4IO 



NATURE 



L April i, 1922 



The Historical Geography of the Wealden Iron Industry. 

 By M. C. Delany. (Historico-Geographiccal Mono- 

 graphs.) Pp. 62 + 3 maps. (London: Benn Brothers, 

 Ltd., 1921.) 4^. bd. net. 



This is the first of a series of " historico-geographical " 

 monographs pubhshed under the editorship of Prof. 

 H. J. Fleure, which are to be essentially research 

 monographs. It would greatly enhance the value of 

 the series if in future numbers the matter were indexed 

 or at least paragraphed with suitable headings. A 

 single chapter of forty pages does not facilitate reference. 

 As regards its matter, however, this short monograph 

 is well done, although it is difficult to follow the dis- 

 tribution of the Wealden forest at different ages on 

 the sketch maps provided. The author traces the 

 iron industry in this part of England from its beginning, 

 in Roman days or earlier, to its decline in the eighteenth 

 century, when, as is well known, it could no longer 

 compete with the more favourably located industry on 

 the coal-fields. There appears to be a gap in the 

 history of the industry for seven or eight centuries after 

 Roman times ; at any rate, the author has been unable 

 to find evidence of its existence in that period. Some 

 interesting details are given of the methods employed 

 and the kind of iron work produced. 



Letters to the Editor. 



[The Editor does not hold himself responsible for 

 opinions expressed by 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 commuttications.'] 



Precursors of Wireless Telegraphy. 



A TRADITION is growing (of. Nature, March 9, 

 p. 316), and requires scrutiny, that it was owing to 

 discouragement by Sir George Stokes that D. E. 

 Hughes abandoned his experiments in 1879, 

 anticipatory of the methods and apparatus of modern 

 wireless telegraphy. This is in contrast to all that 

 is known of Stokes' extreme caution in advancing 

 opinions, for which in fact he has usually been blamed, 

 for example by Kelvin and Rayleigh in connection 

 with spectrum analysis. From the modest letter of 

 Hughes published in the Electrician in 1899, and in 

 Fahie's "History of Wireless Telegraphy," Appendix 

 D, which describes his very remarkable investigations, 

 such an inference could scarcely be fairly drawn : 

 " The experiments shown were most successful, and 

 at first they (Spottiswoode, Huxley, and Stokes) 

 seemed astonished at the results ; but towards the 

 close of three hours' experiments Prof. Stokes said 

 that all the results could be explained by known 

 electro-magnetic induction effects, &,nd therefore he 

 could not accept my view of actual aereal electric 

 waves, unknown up to that time, but thought I 

 had quite enough original matter to form a paper on 

 the subject to be read at the Royal Society." Hughes 

 continues that he was so dismayed at being unable to 

 convince them that he actually refused to write a 

 paper on the subject until he was better prepared to 

 demonstrate the existence of these waves, and with 

 this end in view he continued his experiments for 

 some years (Fahie, loo. oil. p. 310). 



The key to the matter has, I believe, been supplied 

 by the extracts from Hpghes' original notebooks, now 

 in the British Museum, which Mr. Campbell Swinton 

 read at the Jubilee Meeting of the Institution of 



NO. 2735, VOL. 109] 



Electrical Engineers, and which he has kindly shown 

 to me in manuscript. They show that Hughes held 

 that in some way " the effects were due to electric 

 conduction through the air " (Nature, loc. cit. p. 316). 

 Those who knew Stokes would expect that he would 

 demur stoutly to such a doctrine as misleading, and 

 would insist that " they could be explained by known 

 electro-magnetic induction effects." For it was not 

 unknown even before Maxwell's theory (1860-64) 'that 

 the inertia of such induction could propagate waves 

 along wires, which, if of very high frequency, would 

 travel, as Kirchhoff showed in 1857, with the speed 

 of light. The transcendent advance of Maxwell's 

 definite theory, confirmed as fact by Hertz in 1886- 

 1888, was that in favourable conditions such waves 

 could release themselves from the matter and travel 

 free across space ; and, more fundamental still, that 

 it is just by such free transmission that all electric and 

 optical effects become established. 



It seems clear to my mind that the affair was a 

 misunderstanding, such as can readily be imagined, 

 between the tenacity of the practical inventor and the 

 insight of the theorist who was conscientiously deter- 

 mined not to give countenance to a misapprehension 

 of the nature of the phenomena. But if Maxwell 

 had been present (he had recently died), or Kelvin, 

 who were more closely interested in the problem of 

 the nature of the transmission of electric influence 

 than Stokes, they would perhaps have used further 

 efforts not to allow the subject to drop ; though it 

 would at that tin\e have required all the resources of 

 theory to make progress along the lines of these 

 experiments. 



The episode is so interesting from the point of view 

 of the philosophy of history of scientific discovery, 

 not to mention the practical application of the 

 microphone operating by loose contacts by Hughes 

 himself, in the manner developed much later by 

 Branly and Lodge and Marconi, that a full statement 

 from all aspects should be on record. 



Joseph Larmor. 



Cambridge, March 18. 



Stonehenge : Concerning the Four Stations. 



Just within the surrounding earthwork of Stone- 

 henge there are two stones symmetrically placed with 

 reference to each other on opposite sides of the 

 centre. There are also two mounds in corresponding 

 complementary (or reversed) positions. The arrange- 

 ment is shown on the accompanying plan (Fig. i), the 

 dimensions for which have been taken from Flinders 

 Petrie's very careful measurements as published in 

 his work, "Stonehenge — Plans, Description and 

 Theories " (1880). 



For the purpose of this paper the arrangement is 

 referred to as " The Four Stations." The two stones 

 are numbered respectively (on Petrie's system) 91 and 

 93, and the two mounds 92 and 94. 



Concerning this pair of stones and pair of mounds 

 Colt Hoare remarks : — 



" There are two small stones within the vallum, 

 and adjoining it, whose uses have never been 

 satisfactorily defined. The one on the south-east 

 side is near nine feet high, and has fallen from its 

 base backwards on the vallum ; the other, on the 

 north-west side, is not quite four feet high ; both 

 rude and unhewn. There are also two small 

 tumuli ditched round, so as to resemble excava- 

 tions, adjoining the agger ; they are very slightly 

 * elevated above the surface, and deserve particular 

 notice, as they may give rise to some curious and 

 not improbable conjectures " (" Ancient Wilts," 

 i. p. 144). 



