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.
This applies to all the cases of condensing and reflecting systems that we have tried out.
Mr. \' ictor : It seems to me that the tests we have been interested in — at least I express my personal interest — is in the advantage of difl:'erent condensing lens systems as used in motion picture machines for the purpose of projection. In other words, it is a matter of obtaining the most brilliantly illuminated screen image, and to me, with all due respect to Dr. Story's very painstaking data, I am not convinced we have this test until we get a screen test. Now, you may be able to put, by focusing on the aperture or elsewhere, a tremendous amount of illumination, but it is only that portion of illumination that gives us a clear, sharp well-defined image on the screen that we can use. The rest is a by-product which is like the squeals of the pigs in Chicago — we don't know what to do with it. (Laughter.) And I am still waiting for accurate information as to the relative merits between large condensers, prismatic condensers, and the small condensers of which I am personally an advocate.
Mr. Egeler : Dr. Story has called attention to the fact that the application of these fundamental data involves consideration of the extent to which the uniform source employed can be duplicated in a practical incandescent lamp ; among the principal factors are the relation of the source size (wattage) to the bulb diameter, the ratio between the average brilliancy of the soruce area to the maximum corresponding to a given lamp life, and the effect of the nonuniformity of the source brilliancy on the screen illumination. The minimum spacing between the source and the condenser is dependent on the bulb size, which in turn is a function of the lamp wattage. For a monoplane filament the wattage of a square source increases approximately as the square of the side dimension. The size of the source and the screen illumination are therefore limited for the small condensers by the w^attage which can be placed in a bulb which will allow the filament to be placed the desired distance from the condenser. This limitation, together with the lower permissible operating temperature for the small low-current sources, counteracts in part the advantages obtained with the theoretical source.
In applyping data such as have been presented, it has been found that the non-uniformity of the screen illumination resulting from the non-luminous areas between the lamp filament coils will require that source-condenser and condenser-aperture spacings be modified in order that the screen will be illuminated to a satisfactory degree of evenness. A choice is accordingly based on a compromise between the amount of light projected and the uniformity of the screen illumination. This is because increase in the size of the beam at the aperture is to be expected when the spacings are changed from the values for maximum light, and the amount of light reaching the projection lens as a result is decreased. The loss of light at the aperture is materially less for the small condensers with which the aperture can be placed close to the condensing lens.
Data obtained with lamps of limiting wattages for bulbs wdiich can be used with the large and small condensers show that a much
S3