March 24, 1910J 



NATURE 



107 



and laborious compilation by M. Ernest BUn of Remarques 

 meteorologiques made in various districts of that depart- 

 ment between the fifteenth and eighteenth centuries. The 

 notices are taken from the archives of various institutions 

 and from provincial publications, and are arranged in 

 chronological order, with references to the sources of 

 origin, and furnish much information on the general 

 character of the seasons and on conspicuous meteorological 

 occurrences, floods, &c. Some interesting references are 

 also made to the former practice of ringing church bells 

 with the idea of dispersing hail and thunderstorms ; this 

 practice was still in vogue at Quarr^-les-Tombes until the 

 middle of the nineteenth century. The publication of this 

 summary is due to a suggestion by M. E. Lauda, of the 

 .Austro-Hungarian Hydrographical Service, and recom- 

 mended by the Meteorological Conference at Innsbruck in 

 1905, that all available historical documents of dififerent 

 States regarding abnormal weather phenomena should be 

 collected and published. 



Im November last Mr. J. W. Giltay and Prof. M. 

 de Haas communicated to the Koninklijke -\kademie van 

 Wetenschappen te .Amsterdam an interesting paper, a copy 

 of which has just reached us, on the motion of the bridge 

 of the violin. Various statements as to the nature of the 

 movement have been made by writers on acoustics, such 

 as Helmholtz, van Schaik, .\pian-Bennewitz, Barton, 

 Garret, and Pentzner, but, by ingenious experiments, 

 Giltay and de Haas have conclusively proved that the 

 motion of the bridge is in tw^o directions, namely, (i) in 

 its own plane about one of the feet and at right angles 

 to the strings, and (2) at right angles to its plane, or 

 transversely, that is, in the same direction as the strings. 

 The sound of a violin must be attributed to three causes : — 

 (a) a vibration imparted to the air by the string; (b) a 

 vibration which the roof of the violin receives from the 

 parallel swing of the bridge ; and (c) a vibration com- 

 municated to the roof by the transverse vibration of the 

 bridge. The (a) movement may be left out of account 

 as being very weak, and the intensity and timbre of the 

 note is determined by the parallel and transverse motions, 

 and more especially by the latter. Each of these motions 

 has its fundamental tone and associated partials, and the 

 quality of the tone is modified when the intensity of one 

 of the motions alters its partials, while it may leave the 

 other motion unchanged or slightly changed. A " mute " 

 damps the transverse motion of the bridge to a higher 

 degree than the parallel motion, and the use of the mute 

 does not weaken intensitj- so much as to alter quality. 



The February number of the Johns Hopkins University 

 Circular consists mainly of notes from the physical labora- 

 tory- of the Universit)-, edited by Prof. J. A. Ames. One 

 of the most interesting of the notes is that of Mr. J. A. 

 .Anderson, on a method of testing screws intended for the 

 most accurate work, such as the ruling of diffraction 

 gratings. A nut which fits the screw accurately is cut in 

 two by a plane through its centre perpendicular to its axis, 

 and the two parts rotated through an angle of 180°, for 

 example, with respect to each other. One of the plates of 

 a Fabry and Perot interferometer is mounted on each half 

 of the nut, and the motion of the interference fringes 

 observed as the screw is rotated by hand at a convenient 

 speed, the two parts of the nut being prevented from 

 rotating with respect to each other. The method is more 

 sensitive than that of the late Prof. Rowland, which con- 

 sisted in ruling two sets of grating lines at a small angle 

 to each other and observing the loci of the intersections 

 of the two series of fines. 



NO. 2108, VOL. 83] 



The Electrician for March 4 contains a short article by 

 Dr. W. H. Eccles on the radiation from directive aerials- 

 in wireless telegraphy, in which the problem is treated by 

 the exponential method, which has done so much to* 

 shorten the mathematical work in modem treatises on 

 light. If the disturbance at the point of observation due 

 to an aerial at a distance x is represented by rc"''^*\ 

 where u is a linear function of x and of the time, that 

 from another aerial at a distance d from the former in a 

 direction which makes an angle ^ with the line joining^ 

 the point of observation to the first aerial can be repre- 

 sented by a similar expression, with r and a omitted and' 

 tt decreased by 2vd. cos <^.f\. The total disturbance at- 

 the point of observation due to the two aerials can then 

 be represented by -f'^fr/" + <?"'"''• ^"**'*). The energy re- 

 ceived is the square of the modulus of this, that is, 



1^+ i + 2rcos{a+2rd. cos ^./X). 

 This expression, plotted as a function of ^, gives the 

 polar diagram of the directive system, the form of which 

 depends greatly on the value of 2*df\. The directions in 

 which the radiation from the aerials is a maximum for 

 a given value of a, the relative phase, are independent 

 of r, the ratio of the amplitudes of the oscillations in the- 

 two aerials. 



Although users of glass apparatus are familiar with- 

 the general appearance of the breaks which sometimes- 

 occur, no one has hitherto made a scientific study of their 

 fonns in relation to their causes. In the Physikalische 

 Zeitschrift for February 15 tfiere is a paper by Dr. L. 

 Gabelli which remedies this omission. Breaks are classified 

 as due either to external or to internal causes. The 

 external causes may be localised, as in the case of a blow- 

 struck on the surface of the glass with a pointed or blunt 

 object, or be distributed over the surface, as in the case of 

 hydrostatic pressure. The author shows by means of numerous 

 figures that in each case the break has characteristics which 

 enable the cause to be assigned, and in the case of hollow 

 vessels there is a difference between the effects due to the 

 same cause applied within or without. Of breaks due to 

 causes within the material, those which fall under unequal 

 heating are most common, and, like the previous ones, 

 have their own characteristics, which depend greatly on 

 the distance of the heated point from the edge of the 

 material. The author hopes that the technical importance 

 of the subject will lead others to continue these investiga- 

 tions. 



We learn from a note in Engineering for March 18 that 

 the Bureau Veritas International Register of Shipping will 

 shortly issue a new edition of its rules. The new publi- 

 cation will be very comprehensive. No change has been 

 made in the method of determining the scantling numerals, 

 which remain as formerly, the basis being the sum of 

 the breadth and depth, and the product of the length, 

 breadth, and depth. For thickness of material, one- 

 fiftieth of an inch has been adopted as a unit, instead of 

 one-thirty-second as formerly. This will admit of readv 

 comparison with the British standard decimal system on 

 the one hand and with the metric sjrstem on the other. 



Messrs. Williams and Norgate will issue very shortly, 

 in conjunction with Messrs. B. G. Teubner, of Leipzig, a 

 volume compiled and edited by Yokshio Mikami, entitled" 

 " Mathematical Papers from the Far East." 



Messrs. Watts and Co. have issued for the Rationalist 

 Press .Association, Ltd., a cheap reprint of " The Nature 

 and Origin of Living .Matter," by Dr. H. Charlton Bastian, 

 F.R.S. This edition has been revised and slightly- 



