y-une 2, i8Si] 



AT AT U RE 



113 



Prof. Trowbkidge lately observed that a steel bar magnet- 

 ised to saturation at 20" C. and subjectel to a temperature of 

 - 60° C. lost 66 per cent, of its magnetism (a much greater per- 

 centage than that formerly observed by Wiedemann). 



Prof. Robinson of Ohio concludes from experiments [your. 

 Frank!. Inst., March) that vibrations in extended media from a 

 remote single centre of disturbance, can only be longitudinal, 

 even in light ; that vibrations will be to some extent transversal 

 when due to two or more centres of di>turbance not in the same 

 line ; and that undulations, to be in a condition called polarised, 

 must consist of vibrations which are transversal, and that no 

 necessity exists for assuming vibrations transversal in front of a 

 polariser. These views are not only contrary to the accepted 

 wave-theory of light, and to the conclusions derived from Max- 

 well's electromagnetic theory, but appear to be directly negatived 

 by the experiments of Stokes and Figeau. 



In his third pai^er on electrical shadows {Go/t. Soc. Nachr., 

 February 5) Herr Holtz studies, inter alia, the differences in 

 form of the light surface and shadows from the two electricities ; 

 the effects of using differently-conducting surfaces u der the sill<, 

 and of using convex and concave spherical or cylindrical sur- 

 faces ; the double shadows from two surfaces used as electrodes ; 

 the use of a silk screen between pointed electrodes, &c. 



A NEW seismometer is described by Dr. G. Wagener of Kioto, 

 Japan, for which he claims several advantages over the ordinary 

 heavy-pendulum seismometers. It consists of a strong rigid 

 fi:ame in the form of a short quadrangular pyramid, from which 

 is suspended an iron ball weighing about fifty pounds by means 

 of a bundle of untwisted silk fibres three feet long. Below this 

 ball is an indicating pendulum consisting of a hollow sphere 

 pivoted near its centre of suspension upon a small polished ball, 

 also rigidly fixed to the frame, and carrying beneath it a light 

 arm, whereby its motions are multiplied twenty-four times. A 

 small sphere fixed to the bottom of the iron ball plays into a 

 cavity in the summit of the indicating pendulum. The latter 

 has, by reason of its construction, a very short period of oscilla- 

 tion as compared with that of the iron ball. Hence when an 

 earthquake occurs the inertia of the heavy ball will keep it for 

 a considerable time in its position, while the pointer of the indi- 

 cating pendulum moves towaid the region whence the disturb- 

 ance came, and can return almost in-tantly if the horizontal 

 displacement be succeeded by a displacement in the opposite 

 direction. That the movement of the pendulum may be regis- 

 tered accurately in point of time, a small silk thread attached to 

 the bottom of the indicating pendulum passes through a small 

 eye-hole in a porcelain plate immediately beneath, and thence 

 passes round a light indicating wheel » hich is also in connection 

 vidth a lever which at the slightest movement drops, and stops a 

 clock. A kindred apparatus is employed to register the direc- 

 tion of the shock, eight threads from the indicating pendulum 

 of a similar instrument being wound round ei^ht indicating 

 wheels for the eight chief points of the compass. For these 

 instruments it is claimed that there is less error from oscillations 

 than in the usual instruments, the inertia of the indicating pendu- 

 lum checking the tendency of the weight to swing. A further 

 registering apparatus, consisting of a chronograph drum actuated 

 by a clock which is started by the first shock, is also described. 

 It does not appear that the registering apparatus of Dr. Wagener 

 is in any way an improvement upon the electrical apparatus 

 hitherto employed. Lastly, Dr. Wagener describes an instru- 

 ment for measuring any possible vertical displacements, a heavy 

 body of considerable inertia being counterpoised while immersed 

 in a tub of water, its movements being magnified by a lever and 

 registered by a thread-wheel arrangement. 



M. Gaiffe gives us reason to suppose that part of the dis- 

 turbance in telephone lines, usually set down to "induction," 

 is due to the conducting-wires being of a magnetisable metal 

 iron, which, when moved in the magnetic field of the earth, 

 experience induction-currents. M. Gaiffe introduced into a 

 telephone-circuit two pieces of steel wire, one magnetised, the 

 other not. On hittiig them so as to make them vibrate sharply, 

 sounds were produced in the telephone more strongly by the 

 magnetised strip. The remedy is obviously to employ condocting- 

 wires of some non-magnetic substance, such as copper or 

 manganese bronze. 



According to P. Tacchini, there are in the sun two regions 

 of spots and faculae at about equal distance (20° and 22°) from 

 the equator, and about the same longitude, which showed con- 



tinual activity last year. The fact he considers important for 

 theories as to the sun's physical constitution. 



