566 



NA TURE 



October 12, 1893 



I trust that physicists will agree with me in this. J-know 

 that some Electricians try to sin in a similar way, by writing 

 610 when they mean 6 ohms. Bat with all deference to any 

 individuals who may have allowed themselves carelessly to drift 

 into this practice, it is a thoroughly bad precedent. We shall 

 soon be having 123 and i,v and '3/; for current and voltage and 

 inductance respectively; a simple specification will look like 

 algebra, and algebra will look like gibberish. 



Similarly the custom of writing M (or a millionth of an 

 atmosphere, or i barad, is a worrying custom. Let us always 

 h.ive names for units with which we have much to do, but 

 never single letters. Single letters have to serve a far more 

 important purpose, that of denoting the quantities themselves — 

 the whole of a quantity, numerical part, unit, and all. 



This last is an old hobby of mine. Ever since my brother 

 showed me the advantage of consciouily interpreting algebraical 

 symbols as standing for concrete quantities, and not merely for 

 abstract numbers, the advantage of doing so has presented it- 

 self to me with cumulative force. Most physicists are, I think, 

 now of a similar opinion, if they have thought at all about the 

 matter, and Prof. Greenhill is being left almost alone in his 

 state of grievous error ; I would say heresy, but that I fear he 

 has some of the pure mathematicians with him for company. 



I have dragged Prof. GreeHhill in because I want to deny the 

 extraordinary assertion which he makes in an article on page 

 457 of your issue for September 14, viz. that I would like to 

 " banish the word hundrediveight from our language." On the 

 contrary, for the specification of loads I have always found it a 

 very convenient word; and if architects use it thus, for pressure 

 on foundations, so much the better. I know what he is referring 

 to — a part of my book on mechanics where I am instructing 

 youth in the meaning of the term mass, and the difference be- 

 tween mass and weight. Till they are clear on this point I say 

 that "hundredweight " is a term better avoided for the present. 

 I should, for instance, recommend its avoidance for the present 

 by Prof. Greenhill. 



But to return to Dr. Burdon Sanderson's address, which it is 

 perhaps evident from a former part of this article that I have 

 been trying to read, there are two small points on which I 

 woald ask a question. First, with regard to totally colour- 

 blind vision. If a person sees all the world in shades of gray 

 he may properly be called colour-blind, in one, and that the 

 most important, sense ; but it does not seem to me to follow 

 that he necessarily appreciates white, still less that he proves a 

 specific white sense in normal eyes. On the orthodox theory, 

 as held by physicists, such an eye would strictly be called mono- 

 chromatic ; one only of the three colours would be seen, and 

 which it was would matter nothing to the seer, though it might 

 be ascertained by studying his spectrum vision which the one 

 colour was in any given case. I believe that Abneyand Festing 

 found it usually blue. But as regards the psychological impres- 

 sion produced by mono-chromatic vision on the seer, its indis- 

 criminating monotony would obviously result in total absence 

 of colour perception. One colour sensation is psychologically 

 the same as none. 



The oiherr question is wlrether it is useful to dislingnish 

 between " phy-iical light" and "physiological or subjective 

 light." The term light applies to the stimulus as far as the 

 retina, but after that is it not belter called either sight or some 

 other and more impres-ive-looking word, beginning with photo 

 or neuro and perhaps ending with taxis, signifying the specific 

 disturbance of the optic nerve and brain centres. These terms 

 light, heat, sound, &c., have always been ambiguous; but, if 

 needful to discriminate, they had better perhaps now be 

 handed over entirely to physics, to signify monosyllabically the 

 external physical stimulus ; while fresh words are coined for the 

 physiol<jgical, and again, where not already existing, for the 

 psychological, result. 



I trust that this letter has not the appearance of undue pre- 

 sumption ; the whule of it is written in the key of interro- 

 gation. Oliver J. Lodge. 



British Association : Sectional Procedure. 



Members of the British Association often entertain schemes 

 for the improvement of sectional procedure, which rarely, so 

 far as I have seen, commend themselves to the good opinion of 

 the organising committees. I beg leave to produce one scheme 

 more. Whether the remedy is practicable or not, I am quite 

 sure that the grievance I have to point out is a real one.. 



