. The Bell System technical journal . 3) The entire strip was blackened (on the emulsion side) withprinters ink. (4) The emulsion on one sidt of llu- wa\e was stripped from thebase, thus leaving the profile. (5) The beginning and end were joined to form an endless belt. Piioto-Mechankal .Analysis of the Prepared Records* The i^rinciple of the |)hoto-mechanical analysis is as follows: Themotion of the strip past the image of an illuminated slit causes fluc-tuations in a beam of transmitted light which in turn, produce volt-age fluctuations in the circuit containing a selenium or photo-electricc
. The Bell System technical journal . 3) The entire strip was blackened (on the emulsion side) withprinters ink. (4) The emulsion on one sidt of llu- wa\e was stripped from thebase, thus leaving the profile. (5) The beginning and end were joined to form an endless belt. Piioto-Mechankal .Analysis of the Prepared Records* The i^rinciple of the |)hoto-mechanical analysis is as follows: Themotion of the strip past the image of an illuminated slit causes fluc-tuations in a beam of transmitted light which in turn, produce volt-age fluctuations in the circuit containing a selenium or photo-electriccell. This voltage is then anahzed by means of a tuned circuit,an amplifier and a rectifier. The frequency of any componentselected in this manner is determined by the tuning frequencydividedby the ratio of speed transformation (analysis speed divided by theoriginal speed of recording). The measured amjilitude of the selected * Pliys. Rev. 23, 1924, p. 309 It is phinned to publish a more detailud descrip-tion of this apixiratus Fig. 2—00 as in pool; spoken by M. B.—male, low pitched. Plate No. 2: made from film record No. 157-A.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
