Some Various Types of X-Ray Tubes.

A large number of tubes have already been employed in different experiments with, and applications of, the X-rays for photography, and in connection with the fluoroscope. Mr. G. Seguy has constructed and experimented upon several types, and he has gathered a collection which is illustrated in "La Nature."

There exist at the present time three methods of obtaining the X-rays. That employed in the very beginning is based on the direct action of the ray. The second permits of obtaining instantaneity in the radiograph, and is based on a reflection action. The third is a result of the combination of the first two methods.

In the accompanying engravings, Nos. 1, 2, 3, 4, 6, 7, 10, 11, 12, 13, 14, 17, 18, 20, 21, 24, 26, 28 and 32 are constructed according to the principles of the first methods. Nos. 5, 8, 9, 15, 16, 23, 25, 27, 29 and 30 employ the second method; that is, the theory of the reflection of the cathode rays and of the phenomenon of internal electrolysis of the volatilized molecules. The tubes Nos. 19, 22 and 31 produce X-rays according to the two combined theories.

The numbers accompanying each tube designate the design of the various experimenters, as follows: 1 and 2, Crookes ; 3, Seguy; 4, Wood; 5, Seguy; 6, Chabaud-Hurmuzescu; 7, Seguy; 8, Thompson; 9, Seguy; 10, d'Arsonval; 11, Seguy; 12, Puluj; 13, Seguy; 14, d'Arsonval; 15, Le Roux; 16, 17 and 18, Seguy; 19, de Rufz; 20, Crookes; 21, 22, 23, Seguy; 24, Roentgen; 25, Brunet-Seguy; 26, 27, Le Roux; 28, Colardeau; 29, Seguy; 30, Colardeau; 31, Seguy; 32, Roentgen.