106. RICE’S EXPERIMENT. APPARATUS FOR OBTAINING X-RAYS. § 109, 114, 131, 137. TUBE ENERGIZED BY A WIMSHURST MACHINE. _Elect. Eng._, N.Y., Apr. 22, p. 410.—Roentgen had always employed the induction coil. As to those who first excited the discharge tube by the Holtz or Wimshurst machine or generators of like nature, it is not certain; but, according to public records, they were independently Prof. M. I. Pupin, of Columbia College, and Dr. William J. Morton, of New York. See _Electricity_, N.Y., Feb. 19, ’96. The accompanying cut marked “Rice’s Experiment, Fig. 1,” is a diagram representing the several elements of the apparatus, while “Rice’s Experiment, Fig. 2,” shows what kind of a sciagraph can be obtained by means of a Wimshurst machine. § 101, at centre. The details of the apparatus as employed by Mr. E. Wilbur Rice, Jr., Technical Director of the General Electric Co., were as follows: A Wimshurst machine, having a glass plate 16 inches diameter, coupled up with the usual small Leyden jars, spark under best conditions of atmosphere, etc., 4 inches. “The usual method of taking pictures with such a machine is to connect the interior coatings of the two jars, respectively, to the positive and negative conductors of the machine, the terminals of the discharge tube being connected between the external coatings of the Leyden jars. In this condition, the disruptive discharge of the Leyden jars passes through the tube and across the balls upon the terminals of the conductors of the machine, the length of spark being regulated by separating the balls in the usual way.” Later, he found that by omitting the Leyden jars, the generation of the X-rays was practically non-intermittent. He therefore connected the terminals of the discharge tube directly to those of the Wimshurst machine as indicated in “Rice’s Experiment, Fig. 1,” which also illustrates the details in the carrying out of the experiment for obtaining the picture, Fig. 2, of the purse containing the coins and a key. The principal feature was the introduction of a lead diaphragm containing a small central opening 7-8 inch diameter opposite the fluorescent spot. Sciagraphs taken thus required a little more time, about 60 minutes, while without the diaphragm, the time could be shortened to about 30 minutes, but the shadows were not so clear in the latter case. The figures are on p. 100. [Illustration: RICE’S EXPERIMENT. FIG. 1, § 106, p. 99. Diagram. ] [Illustration: RICE’S EXPERIMENT. FIG. 2, § 106, p. 99. Taken with the above apparatus. ] 107. SOURCE OF X-RAYS TESTED BY PROPAGATION THROUGH A SMALL HOLE.—This would illustrate not only that the fluorescent spot is the source of X-rays, but also that a very small portion comes from other parts that are probably bombarded by stray cathode rays (due to irregular surface of cathode § 57, or by reflected X-rays or cathode rays.