I 6 8 Notes and Comments. [J. F. I.,

I M P R O V E D ELECTRIC INCANDESCENT L I G H T .

Nernst , a wel l .known German electrician, has pa t en t ed an i m p r o v e m e n in electrical glow l ights which consists in the use of a cyl inder of magnesia, or s imilar substance, which possesses the proper ty of be ing a non-conductor t of electricity when cold, aud of becoming conduct ive when hea ted to a h igh temperature. These cyl inders are provided wi th electr ical connect ions , and means - - such as a Bunsen bu r ne r - - a r e used to hea t t h e m to the conductive temperature , when the cur ren t alone will ma in ta in t hem in incandescence.

W.

N E W USES FOR GLASS.

Exper iments have lately been made wi th glass as a subst i tu te for metals for bearings. The .mos t suitable k inds were found to be bot t le and ordinary Window glass. The bear ings were cast in moulds, in two pieces. ' They gave the best results when m oun t ed in elastic supports. I t was found to be neces- sary t ha t the revolving par ts should be well ba lanced and the shafts accurately centered. The results are stated to have been t ha t the glass bear ings require less lubricat ion, have less friction, and in many cases are more advantageous t h a n meta l bearings, t hough in some cases they afford less securi ty than others.

I t is recorded in the F r e n c h journal , L'Eclairage Electrique, t ha t a t Mar- seilles, glass tubes are be ing used as underg round conduits for t e legraph wires and for carrying electr ic- l ight wires in factories, theatres, etc. W.

ASPHALT JOINTS FO R GLAZED S T O N E W A R E (TERRA-COTTA) PIPES.

In Germany, i t is said, asphal t jo in ts for terra-cotta pipes are now used in all the chief cities. The mel ted asphal t is poured around the socket end of the pipes when the two ends had been b rough t together . On tes t ing such joints by hydraul ic pressure, the pipes were found to give way before the joints showed any signs of leaking. W.

N I C K E L - S T E E L F O R M A R I N E B O I L E R S AND E N G I N E S .

The latest applicat ions of nickel-steel are in connect ion wi th marine boilers and engines. This alloy is found to be much superior to o ther kinds of steel for mar ine boiler plates on account of its greater resistance to the corrosive action of salt water. I t is also found to be excel lent ly adapted on account of its great toughness for parts of mar ine engines, especially for the hollow shafts used on the latest t ransat lant ic steamers. W.

COSMIC DUST IN HAIL.

Professor Karpinsky, a wel l -known Russian savant, recent ly made an inter- es t ing communicat ion to the St. Pe tersburg Academy on a fall of ha i l observed on April 3 o, 1897, by M. Czeruik, near Ivangorod, in Russian Poland.

The fol lowing account of the occurrence is t aken from London Nature :

Feb., I899.] Notes and Comments 16 9

The hail was falling that day from two nearly opposite directions, and was of two entirely different kinds. One variety consisted of large grains of pear shape, and of a peculiar structure; while the other consisted of smaller, trans- parent grains, which had the shape of flattened ellipsoids. These latter con- tained nothing, but the former had in their central opaque portions black granules, which proved, on chemical analysis, to consist of iron, with traces of nickel and cobalt, and silicon. These granules were sent to the Academy, and Professor Kaxpinsky analyzed them. The powder obtained from these granules consisted chiefly of magnetic iron oxide, which had been formed through the oxidation of metallic iron; the latter could be seen very well. Moreover, the granules contained augite and, probably, sulphuretted iron, and some other substances not yet determined. Besides iron, they also showed traces of nickel and sulphur. " Such a composition," the RtL~sian professor concludes, " l eaves not the slightest doubt about the cosmic origin of the granules contained in that ha i l . " I t is interesting to note that, some t ime ago, M. Czernik collected at the same spot hail which contained granules of volcanic ashes from Vesuvius. W.

EXTRI~MELY ANCIENT MIRRORS.

At one of the recent sessions of the French Academy, Berthelot described three metal-backed glass mirrors of great antiquity which had been origi- nally discovered in Thrace and Egypt. The metal backing of these mirrors consists of almost pure lead, which, in the molten state, appears to have been poured on the concave surface of disks cut from balloons of blown glass. This appears to be a highly important contribution to the history of the arts among the ancients. W.

IGNITING C O M P O S I T I O N - F O R A S E L F - L I G H T I N G GAS-BURNER.

A recent German patent describes in the following terms the preparation of a gas-igniting composition for the automatic lighting of gas-burners. Very p0rou~ carbon (charcoal or coke?) is submitted at a high temperature to the action of chlorine vapors, then "thoroughly purified by washing. The mass is now saturated with a solution of palladium chloride, and heated in a cur- rent of hydrogen gas, whereby the palladium is reduced to the metallic state, and disseminated in the pores of the carbon in a state of extremely fine division. W.

A NOVEL PROPOSITION FOR R E A C H I N G T H E NORTH POLE.

Admiral Makaroff, the well-known Russian explorer of the North Pacific Ocean, has lately made the interesting and novel suggestion to reach the North Pole by means of powerful ice-breaking vessels. London Nature gives the following account of his proposition :

"The proposal sounds rather strange at first, but the Russian Admiral bases it on sound scientific reasoning and on a good deal of actual experience. Ice-breakers have been used in Russia (at Cronstadt) since 1864, and lately great progress was achieved in their construction in America by arming such