NO. 1 250. VOL. 48] 



Every member of the Association has suffered from the great 

 uncertainty as to the hour at which a particular paper will come 

 on. At the recent Nottingham meeting I was unlucky enough 

 to spend one morning to no purpose. I had a direct interest io 

 two communications ; one was not reached that day, the other 

 was taken as read. There is no care taken to prevent such 

 accidents, and yet it would have been easy to provide against 

 the second one at least by marking the communication as 

 "Title only." The other case is of greater, but not, I think, 

 of insuperable difficulty. The remedy which occurs to me it 

 this : a fixed time .should be assigned to communications which 

 in the opinion of the Sectional Committee are of special in'erest 

 and importance. There might be at least two absolute fixtures 

 in each day's proceedings, when members would know that 

 nothing would be allowed to interfere with the punctual pro- 

 duction of certain papers or addresses. I should be inclined to 

 mark these by some distinctive title, such as "Address by 

 request of the Section." It seems to me very desirable to send 

 out special invitations before the meeting to persons who couM 

 communicate interesting results, and I have little doubt that a 

 fixed time would often lead to acceptance by persons whom the 

 Sections would be glad to hear, but who rarely or never appear 

 in the programme under the existing system. What is bad for 

 the audience is bad for authors too, and after an author finds 

 that his communication is addressed only to people who come 

 to hear something else, and to people who in their despair are 

 working through the entire list, he ceases to offer himself. 



If the facilities granted to pre-arranged addresses should lead 

 to a stricter treatment of trivial papers and business matter of 

 no direct scientific interest, the Sections would not suffer. 



L. C. M. 



Orientation of Temples by the Pleiades. 



Eighteen months ago, while at the Mena House, Cairo, 

 I came across a back numlser of Nature, which contained za 

 article on "The Origin of the Year," in which reference is 

 made to the orientation of some Egyptian temples, and I 

 suggested that inquiries should be made as to whether they 

 were not in some cases oriented by the Pleiades. I had not 

 then seen the numbers that referred to stellar orientation. 



A pamphlet of 105 pp. was privately printed by mysel f //ijV/c 

 j'^ar.rae't) (I) for my own use in the prosecution of "A Com- 

 parison of the Calendars and Festivals of Nations," with special 

 reference to the Pleiades. 



Since that pamphlet, and a second, of about 20 pp. or cycU 

 regulated by the Pleiades, were printed, I have collected a grei 

 deal of further data confirming the conclusions arrived at i 

 1863. Miiller .=ays, in his Religion, &c., of the Dorians, I. 33}^ 

 that the famous eighth-year cycle, which was in general UM 

 in Greece, was luni-sidereal, and regulated by the Pleiades, aoa 

 that the great feasts of Apollo at Delphi, Crete, and ThebetJ 

 were arranged by it. He also states (p. 338) that there aijl 

 vestiges of a sacred calendar in general use in Greece in eaiif 

 ages based on this cycle, but that it fell into disuse, and, IB 

 Consequence, the Attic festivals and months were thrown into 

 confusion. He had previously staled that the Olympiads were 

 based on the eight-year cycle. Apollo, generally assumed le 

 have been essentially a solar deity, though he evidently vui 

 originally a type of Karlikeya, was a god of the Pleiades, and 

 hence the seventh day was sacred to him at Athens As thou 

 stars were the daughters of Atlas, the forty days during which 

 they deserted the nightly sky were spent by Apollo in dancing 

 and singing among the Hyperboreans of .Marias. When the 

 rising of the Pleiades at early morning took place, he returned. 

 In 1SS2, at the American Association, I showed that h« 

 is still remembered south of the Atlas as "Apolo, a good 

 god, who comes and plays upon the harp." But in tin 

 lapse of centuries the Pleiades seemed logo astray, and were for- 

 gotten, and, strange to say, Athenpaus was forced to treat 

 the history of the Pleiades as a bit of obsolete folk-lore. Ii 

 discussing the subject of the two groups of Peieiades on tht 

 handles of tlie divining cup of Nestor, he says that it is a mis 

 take to suppose that Homer by PeUiades meant "doves" (: 

 mistake which Mr. Gladstone has also made in his Homerit 

 Studies), and he explains that the cup had two clusters of sever 

 stars represented on it. Many persons, he says, are puzzled a( 

 the prominence thus given to those stars, but in early times thci 

 were regarded as very important, and left their impress on earl; 

 mythology, and he also shows that they once regulated the tini> 