The last number of the yoiirna/ of the Chemical and Physi- 

 cal Society of St. Petersburg (vol. xiii., fascicule 4) c mtains 

 two letters by Prof. A. M. Boutleroff on ice under critical pres- 

 sure. The former of them was written on February 13, when 

 Prof. Boutleroff had not yet received the number of Nature 

 which contains a detailed description of Prof. Carnelley's ex- 

 periments ; the second on March 17. The experiments which 

 he has made, and which he describes in this second letter, were 

 made. Prof Boutleroff says, on the same conditions as those of 

 Prof. Carnelley, but the temperature of ice remained at -6" ; a 

 rise of temperature was observed only when a part of the bulb 

 of the therjnometer was free from ice, but even in this case it 

 was very slow. " The refrigerating influence of ice was quite 

 manifest, but it was not at any time possible to discover anything 

 showing a rise of temperature." Prof. Boutleroff supposes that 

 Prof. Carnelley has raised tlie temperature of his thermometer 

 without raising that of ice. "It is true," he says, "that the 

 calorimetric experiment of Prof. Carnelley seems to speak in 

 favour of a heating of the ice itself ; but can we not suppose 

 that a kind of covering of hot vapour which was around the ice, 

 remaining on its surface, was transported into the water of the 

 calorimeter, and there neutralised the refrigerating power of the 

 ice ?" Prof. Boutleroff proposes also, for the same experiments, 

 to make u-^e of a cryopfiorus which might be easily appropriated 

 for that U'e, and which he describes in that case as a cryoscope. 

 When repeating Prof Carnelley's experiments with a cryoscope, 

 Prof. Boutleroff hapjiened to raise the temperature of the ther- 

 mometer to +40", whilst the bull) of tlie thermometer was nearly 

 completely covered with ice ; but he failed to raise the tempera- 

 ture when he covered the surface of the bulb with a small sheet 

 of platina. He concludes that the bulb of the thermometer in 

 those cases, w hen it shows a temperature above zero, enters into 

 contact w ith ice only at some few sjwts ; and the rise of the 

 thermometer might be explained, not only by the thermal trans- 

 lucency of the ice, but also by the circumstance that the vapour 

 disengaged by the melting ice is lieatcd, and reaches the liulb of 

 the thermometer by the small channels formed in the ice; he 

 therefore concludes that I'rof. Carnelley's condition as to the ice 

 being in a special state not quite reliable. 



GEOGRAPHICAL NOTES 



Dr. Wild, president of the International Polar Commission, 

 has issued a circular stating that six countries have already inti- 

 mated their intention to co-operate in carrying out the scheme of 

 smmltaneous meteorological, magnetical, and other physical 

 observations in the Arctic regions. These countries, with the 

 proposed station*, are Denmark at Upernivik, Norway in Fin- 

 mark, Austria-Hungary in Jan Mayen, or perhaps East Green- 

 land, Russia in Novaya Zemlya and at the mouth.of the Lena, 

 Sweden in Spitzbergen, and the United States at Point 

 Barrow and in Lady Franklin Bay. Sliould other countries 

 send in their adhesion to the scheme, this disposition of the 

 stations may be somewhat modified. We are glad to see there is 

 a probability that Germany may establish a station in the Island 

 of South Georgia, and France a station at Cape Horn. An 

 interesting feature in the scheme is that two of the eight proposed 

 Arctic stations are to be equipped at the expense of priva'.e indi- 

 viduals, viz., the station in Jan Mayen or in East Greenland 

 at the expense of Count H. von Wilczek of Vienna, and the 

 station in Spitzbergen, as our readers are already aware, by M. 

 L. O. Smith of Stockholm. Is it possible that no public-spirited 

 Englishman will be found to provide the means for England co- 

 operating in this truly international scheme of physical observa- 

 tions in the Polar regions, which play such an important role in 

 the meteorology of the globe ? 



As much has been heard of late respecting the magnificent 

 harbour which the French are likely to make of Lake Bize ta in 

 Tunis, it may be well to correct a misapprehension which has 

 long existed as to its depth. Even in the most recent gazetteers 

 this is said to be fifty fathoms, w hereas in a brief but excellent 

 paper w hich he sent to the Geographical Society many years 

 ago, Admiral Spratt, speaking from his own soundings on the 

 spot, explicitly states that the greatest depth of water in tlie lake 

 is eight fathoms, with an average of from five to six fathoms. This 

 would noc'oubt be sufBcient for all practical purposes, but at the 



