The Moving Picture World (July 1907)

THE MOVING PICTURE WORLD. 281 av anything against the great slide houses of the coun- They all have excellent lists of slides from which Jselect, but one is never able to properly illustrate a rture which was prepared before the slides were ^ct e d With the usual perversity of things inanimate tis practically impossible to get one hundred, or even 1 .Jtrfrrr. slides which will satisfactorily illustrate a ecture prepared in the study. The only possible way to to it is to decide upon a subject, then look for slides vhich will illustrate that subject and afterward write he lecture around the illustrations. It is a poor way, ,ut when an attempt is made to do a thing one way and t fails the only way left is to do what is possible, and hat is, write a story around the pictures. Many lecturers do this-with a certain degree of suc- ess. I have in mind now one who is popular on the educational force of a large city, but there is always an dement of dissatisfaction after hearing one of his lectures. [Tie text and the pictures do not seem to connect imoothly. One who has never been in the business will ay that it is because of lack of comprehension of the subject, but the experienced lecturer will understand mmediately that the slides were prepared by a profess- ional for his stock and the lecturer has utilized them is well as possible in illustrating his talk. This chance of missing the object aimed at need not Jeter one from adopting the same course. Under many ircumstances it is impossible to do otherwise and numer- )us valuable messages have been given to the world in his way, and many audiences have been charmed and nstructed with lectures prepared and illustrated in this nanner. Still,'the fact remains that occasionally a lec- urer aims at something more than a mere money suc- ess. He desires to have his lectures impressive and ufficiently good to be remembered for their general xcellence rather than for some other reason. It requires long, hard work to outline, prepare and ustrate a lecture, no matter what the subject may be. urther, a lecture is never really complete. It may be, nd probably is, complete enough to be delivered, but ifter one begins delivering it the lecture apparently be- ames a living thing. It is undergoing constant changes. t is being revised continuously. New pictures are being dded and old ones. are being withdrawn. New facts e being inserted and old statements are being modified meet changed conditions. The set lecture, which is irmted and read .from the page, is cold and in many rays unsatisfactory. It requires something alive, some- hing which has the human element, something developed ind which will touch the hearts, or the minds, of the isteners who are human, as well as the lecturer, and dio will thrill responsively to the human feeling with hich the lecture may be imbued. Where the lecturer prepares his lecture by going over ne ground himself, obtaining and arranging his own aterial and making his own pictures, then there will be armony between all the parts and the lecture will pos- ess that indefinable something which is easily and quickly ecognized, but can scarcely be described, but which ^ans its success. It requires months, perhaps years, 'hard work to do this; but once it is done and the lee- 'eis placed before the intelligent audiences which at- end illustrated lectures the returns for the labor ex- *oded begin and afterward the lecturer is well rewarded or his properly directed efforts. it is the purpose of the writer to outline more or less ftphically and minutely the different processes to be allowed in selecting a subject, preparing the lecture itself n d the illustrating. They are all important elements in one's success and a somewhat careful treatment is de- sirable. And yet it is difficult to lay down rules for such work. It is easy enough for one man to tell an- other how he performed certain work or managed a certain coup which yielded him rich returns in one way or another; but after listening to the explanation it will be found impossible for the second man to repeat the experiment with anything approaching the success of the first. It is somewhat so in lecturing. It is easy for one man to tell another how he does it, or has done it, in times past; but he cannot gurantee that following the directions he lays down will yield equally satisfactory results. But the statement of certain principles upon which to base one's work may result in the development of ideas which will lead naturally to modifications that will make the work of the second man quite as effective and valu- able as that of the first, only in a different way. With that object in view this series is begun and it is hoped that much good may be accomplished. MOVING PICTURE MAKING AN ART.—The art of recording photographically successive phases of motion or the changes in an animated scene is called chronopho- tography. This was made possible when the photographic plates reached the stage of sensitiveness which permitted of exposure so brief that during the interval of exposure the body which is being photographed shall not percep- tibly have changed its position. In the case of comparative slow motion it is possible to construct shutters, the action of which is prompt enough to fulfill this condition. In other cases, however, such as the photographing the flight of a bullet from the muzzle of a gun, the ex- ceeding brevity of exposure is obtained by the use of the electric spark, the duration of which can be reduced at will almost indefinitely. ^ The earliest example of chronophotogcaphy is due to Gedderson, who in 1862 flashed the image of an electric spark across the image of a sensitized plate by means of a lens and a revolving mirror, and in this way he suc- ceeded in securing photographs. The achievement was considered remarkable consider- ing the undeveloped state of the photographic art at that time and the fact that it was necessary to use the old- fashioned wet plates. For many purposes, particularly in scientific work., chronophotography may be most easily reached by throw- ing the image of the moving body upon a plate which travels more or less rapidly through the field of view of the camera. The photographic image of a point at rest obtained in this way is a line drawn across the plate in the direction of its motion. All displacements of the points at right angles to the line Of motion of the plate produce corresponding transverse displacement of the line that forms its image. The scientific applications of this form of chronopho- tography are of two kinds—(a) the automatic registry of changes which occur so slowly that the direct obser- vation of them becomes laborious. The continuous daily records of the fluctuation of thermometers and barom- eters are of this description. In such cases the shadow of the moving point is thrown upon a strip of photo- graphic paper of small sensitiveness which is moving very slowly, (b) The tracing of fluctuations too rapid to permit of direct observation with the eye. In such cases the plate or film is moved at a high velocity through the field of the camera, and motions, the duration of which