3118 



NA TURE 



[February 6, 1902 



Of course, everybody knows that the practice above alhidecl 

 to of ending a minor piece with a major chord is by no means 

 uncommon with ISach. For example, in his " (irosse- Passions- 

 Musik," the chorus which follows the duet, " My Saviour 

 Jesus now is taken," ends (according to the English version by 

 Miss Johnston) with the words, "the treach'rous betrayer, the 

 murderous throng." Bach has reiterated them — the first lime 

 with a minor chord (E), with G natural, on the word " throng" ; 

 the second time with a chord on the same key-note, but with a 

 major third (G sharp) and a pause. The effect is thrilling. 

 Surely there could have been no allowance for drop here. 

 Handel, on the contrary, begins and ends his chorus, " And He 

 shall purify," in the " Messiah," in G minor, although the two 

 succeeding pieces are in D major, with which key the previous 

 piece would have been brought into relationship by the raising 

 of the third. 



This is a digression from the subject of your correspondents 

 letters, which probably never entered the minds of the great 

 masters named. K, Freeman. 



London, February 3. 



A Lunar Romance. 



I 



to by 



s not Mr. Wells right in the description of the effect referred 

 .„ oy the reviewer of his " First Men in the Moon " (p. 218) ? 

 The sphere itself, as a whole, is not attracted by gravity. The 

 action of gravity has efifect only in the line (?) through the open 

 window, and, </«<? the sphere, would only affect that part 

 which would be directly in a straight line from the moon through 

 the window. F- C. Constable. 



Wick Court, near Bristol. 



In answer to Mr. Constable, I think we cannot allow that the 

 sphere is not attracted by gravity. I understand it to be a 

 sphere of solid glass, tq, inside a cavorite covering, RS (Fig. i). 



In the case considered, the covering is removed through a 

 wide angle AB, thus described (p. 62): "Four windows were 

 open in order that the gravitation of the moon might act upon 

 all the substances in our sphere." Hence the gravitational beam 



Gravitational 

 Beam 



reaches the whole of the glass sphere itself (Fig. 2) ; unless 

 (Fig. 3) Mr. Wells means to reserve little pieces, v\v and MN, 

 at the sides outside the beam. In this case the total mass of 



the sphere remains the same, but is not all acted on by gravity ;. 

 so that the acceleration of the whole would be /«ithan^(in 

 the ratio of mass acted on to total mass), i.e. less than that of 

 objects within, which would promptly settle to the " floor." 



If Mr. Wells was thinking in this subtle fashion I withdraw 

 my criticism, and Mr. Constable will see that I have left an 

 open door for myself in the review for withdrawal. I may say 

 it was left open expressly in view of this possibility. But the 

 context does not suit this view at all well. 



The Reviewer. 



Cherry Leaf Disease. 



The question raised by Sir W. T. Thiselton-Dyer's letter is a 

 very important one, and I venture to offer a few observations 

 on it. 



It is impossible that Mr. Bennett — still more Mr. Carruthers 

 — could have intended to suggest that the experts at Kew and 

 the British Museum are not competent to investigate such 

 diseases as the above when they are submitted to them. They 

 probably meant that an organised system is wanted in every 

 county, by means of which an outbreak of any such disease 

 should be at once brought under their n<itice. This could only 

 be satisfactorily done by local inspectors, who would be in 

 touch with the farmers on the one hand and the experts on the 

 other. It should be part of their duties to keep accurate 

 records of temperature and rainfall in order to show the con- 

 nection, if possible, between these and the disease. These 

 officials would naturally be appointed and paid by the County 

 Council. 



As regards the outbreak of Gnomonia mentioned by Sir W. T. 

 Thiselton-IJyer, it is a curious fact that in most of the orchards 

 about here affected by it in 1900 the disease has almost dis- 

 appeared, though no preventive measures .such as stripping the 

 leaves were taken. It would, however, be very unfair to blame 

 the advisers of the Royal -Agricultural Society for raising a false 

 alarm ; in the case of a disease not known to have occurred in 

 this country before, they were clearly bound to act upon the 

 best information they could get — that of Frank — and warn the 

 farmers. The more equable climate of England, as compared 

 with Germany, is probably the cause of the different result, 

 the effects of comparatively small differences of temperature 

 and moisture being vastly more important than is generally 

 believed. 



Ai,FREi) O. Walker. 



Ulcombe Place, near Maidstone, February 2. 



Extremes of Climate in the British Empire. 



VouR correspondent (p. 299) who writes under this head 

 in the current number of Nature would make the labours of an 

 editor as super-Herculean as those of the Highland minister 

 who was called upon to incorporate the whole body of divinity 

 in every sermon lest his flock should be misled. 



That it would be wrong to generalise on the climates of the 

 British Empire from eighteen stations, or to claim any one of 

 them as the hottest or the wettest point, is obvious : but even in 

 the few lines of your abstract you have not done this, and in my 

 original summary (Symons's Meleorological Magazine, Novem- 

 ber, 1901, p. 167) I said : — 



" It is true that neither the hottest, the coldest, the wettest 

 nor the driest points in the Empire are dealt with ; and the 

 reader is warned, as on each previous occasion of presenting 

 this annual summary, not to take the figures as meaning more 

 than they profess to convey." 



In order to secure continuity in the records, which are pub- 

 lished monthly, it is necessary to obtain them from regular 

 observatories : these are, unfortunately, few ; but, fortunately for 

 the student of climatology, they are usually situated in districts 

 of normal rather than of extreme climate. Additional observa- 

 tions would certainly be welcome, and I hope during the 

 present year to be able to publish monthly records from at 

 least twenty-five stations in all the Britains. 



Ht'GH Robert Mill. 



62 Camden Square, London, N.W., January 31. 



Elementary School Mathematics. 



In connection with the present discussion on the teaching of 



elementary mathematics in schools, and the recommendation 



made by many experienced teachers that much use should be 



made in geometry— at any rate in the earlier stages of actual' 



NO. 1684, VOL. 65] 



