THE CINEMATOGRAPH 



53 



a second, so that at least fifteen pictures are taken in every 

 second of time, and according to the requirements of illu- 

 mination and the rapidity of the movements of the men or 

 animals photographed this number may be greatly increased. 

 The film is developed, printed and fixed on a similar 

 rolling mechanism and the pictures are thrown one by one 

 by a powerful lantern on to a screen, and are jerked along 

 at the same rate as that at which they were taken, and are 

 magnified enormously. Animals and men in rapid move- 

 ment, railway trains, the waves of the sea are thus photo- 

 graphed, and when the serial pictures are thrown 

 successively on the screen the result is that the eye 

 detects no interval between the successive pictures — the 

 figures appear as continuous moving objects. This is 

 due to the fact that whilst the impression produced on the 

 retina of the eye by each picture lasts for a tenth of a 

 second (less with brighter light), the interval between the 

 successive pictures is only one thirtieth of a second, and 

 accordingly the retinal impression has not gone or ceased 

 before the next is there ; hence there is no break in the 

 series of retinal impressions, but continuity.* 



It is this duration of the impression on the retina which 

 prevents us from separating or "seeing distinctly" the 

 successive phases of a horse's legs as he gallops by, and 

 has led to the remarkable result that no artist has ever 

 until twenty-five years ago represented correctly any one 

 phjise of the movement of the legs in a galloping horse, 

 and it is doubtful whether that correctness is what the 

 painter of a picture really ought to put on his canvas. 

 If we examine the separate pictures of a galloping horse 

 as taken on a cinematograph film, we have before us 

 the actual record of the positions assumed by the legs 

 at intervals of the thirtieth of a second (or whatever less 

 interval and length of exposure may have been chosen), 

 * See note on page 75. 



