TROWBRIDGE. — ELECTRICAL DISCHARGES. 443 



materially changed from the well known form obtained by interposing 

 a Leydeu jar in circuit with an ordinary Ruhmkorf coil. The four most 

 prominent lines are present. Further investigation will be necessary to 

 determine whether more lines are brought out by the increased electro- 

 motive force. The spectrum is exceedingly brilliant. 



In a previous paper it has been pointed out that the instantaneous de- 

 velopment of heat in disruptive discharges through hydrogen when the 

 peculiar spectrum observable in stars is obtained is very great.* This 

 spectrum is seen in the solar prominences, and therefore indicates a very 

 high temperature, apparently much higher than the surface of the sun, 

 which shows the fluted spectrum of carbon which can be produced in 

 the electric furnace. This high temperature might be due to explosions 

 of gas from the body of the sun, or it might be possibly caused by electric 

 discharges through the masses of gas thrown up by some explosive action. 

 The long continuance, however, of this spectrum of hydrogen indicates 

 a prolongation of the state of higli temperature. Electrical discharges 

 occurring oftener than sixteen times a second might produce the spec- 

 trum and still account for the apparent high continuous state of tem- 

 perature of the gas. 



Leaving, however, for the present a more careful study of the hydro- 

 gen spectrum under the conditions of extremely high electromotive force, 

 I pass on to the effects producecSsby such voltage in very highly rarefied 

 media such as are contained in Crookes tubes. In these experiments I 

 have been greatly assisted by Mr. John E. Burbank, graduate student. 



The experiments were conducted with Crookes tubes containing no 

 interval between the anode and the cathode ; and no discharge therefore, 

 in the usual sense, occurred in the tubes. A continuous conductor was 

 led through the rarefied tube, and it was discovered that the X-rays were 

 given oflf from every element of this conductor at right angles to its sur- 

 face when a disruptive discharge occurred in the circuit of which the tube 

 formed a part. This remarkable result was obtained by means of the 

 very high electromotive force obtained by the apparatus rejiresented in 

 Plate I., which was charged by ten thousand storage cells. . 



The first tube is shown in Figure 1. It consisted of a straight wire 

 tube joined to an ordinary Crookes tube of the focus pattern. This latter 

 tube was joined to the straight wire tube in order to test the vacuum in 

 the latter, and to be sure that the necessary conditions existed for the 

 production of the X-rays. When the terminals of the straight wire tube 



* Ara. Journal of Science, Vol. III., April, 1897. 



