17 



1896.] -•- ♦ 



Remarks made at the Demonstration of the Rontgen Ray, 

 at Stated Meeting, February 21, 1896. 



Prof. Goodspeed describes his apparatus as follows : 



In order to economize time it may be worth wliile for me to call your 

 attention very briefly to the apparatus that we will use to-night, before 

 beginning the reading of the regular paper. We have here two 

 terminal wires which are supplied with the electric current from several 

 storage batteries which are behind a screen. The electro-motive force 

 IS about sixteen volts. This induction coil which is to furnish the cur- 

 rent to stimulate the tube has a primary resistance of about three-tenths 

 ohm. The resistance of the secondary coil is about 3300 ohms, dead 

 resistance. By passing the primary current through the small resist- 

 ance coil and interrupting it frequently, as you all know, we produce 

 an induced current in the high resistance secondary coil. It is the dis- 

 charge of this induced current through the Crookes tube which you see 

 here that produces the green phosphorescence and secondarily, prob- 

 ably, produces or sets up the form of energy with which we are to deal 

 this evening. 



In order to make a test case I will place this little pocketbook, with 

 a couple of coins and an iron key inside it, upon a sensitive photo- 

 graphic plate, which is placed upon the table wrapped in several thick- 

 nesses of light-tight paper. The plate, as you will see, is three or four 

 inches below the lower end of the tube. The tube is much larger than 

 is usually seen ; and for that reason, probably, is more efficient. The 

 internal pressure is probably about one one-millionth of an atmosphere. 

 The exposure may continue during the reading of the paper. Subse- 

 quently we will have the plate developed. 



The Roxtgex Phenomena. 



Gentlemen : — Never before in the history of science has a new discovery 

 commanded such intense and universal interest as that, some of the 

 features of which we have met here to-night to witness. Less than 

 two months ago, the civilized world was startled at the unofficial an- 

 nouncement that Prof. Eoutgen, of Wiirzburg, had discovered a form 

 of energy probably related to radiation, which would pass through 

 many substances that were opaque to known forms of ether energy. 

 An interesting point in this connection was that glass, ordinarily so 

 transparent to light, seemed to be quite opaque to the new energy. 

 Since the original paper of Rontgen has appeared, we have learned that 

 the discovery referred to resulted from a series of experiments on fluo- 

 rescence. The important pieces of apparatus that were used, and which 

 we have before us this evening, consist of an inductorium with its 

 secondary coil connected to a well-exhausted Crookes tube. A high 

 degree of exhaustion is noted by the absence of a bluish halo about one 



PROC. AMEK. PHILOS. SOC. XXXV. 150. C. PRINTED MAY 25. 1896. 



