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.
ublished i in the interest of the a Projectionist Fox (CASE Cor! ORATION
VOLUME 1, NO. 30
ESD 40:
JULY 28, 1928
Changing the Sound Lamp
HANGING the sound lamp at proper intervals is of the utmost importance. It is an insurance of a high standard of sound reproduction. That is well known, but the important question is how often should
the lamps be 2 changed? — Good and Bad Lamp Types — globe, Sorry, gentle
men, but that is a question which cannot be answered, if it be asked in that foram: There is too much dependent upon the individual lamp. Some will operate satisfactorily over a longer period than others.
About twice a week the projectionist should carefully examine each lamp, noting its condition carefully. This may be accomplished by removing the lamp holder from its support and holding it, the lamp, up to the light. If the glass is perfectly clear and clean looking, the lamp is O. K. If, however, there is the slightest indication of discoloration of the glass—a darkening of its interior surface—the lamp should be discarded and a new one installed.
Of course the projectionist will or may feel an urge to use the slightly discolored lamp just a bit longer, and thus get more service from it and reduce the “overhead” expense, but that is far from being either good practice or true economy. It is in fact very bad procedure.
As soon as the lamp globe commences to discolor
— eR ag Re he
NOTE:—Lamp “A” is in good condition, lamp “B” is badly blackened and lamp “C” has a badly sagging filament.
the amount of light entering the photo-electric cell is largely decreased. The result of this is an immediate and serious loss in the quantity of reproduced sound and its quality as well. Discoloration of the walls of the either at the top or the sides of a lamp, is proof positive that it has passed the peak of its efficiency and that it should be immediately replaced with a new lamp.
In the illustration we see a perfect lamp at “A.” There is neither discoloration of the lamp walls or sagging of the jamp filament. At “B” we see a lamp whichhas been used much too long. It is badly discolored. Undoubtedly its continued use both reduced the sound volume and injured its quality. “C” shows a lamp with two serious faults. It is discolored and instead of being straight, its filament is sagged. If a lamp filament sags at all, discard it immediately, even though there be no discoloration. You cannot secure a straight filament image if the filament itself be crooked.
It is not wise to “save” a small sum by using a sound lamp which is discolored, when you can only do so at the risk of injury to sound results. Such “economy” may be very costly in the end.
Daily careful examination of sound lamps is no great task and is an insurance against trouble and