68 1 



Pin- :OGRESS OF, IN 1805. 



nUclr by an electrical an-1 photographic met hod 



rve m.th.HU which have hitherto 



been osed. The K ' nbid.. 



Aocost) find th 



fdoBf two parallerwires t. x 10' 



otnfliiurf res per second a value that differ 

 the relorilv of light by less than 2 per cent., and 

 frosa the ratio between the 2 systems of electro- 

 . , QftrbMfp md 



. - Vnnalen," Xovcin- 

 have made a prism capab! 



resonators made of tinfoil on a so- 

 rfeofmnJld glass plate*. Tin; ra 



id Wangle* differing with the wave 1, -ngth. 

 They conclude from their experiment- t hat t he 

 rays of electric force are not necessarily to be 

 regarded physically n monochromatic. but as 



Compound ' . h j unification as ordinary 



light, llelmholt/'s theory of color disj 



-.* fresh support from their experiments. 



Philosophical Magazine," April) h 

 vesttaUed the passage of a wave train from an 

 oscillator through a conducting dielectric, and 



:, ; t the i of the reflected ravs, 



the phase changes, etc.. for damped wave trains 

 reflected from such a plate differ very coi. 



n some cases from those for st.- .1 ly rays, 

 BJafknsj (Wiedemann's "Annalen," January) 

 concludes t ha 1 in the phenomena called "multi- 

 ple resonance n there are not as many stationary 

 wave systems as there are nodal systems exhib- 

 ited by the resonator, but that these periods 

 are due to the resonator, which resounds to a 

 Mtnple . ^-illation at different points. The differ- 

 ence between electric waves and light waves he 

 regard* as lying in the fact that the former are 

 damped, while the latter are maintained. 

 (Wiedemann's M Annalen") has demonstrated 

 that electric waves are doubly refracted in 

 wood, the Telocity of propagation being differ- 

 ent across and along the fibers. His experiment 

 was analogous to the common optical experi- 

 ment of restoring the light intercepted by 2 

 Kksol prisms with their principal planes at right 

 angles by inserting a doubly refractory sub- 

 Unce.asatourmaline.lH-t ween th.-m. The Nic..l 

 prisms were represented by iiert/ian concave 

 mirrors with crossed focal lines and the tourma- 

 line b? a plate of wood in inches thick. Iljcrk- 

 nes (Wiedemann's M Annalen." May) has d< 

 rrcral new laws of electric resonance. I le finds 

 that the secondary spark potential is pn.por- 

 Uooal tothesqoareof tli- jM-riod of the resona- 

 tor, the magnetic or thermal integral effect to 

 its ml*, and the electric integral effect to its 

 fifth power. Aurhkinawi (Merlin Physical So- 

 v. .10. 1894) finds that tinfo, 

 'arall r show dimini- 



that i- i|uitp independent of the a- 

 of tfce light of the primary sparks. It p 

 lUr tfcc cessation of the '-..-illations but re- 



i it* original value on percu^ 



JatnaV Gotten ki": 



I in - Nature,** Nov. 21) has exporin. 

 M ta* tinfoil grating a* n e X pos- 



o ndietion c ,f ahot 60 centimetres' wave 



|U crmtina whose resistances were re- 



paeUvelT 130 am) 2K ohms, the resistance fell in 



caw* a* much an 11 and 42 ohms respec- 



; bat it w*t nearly restoml to its former 



value by gentle tapping. The aiiirle n:;. 

 the plane of |iolan/ati.-n of the radiatii-: 

 the strips of the grating influen--. -, th, 

 ance. \\liieh ; \\hen tli 



pendieular to the plane of the priniavv "-( illa- 



The author concludes that 1 1 

 a mechanical one. and thinks that it max - 

 t.. small points on nei^li!orr 

 l.\ iln- . 



.1. |\*|i : .-.i.-iiiann's " Annah-n." 1 ' 



\plains t he .strong dampii 

 .. nietals iijion 



I heir circular or t ra ns\ .)-. mau'iift i/at ion. 

 crowils the oscillations into id,- sin 

 nii'i-e than with other mrtaN. ||,. M , , t),, 

 le wire t<> rlc. -trie . 



t ions is much greater thun that of antli' 

 of cipial cornliic-lixity. hrude (\\ied.i 

 " Ann. ' uar\ i has in\ .-: i-at rd i|.. 



lion lct\\.-.-n a s M l. stance's dielectric c 



and the period of the elect 1 



it. which he calls the "electric djspn 

 alcohol, this quantity is normal and of tl,' 

 order of magnitude as the optical disp. 

 I'liormal dispersion, and > 

 none at all that was percept il.l.-. nun, 

 sterdam Royal Academy. Sept. v 

 result "f experiments "on elc. 

 wat.-r (1) that there is no di-p.-rsion 

 the frequency of 27,00* MM MI t.. 1)7,000,000 a sec- 

 ond, and rJi that the refractive index for 

 of which then- are several hundred mil!. 

 second equals the Mpiaiv root of the S] 

 inductive capacity measured statically. 

 /'//--- [7'y. Klster and C.-itel ; 



niv) have constructed a jihoto-elcct i ; 

 consisting of an exhausted ^]n-- ^lolie with nn 

 anode (f platinum win- and a cathode of -odiutn- 

 potassium allov. When t he cell was illun. 

 liy li^ht from incandc-ci-nt xircon. polari/ 

 passage through a Nicnl prism, the current tha't 

 passed through it when its terminals wen 

 necied to a 400-volt linttery was found to d 

 in strength upon tho angle of incidence of the 

 light and on it- plane ,,f polari/at ion. 



-i when the plane of polari/at ion was 

 perpendicular to the plane of incidence and when 

 the angle of incidence was about 00 



:ii:le of the alloy. llranl;. 



. in studying the rate of lo^ 

 charge from the effect of light in the . 

 l.adly conducting liodies. finds that when the 

 light is from a liody heated to a <lull red the 

 condition of the illuminating surface pl;r 

 chief part in the phenomena, the nature of the 

 charged Ixidy having no effect. But if the light 

 is rich in the hiirhly refrangible rays, tho eflSJC 



i- on the illuminated body, but in : 

 all cases this loses elect rieity. With 

 marble, canlboard. terra cotta. MM! hot L 

 i- lost M ,ore rapidly than 



:ie. while the oppo>it- ; 

 wood or metal varnished or coated wr 

 paraffin, or tallow. 



Cat! 

 Scjcne,-. .Fan. 14) finds that the product 



SO-called catho'i ' depend - 



discharge from metallic e]. 



.s; that they are produced chiefly where 

 the primary illumination attains a con si d< 

 intensity; and that their direction of pr 



