June 21, 1894J 



NA TURE 



179 



altribuled to T. Mayer, whose invesligations were published 

 after his death, by Lichtenberg, in 1775, although the principal 

 merit for their employment in meteorology is undoubtedly due 

 to Bessel, who explained their use in a treatise published in 

 1S14. The last two sections deal with the means of deducing 

 the harmonic constants from the usual formula;, and the need of 

 further ini'estigations by this method. The Proqraiinn will pro- 

 bably not be generally accessible, but a careful summary of it, 

 by Dr. Grossmann, will be founii in the Meteorologische Zeit- 

 schrifl for May of this year. 



The results of meteorological observations lose much of their 

 interest when published four years late. Such is the report of 

 the meteorological service of the Dominion of Canada for 18S9, 

 a copy of which has just reache 1 us. We note in glancing 

 through the volume that meteoroIot;ical instruments are supplied 

 10 the experimenlal farms established in different provinces of the 

 Dominion. There were 1126 warnings of approaching storms 

 made during the year, 82 2 per cent, of which were verified. 

 The railway companies in Canada give assistance in many ways 

 to the meteorological service. One of these is by permitting 

 trains to carry discs showing the weather forecasls for the dis- 

 tricts through which thty travel. A few weeks ago we noted 

 that our Hoard of Agriculture intended to distribute in rural 

 districts during harvest time, weather forecasts prepared at the 

 Meteotological OlTice. It may be worth consideration whether 

 >uch a system could not be usefully extended by displaying the 

 predictions on trains running through agricultural districts. 



The earthquake in Baluchistan, described in Nature of 

 August 10, 1893, was also felt in South Russia and in 

 Germany, and a comparison of the records at Nikolaiev and 

 Strassburg is given by Ilerr E. von Rebeur-Paschwitz in the 

 Ai'.rcnomische A'atliriclitc'i, No. 3234. The epicentre of the 

 earthquake was a spot fifty miles to the N.N.W. of (Juetta. 

 The main shock occurred at I2h- 19m. G. M.T. on December 

 19, 1S92. The distances from Strassburg and Nikolaiev are 5290 

 and 3480 km. respectively. The first waves from the dis- 

 turbance reached Strassburg in 16 min. with a velocity of 

 5 5 1 km. per .second, this being about the same velocity as that 

 observed in the case of the Wjernoje eanhquake of July 11, 

 18S9. The first Uiaxima took iSmins. and 30 mins. respectively 

 to traverse the disiances. It is very evident that the wave motion 

 at some distance from the epicentre is very complicated. For 

 several hours before and after the earthquake earth tremors, 

 were recorded by the instrument--, the two kinds of disturbances 

 appearing to proceed independently of each other. 



SoMK interesting experiments with a rectangular glass prism 

 are described by W. C. Ronlgen in iriidcmaiiii's AniiaUit. 

 Those who have tried looking at themselves as reflected by two 

 mirror?, placed at right angles to each other, will remember 

 the amusing effect created by the image, contrary to the usual 

 reflection in a mirror, not being reversed right and left. \Vc 

 can see ourselves "as others see us," als", by looking stoight 

 at the surface subtending the right angle of a reclangular prism. 

 Herr Runtgen observes that in no case is the pupil divided 

 into two equal parts by the faintly visible edge of the prism. 

 This is an illustration of the angle between the line of vision 

 and the axis of the eye, which is different in different peop'e. 

 Rectangular prisms can be easily tested for cotrectness of the 

 angle by observing whether the two images of the cross-wires in 

 a telescope, as seen in the two surfaces, coincide. The same 

 lest would tell us whether two mirrors are exactly at right 

 angles — a fact which might be usefully applied for testing 

 instruments like Gauss s heliotrope. Such a pair of mirrors, 

 or a rectangular glass prism, give rise to another peculiar 

 phenomenon. If they are rotated about the axis of vision, the 

 image rotates in the same direction with twice the speed. If, 



NO. I2S6, VOL. 50J 



therefore, the object, say a cardboard disc with writing on it, 

 rotates twice as quickly as the mirrors or prism, it will appear 

 to stand still. This might be applied to investigate the efiects 

 produced upon bodies by rapid rotation. Another peculiarity 

 is that such an instrument will reflect rays falling upon the 

 hypotenuse at any angle up to 45' to the same spot. By 

 rotating such a prism about a line at right angles to its edge 

 and to its hypotenuse the author was enabled to reflect the 

 light from an electric lamp through a distance of I km. with 

 ease and certainty. 



Ix a communication to the EUctiician, Prof. Fitzgerald criti- 

 cises Ilerr Lenard's last paper, a short abstract of which ap- 

 peared in Nature for May 31, 1894, p. 114. In a former note 

 on Herr Lenard's previous paper, Prof. Fitzgerald had pointed 

 out that the experiments so far would be consistent with the sup- 

 position that the cathode rays were rays of light of very high 

 frequency, except for the fact that they were deflected by mag- 

 netic force, a phenomenon of which we have no other evidence, 

 and which makes it practically impossible at present to suppose 

 that cathode rays are of this nature. It was further pointed 

 out that if this deflection were an action on the emitting surface, 

 and not on the ray, it might be again possible to explain these 

 cathode ra)s by the supposition that they are rays of light. Herr 

 Lenard's more recent experiments seem entirely at variance with 

 any such supposition, while Prof. Fitzgerald considers that 

 there is nothing in them th it, in the same conclusive way, proves 

 that they are not streams of elecuified molecules or atoms. Fro.Ti 

 Herr Ltnard's observation that the dtfleclion of the ray depends 

 on the pressure of the gas in the tube in which the rays are 

 generated originally, and not on the nature and pressure of the 

 gas in the tube in which deflection takes place, it follows that, if 

 the rays are paths of projectiles, they must either pass through 

 the window, or else be projected from it, by some ac'.ion which 

 behaves like a blow given to it from the other side. .\ study of 

 the spectrum of the cathode light might settle whether any of 

 the molecules actually traversed the partition. The fact that 

 there is no increase in the pressure within the tube only shows that 

 as many molecules traverse the partiii jn in one direction as in 

 the other. Blows delivered on one side of a plate would pro- 

 ject molecules from the other side, with different velocities 

 depending on the nature of the blow and on the mass of the 

 molecule, so that a hypothesis of this kind would be quite in 

 accord with Herr Lenard's observations. The fact that the 

 magnetic effect is independent of the mass of the molecule 

 struck is explicable by supposing the electrical charge to be the 

 same for all molecules. Even though sufiicient reasons were 

 forthcoming for rejecting the theory that these rays are due to 

 projected molecules, Prof. Fitzgerald considers that there are 

 other possible suggestions which are worthy of consideration, 

 such that they are straight Grotthiis chains of molecules which 

 bend under magnetic force. This might account for a velocity 

 of propagation of actions along them, comparable with the 

 velocity of light, without requiring the component matter to 

 move with this velocity. In fact, until the residual matter 

 within the tube has been reduced very much beyond what has 

 been attained, and it has been shown that these phenomeni in- 

 crease instead of diminish, and that there is no very slow pro- 

 jection of the material of the plates, such as darkens the glass 

 in glow-lamps, it will be very difficult to prove that any of the 

 phenomena hitherto observed are due to the etlier, and not to 

 the matter present. So far the phenomena described are 

 quite like those that would be due to moving electrified 

 matter, and the actions are quite unlike anything we kno# of 

 the properties of the ether. 



The anomalies which are constantly observed in culture 

 for bacteriological researches have, up to the present, beea 



