The international photographer (Jan-Dec 1934)

January, 1934 The INTERNATIONAL PHOTOCRAPHE Twenty-nine ORIGIN OF THE POINT, ETC. (Continued from Page 22) men failed, however, lo visualize the whole scheme. Neither recognized, so far as I am able to learn from their writings, the fundamental importance of complete spherical and hemispherical illumination, nor the fact that the molecule was the true seat of intensity. If they had grasped the full scheme I am confident that the point source theory would already have been dropped from the books. Milliken and Gale illustrate this basic truth as regards whole light sources, by including in their book, "A First Course in Physics," on page 393 of the 1906 edition, the photometer of Count Rumford which illustrates the functioning of whole flames. The authors also teach the same truth in their remarks on the standard candle. They say correctly (p. 394) : "In general, then, the candle power of any two sources which produce equal illumination on a given screen are directly proportional to the squares of the distances of the sources from the screen." (Their own italics.) Note that whole light sources are involved, while the area of the receiving screen is not referred to. This is as it should be. It is lamentable, however, that these distinguished authors offset the good effect of this correct teaching by illustrating also the erroneous point source figure on page 392. Here it is stated (after saying the usual thing, that light weakens by spreading over four times the area at distance two as at distance one) : . . . the intensity of the illumination due to a given point source must vary inversely as the square of the distance from the source." Note here that the technical point source, and not a whole source, is involved, while the area of the receiving screen is used as a factor in the problem. This statement I hold to be erroneous. It is the exact opposite of their statement first noted, which is the true one. Dull, in his "Modern Physics," also illustrates both theories. This contradiction results in the student's complete confusion as to the truth of light intensity. The fact, however, that these authors do include the truth, is hopeful, since there is left to be done only a more comprehensive elaboration of the truth and the omission of the error. In my next article I will give my own classification of the patterns of illumination which function in nature. I will show that there is one pattern in which intensity remains constant through a considerable distance from the source, and another pattern in which the intensity varies inversely to the distances instead of to the squares of the distances. I will also give my basic law of intensity which applies to these various seemingly contradictory patterns and also to full hemispheric illumination, as from the whole sky extension. Any reader who desires to keep this series of articles for reference should secure the number of August, 1932, the last, this present one and the two or three which will follow. ICTER^ In (Atarld'OOid* Us* ue^ C^Ouanli^br and (NJi^hr £ff*cts in Daytime ~F^ ScenesDiffused. Fccus.arcd many v\\i*r «Ff«crs Georcje H. Scheibo ORIGINATOR OF EFFECT FILTERS 1927 WEST 78TH ST. LOS ANGELES. CAL. 1 1 | Alvin Wyckoff h 30% to 60% CASH SAVINGS on 16 mm. and 35 mm. Cameras, Projectors and Accessories Write for Bass Bargaingram. Specify size of apparatus interested in. For over 22 years Value Leaders of the nation. Your copy is ready. Write for it. BASS CAMERA CO. 179 W. Madison St. Chicago, III. Phone CLadstone 4151 HOLLYWOOD STATE BANK The only Bank in the Industrial District of Hollywood under State Supervision Santa Monica Boulevard at Highland Avenue Howard Anderson Special Effects — Animations Culver City 3021 GRanite3111 CINEX TESTING MACHINES CINEX POLISHING MACHINES BARSAM-TOLLAR MECHANICAL WKS. 7239 Santa Monica Blvd. Phone GRanite 9707 Hollywood, California DR. G. FLOYD JACKMAN, Dentist Member Local No. 659 706 Hollywood First Nat'l Bldg., Hollywood Blvd. at Highland Hours : 9 to 5 CLadstone 7507 And by Appointment DOUBLE MATTING (3 PATENTS. 1932) mjyriLLiAMC? ▼▼SHOTS I* Phone OXford 1611 8111 Santa Monica Blvd. Hollywood, Calif. Please mention The International Photographer when corresponding with advertisers.