figure applies to the low intensity arc only. (90) With carbon trims in right relation to the amperage, current flow may vary from a low of 12 amperes to a high of 50 though motion picture projection seldom requires more than 30 amperes.
(91) The average increase of crater area per ampere of added current is about 1.85 sq. mm. This varies somewhat, but is sufficiently accurate to be used in roughly computing the light production power of different amperages. (92) The core brilliancy is fairly uniform, but somewhat lower than that of the crater floor formed upon the carbon immediately surrounding it.
The lamp itself is mechanically simple and easy to handle (93) requiring but a few things to observe in its operation.
Use the proper carbon trim, including carbons of right kind and of correct diameters, operated neither above nor below their rated amperage capacity.
Place the positive carbon in correct alignment with the optical axis of the projector optical train and in exactly central position.
Place the negative carbon in exact alignment with positive, but so located vertically that the crater burns as flat as possible and squarely facing the collector.
Have firm, clean, smooth contact between carbons and carbon contacts throughout entire length of the contact.
The arc control should maintain the arc gap steadily with as little variation in length as is possible. Many projectionists have fluctuating light production either because the arc control is in poor condition or improperly adjusted or because the arc control is badly designed and