Januaey 31, 1896.] 



SCIENCE. 



163 



photographic plates and metal piecep in the 

 body, for example, needles, bullets, etc., 

 can be found by this method. It will be a 

 matter of the future to learn whether the 

 rays have psycho-physiological effects. 



The newspapers report that the whole 

 thing was discovered by mere chance. 

 Eontgen saw the effects on photographic 

 papers which by chance were near to a 

 covered tube during the discharge. This 

 chance origin is not probable, as Lenard, 

 the assistant of Hertz, has been working in 

 the same direction for a long time, and 

 many preparatory experiments by Rontgen 

 himself cleared slowly the way. But sup- 

 pose chance helped. There were many 

 galvanic effects in the world before Galvani 

 saw by chance the contraction of a frog's 

 leg on an iron gate. The world is always 

 full of such chances, and only the Galvanis 

 and Rontgens are few. 



Hugo Munsteebeeg, 

 Harvard University . 

 Fekibubg, Bacen, January 15, 1896. 



SCIENTIFIC NOTES AND NEWS. 



PBOFESSOE KONTGEN'S DISCOVERY. 



The transmission through wood and other 

 substances of the rays from a Crookes' vacuum 

 tube, discovered by Prof. Rontgen, is reported 

 to have been confirmed by Prof. Klupathy of 

 Pesth, Prof. Domalip of Prague, Prof. Czermak 

 of Gratz, and Mr. A. A. C. Swinton of London. 

 The photographs have been exhibited before 

 several scientific societies and by Prof. Rontgen 

 to the Emperor of Germany, from whom he has 

 received a decoration. 



Mr. Swinton writes to the Standard that 

 with Mr. J. C. M. Stanton he has obtained 

 distinct proof that the radiations in ques- 

 tion do pass easily through various substances 

 that are quite opaque to ordinary light, and do 

 produce strong impressions upon ordinary plio- 

 tographic plates entirely incased in light-proof 

 material. Indeed, all substances that he has so 

 far experimented on in his laboratory appear 

 to be transparent to these radiations, even 

 sheets of ebonite, carbon, vulcanized fibre, cop- 



per, aluminium and iron, though there is con- 

 siderable variation in degree. It is thought 

 that the new method of photography may have 

 important applications, not only in surgery, but 

 also in metallurgy, by revealing flaws, inequali- 

 ties and fractures in metals. 



Hertz discovered that cathode rays pass 

 through metal films not translucent to ordinary 

 light, and that Dr. Lenard and others have 

 published careful experiments on the subject. 

 Attention has been called to Prof. Zeugen's 

 having photographed Mt. Blanc, in 1885, by 

 the cathode rays. Prof. Rontgen, however, 

 states that the rays discovered by him, which he 

 calls X-rays, are not cathode rays, as they are 

 not refrangible nor aflPected by magnetic in- 

 fluences, but that they are more probably longi- 

 tudinal waves in the ether. 



While Hertz and Lenard hold that the cathode 

 rays are vibrations in the ether or even light of 

 short wave-length, Crookes and J. J. Thomson 

 liave urged that the rays are negatively charged 

 matter traveling with great velocity. M. Per- 

 rin reported to the Paris Academy, on December 

 30th, experiments which tend to show that the 

 latter view is correct, and some relation will 

 probably be found between cathode rays and 

 the X-rays. 



PHYSICS. 



By constructing what might be termed a 

 reversed level, A. Toepler obtains an instru- 

 ment which he calls a 'pressure level.' It 

 consists of a tube bent to a slight angle at its 

 middle point ; the two ends are equally inclined 

 to the horizontal. A short column of a light 

 liquid fills the central portion of the tube. It 

 will be readily seen that if the two open ends 

 are connected with two receivers of any sort, 

 the liquid will, by its position, give the differ- 

 ence of pressure in them. This method of dif- 

 ferentially measuring pressures, Mr. Toepler ap- 

 plies {Wied. Ann., Vol. 56, 1895) to measure the 

 difference in weight of two columns of air at 

 different temperatures but both under the same 

 pressure. A long series of determinations of ab- 

 solute temperatures bears witness to the efficacy 

 of this method, and theoretical considerations 

 remove some apparent objections and give to it 

 certain advantages over the ordinary form of 

 air thermometer. 



