76 Scientific Intelligence. 



of this line and finds its wave-length to be 5571 =h 0*5. Vogel 

 gives for the same line 5571*3 ± 0*92. Gyllenskiuld gives a 

 value 55 70-0 ± 0*88. Krafft however found 5595 and 5586. Hug- 

 gins points out that Lockyer's recent statement " that the char- 

 acteristic line of the aurora is the remnant of the brightest 

 manganese fluting at 558," is clearly inadmissible considering 

 the evidence we have of the position of this line. — Nature, May 

 16, 1889. j. t. 



6. Quartz as an insulator. — At a Royal Society Conversazione, 

 Mr. C. V. Boys exhibited an " experiment showing the insula- 

 tion power of quartz. A pair of gold leaves are supported by a 

 short rod of quartz which has been melted and drawn out about 

 three quarters of an inch. The atmosphere is kept moist by a 

 dish of water. Under these circumstances a glass insulating stem 

 allows all the charge to escape in a second or two. With the 

 quartz but little change is observed in four or five hours. The 

 quartz may be dipped in water and put back in its place with the 

 water upon it. It insulates apparently as well as before." — Na- 

 ture, May 16, 1889. j. t. 



7. Light and Magnetism. — Mr. Shelford Bidwell has made 

 the following experiment. One end of an iron bar which had 

 been magnetized and demagnetized, was placed near a magnet- 

 ometer needle. On directing a beam of light on the bar an 

 immediate deflection of the needle resulted, and on cutting off 

 the light the needle promptly returned to near its initial position. 

 The direction of magnetization induced by the light is the same 

 as the previous magnetization, and the bar seems to be in an un- 

 stable magnetic state. That the effect is due to light and not to 

 heat, the author thinks, is rendered probable by the suddenness of 

 the action. — Physical Soc, London. — Nature, May 16, 1889. 



J. T. 



8. Telephonic vibrations. — Dr. Frohlich attaches a small 

 mirror to the iron plate of a telephone and from this the light of 

 an electric lamp is reflected to a polygonal rotating mirror, from 

 which it falls on a screen. The vibrations of the plate were thus 

 made visible on the screen, and since each side of the polygonal 

 mirror cast its own image, when the mirror was rotated the 

 curves were seen moving over the screen. The more rapidly the 

 mirror was rotated the slower did the curves move over the 

 screen, and when the rotation was as rapid as the vibration of the 

 plate, the curves became stationary and could thus be exactly 

 observed and drawn. These luminous curves could also be 

 photographed. The speaker had employed this method in a 

 series of researches on certain electrical phenomena which might 

 influence the efficiency of the telephone. Thus the action of 

 alternating currents, of self induction, of the rise and fall of the 

 current on making and breaking, of the introduction of electro- 

 magnets, and of other conditions, were studied by means of the 

 altered mode of vibration of the telephone plate. The speaker 

 had further obtained a graphic record of the vibration of the 



