IM 



NATURE 



[September 30, 1915 



method was developed very largely by Prof. 

 Peddle, of the Rose Polytechnic Institute, U.S.A., 

 and his method of treatment has been followed 

 by the author of the little book before us, with 

 some variation in details. In this system of 

 plotting- scales of the variables involved are set 

 off along parallel lines, and a straight-edge laid 

 across the lines enables one of the variables to 

 be determined when the others are given. The 

 author describes methods to be followed when 

 there are three, four, or more variables, and gives 

 illustrations of the plotting of reinforced concrete 

 qolumn, boiler shell, steel beams, shafts, and 

 other engineering formulas. 



Most of the illustrations are clear and easy 10 

 rfead ; Figs, i and 2 are exceptions, the lettering 

 and printing being poorly executed. There are 

 very many problems of a repetition character in 

 engineering, and much time can be saved by 

 charts of this kind. There is also less risk of 

 error in the results, once the chart has been cor- 

 riectly drawn. We can commend the book to 

 engineers who wish to make themselves 

 acquainted with this labour-saving device. 



LETTERS TO THE EDITOR. 



[The Editor does hot hold himself responsible for 



■ opini-ons expressed hy his correspondents. Neither 



, can he undertake to return, or to correspond with 



the writers of. rejected manuscripts intended for 



this or any other part of Nature, No notice is 



taken of anonymous communications.] 



Mathematical Printing. 



Your remarks in Nature (September i6, p. 79) 

 relating- to the Important suggestions on mathe- 

 matical printing recently circulated by the London 

 Mathematical Society, are confined to the examina- 

 tion of special points, in the light partly of applica- 

 tion to the special case of an analytical memoir on 

 dynamics of aeroplanes. 



It is worth while to direct special attention to what 

 is periiaps the main recommendation, for examples 

 of Its disregard are still conspicuous. The Introduc- 

 tion of the notation of the solidus or oblique bar 

 for fractions has had much to answer for, especially 

 in this country, on account of its use In excess — for 

 example, in reducing long formulas to the deal-level 

 of a -single line, thus obscuring their structure with- 

 out any compensating gain. As originally revived by 

 Sir. George Stokes, and largely adopted on his sug- 

 gestion, the Intention was to render possible the print- 

 ing of brief expressions Isolated In the current text or 

 elsewhere, without disturbing the line ; Its use for 

 reducing a formula already specially set out, and In- 

 volving a sum of fractions, to a single line of type, is 

 usually to be deprecated. 



The suggestion to replace the dot over a letter, the 

 Newtonian symbol of its fluxion, by an accent follow- 

 ing it, was put forward, doubtless with regret, as the 

 lesser evil. If only printers would provide special 

 types with the dot attached for the small number of 

 letters likely to be thus affected, no change would be 

 necessary. Joseph Larmor. 



.Cambridge, September 24. 



Palaeolithic Man in South Africa. 



I HAVE read In Nature of August 5, just received, 

 Mr. F. W. FItzsImons's letter referring to the dis- 

 covery of Palaeolithic man in South Afi-Iea. I would 

 not trouble you with these lines were It not" that many 

 NO. 2396, VOL. 96] 



of Its statements are erroneous. Moreover, owing to 

 my name being mentioned in connection with a de- 

 tailed examination which is being carried out in this 

 museum, it might be thought that I am in part 

 responsible for the conclusions which Mr. Fitzsimons 

 enumerates. As a matter of fact, I Informed him, 

 when first the skull was sent to us, and again some 

 nine months ago, that the fragment was not referable 

 to the Neanderthal type. There is, therefore, no more 

 justification In the statement he makes that there is 

 "a close resemblance In shape, thickness, and 

 measurements" of the Boskop to the Neanderthal 

 than In his generalisation on the origin of the 

 Pala^olithIc Implements In South Africa, or in the 

 state of mineralisation of the relic — "The skull is as 

 completely fossilised as the Karoo fossil reptiles," 

 which are Permian and Triasslc. 



The result of a preliminary investigation of the 

 skull by our palaeontologist will be read shortly before 

 the Royal Society of South Africa. Until then I can- 

 not give any details beyond referring those interested 

 In the subject to a short note by Prof. Boule in 

 L' Anthropologic (vol. xxv., September-December, 



1914, p. 595). L. PERINpUEY. 



South African Museum, Cape Town, 



Cape of Good Hope, September 2, 1915. 



The Aurora Australis of June 17, 1915. 



It Is Interesting to learn, as a complement to the 

 description of the Aurora Borealls by Prof. Barnard 

 In Nature of July 15 as accompanying the magnetic 

 storm of June 17, 1915, that a display of aurora was 

 also observed in the southejn hemisphere. My corre- 

 spondent, Mr. W. E. McAdam, writes: — "Upon that 

 day (June 17) there was an exceptionally fine display 

 of the Aurora Australis visible all over New Zealand. 

 Here at Dunedin It commenced at 7.30 p.m., and 

 lasted till midnight. The glow In the southern 

 horizon was quite uncanny In effect, producing the 

 Illusion that the sun was about to rise in an impossible 

 quarter of the sky, and at an Impossible hour. I have 

 been resident in the Southern Hemisphere off and on 

 for over fifty years, and have never seen anything to 

 equal this last'display of the Aurora Australis, a some- 

 what rare phenomenon in the latitude of Dunedin, 

 46° south." A. L. Cortie. 



Stonyhurst College Observatory, Blackburn, 

 Lanes, September 25, 19 15. 



Distances at which Sounds of Heavy Gun-firing are 

 Heard. 



Being much Interested in the question of the 

 distance of propagation of the sound of the firing of 

 big guns, I should be much obliged to any readers 

 of Nature who could send me some personal observa- 

 tions on the matter, or let me know whether (and 

 when and where) any notices on the subject have been 

 published. Exact references are wanted, as I should 

 try to get the papers containing the information. The 

 gun-firing from the Belgian coast is probably heard 

 in England at times. How far Inland? AH Informa- 

 tion will be gratefully received by me. 



Henry de Varigny. 



18 rue Lalo, Paris, September 17. 



Nodules on the Intermediate Bladderwort. 



Mr. H- Evans (Nature of September 23, p. 88) 

 should refer to Hooker's "Student's Flora," p. 311, 

 Ufrlcularia, "propagated by hybernacula " ; and to 

 Bablngton's "Manual of Botany," p. 339, Utricularia 

 intermedia "Increasing by buds at the end of the 

 shoots and seldom flowering." 



ElEONORA ARMI-tAGB.' 



Dadnor, Ross, Herefordshire,^ September 25» 



