A Wonderful X-ray Film made by M. J. Carvallo.
The process of digestion in the intestine of a frog after its removal from the body.
By courtesy of the Marey Institute.
Moving X-ray Pictures of the Digestion of a Fowl.
These pictures, taken at five per second by M. J. Carvallo, show the different phases in a complete cycle of the gizzard, which lasts exactly five seconds.
Monsieur Carvallo was probably the first worker to attempt to portray in movement the elusive and peculiar features revealed by the Röntgen rays. One or two other scientists had dabbled in the art, but their achievements were not very convincing for the simple reason that they did not employ chronophotography. Monsieur Carvallo, however, being fully aware of the valuable work that had been carried out by Dr. E. J. Marey, saw the true way of applying radiography to cinematography, and saw that it could not fail to be of scientific value. He embarked upon a number of illuminating, though tedious, experiments, in the effort to combine these two branches of photography.
Carvallo's installation was of a most elaborate character, but he accomplished some marvellous results, the full significance of which are appreciated only to-day. The complete apparatus he used in his experiments is shown in Fig. 9. The source of energy was a small electric motor, capable of making 2,000 revolutions per minute with a current of only 50 volts. This motor was extremely sensitive, since it would make 300 revolutions per minute with a current of 10 volts. The control of the speed was essential to his work, so he elaborated a simple and ingenious change-speed gear mechanism, which enabled him to drive the camera at four different speeds without touching the motor. The gear mechanism was not dissimilar from that adopted upon a larger scale in automobiles, lathes, and other machinery where the speed has to be varied according to the character of the work. The direct drive was transmitted from the motor-shaft to that of the camera mechanism through a belt and pulleys so as to secure flexibility and immunity from shocks. The three lower speeds were transmitted through gear wheels. These sets of wheels were mounted upon two parallel shafts and worked upon the sliding principle, which was found to be the simplest and most effective. In order to reduce the noise arising from the meshing and working of the gears the smaller wheels were made of fibre.