Nov. 11, 1881.] 



• KNOWLEDGE * 



35 



JTEF . '.: "r-sr?f 



IfttfrsJ to t()f emov. 



{The Editor doe» not hold Mm$elf retpontihU for the opinions of Aw corretpondentt, 

 B.e cannot undertake to retur^n tnanutcripfg or to correrpond with their vriteTS. Se 

 rtquest* that all comrhunication* gkould tte on short af possible, conttnt&fttli/ icith full 

 and etear MtatemenUt qfthe vriter'a meaning.'] 



All Editorial eommunicatioHa ahould be addre$aed to the Editor <if Kxowledgb ; 

 all BuMineta communications to the Fublishers, at the Office, 7-1, Qreat Q,ueen- 

 street, W.C. 



All Semittancef, Cheques, and Fott-OJice Orders should be made payalle to 

 Mestra. Wi/man 4" Sons. 



•^•All Utters to the Editor mil be Xumbered. For convenience of reference^ 

 eorrespondenta, vhen rtferritiff to any letter, icill oblige btf mentioning its number 

 and the page o» tchich it appears. 



All Letters or Queries to the Editor tehich require atiention in the current issue of 

 Ksowi.BDaB, thould reach the Fubtiahing Office not later than the Saturday preceding 

 the day qf publication, _____^ 



" In knowledge, that man onlr is to be contemned and despiaed who is not in a 



Btate of transition Xor is there anything more adverse to accuracy 



than fixity of opinion." — Faraday. 



"There is no harm in making a mistake, but ^eat harm in making none. Show 

 me a man who makes no mistakes, and I will show you a man who has done 

 nothing." — Liebig. _____ 



©\\v (CoiTfSjpontinur Columns. 



THE 1-INCH MAP OF THE ORDNANCE SURVEY. 

 [4] — From timo to time we hear expressions of admiration at 

 the beauty and fidelity of those maps of Great Britain and Ireland, 

 based upon that {^rcat Trigonometrical Survey, which really began 

 in 17S1. In fact, an "Ordnance 3Iap" is with many people a kind 

 of synonym for all that is topographically acciu-ate in the shape of 

 cartography. I venture, however, to express my belief that praise 

 is bestowed upon these maps — be it observed that I am now speak- 

 ing only of those on the scale of 1 inch to a mile— I say, I believe 

 it will be found that praise is bestowed upon them in the inverse 

 ratio of their employment for purposes where minute accuracy is 

 essential. I have said that the suney began in 1781, because it 

 was in that year that the Triangulation for correcting the Observa- 

 tories of Grecnmch and Paris was commenced by the measurement 

 by IGeneral Boy of his famous base of 27,10t feet on Uounslow 

 Heath. I believe, however, that what is now known as the 

 Ordnance Survey had its beginning in 1701, when proceedings were 

 initiated by the remeasurement of the base of which I have just 

 spoken, by Colonel Williams, Captain JIudge, and Mr. Dalby. As 

 an illustration of the maimer in which, up to a pretty recent period, 

 the maps on which I am commenting were ])rodnced, I may hero 

 say that one purchased within a comparativch' few years lies before 

 mo as I write, and bears npon the upper jiart of it the legend, 

 " Published 1st February, 1813, by Lieut. -Colonel Sludge, Tower." 

 Now, it is abundantly evident from this, that an old plate 

 must have been worked upon and patched up year after 

 year, alterations being engraved somewhere about the place 

 in which they had occnrrcii ; but, as I shall immediately 

 show, they seem to have been put in merely by eye, so 

 erroneous are a large proportion of the minor details when 

 tested with minute precision. To give a single illustration : the 

 mark + stands for a church ujaon these Maps ; but a query as to 

 ■whether the intersection of the arms of the cross gives the site of 

 the spire (the conspicuous part from which it might well be sup- 

 posed that all measurements would be made) is always met at the 

 head office at Southanijiton by the reply that the cross is merely a 

 conventional sign, and does not represent any part of the church in 

 particular ! Another stock answer, too, to complainants at head- 

 quarters is that distortion arises from shrinkage in drying 

 the maps : such shrinkage being unequal, and dependent upon 

 the manner in which the maps are hung up to dry after 

 printing. Whence it would appear that after between 70 and 

 80 years' practice and experience, the combined science of the 

 entire staff at Southampton is ilnequal to provide for the equable 

 shrinking of a sheet of damp paper. I have been led into 

 these remarks by a recent piece of personal experience, in the 

 shape of the attempted identification of all the chief objects visible 

 from a height, by the aid of a 1-in. Ordnance Map and a 6-in. 

 transit theodolite. One observation will suffice to illustrate the 

 ground of my complaint. It is that of a large and conspicuous 

 church-tower, Si miles from the place of observation ; the angle 

 between which and the meridian differed 51', as measured by the 



instrument and on the map ; 51', 8 J miles off, representing, 

 it is almost needless to add, about 7067 feet, or 235i yards. The 

 fact seems to be that, while the greater triangles have been sur- 

 veyed with all the refinements of Geodetical science, the filling in 

 of the details has been done " anyhow." I have, I verily believe, 

 seen quite as accurate plans made by pacing, and with an 

 ordinary prismatic compass. Such of the 25-in. maps as 1 havo 

 examined really do seem to afford remarkable examples of pains- 

 taking correctness; and I am informed that those on the 6-in. scale 

 are equally i^raiseworthy. Moreover, 1 learn that a new scries of 

 1-in. maps, reduced from this 6-in. survey, arc in tlie course of pub- 

 lication. If this be so, wo may live in hope that we shall some day 

 be in possession of a series of portable maps, vieing in accuracy 

 with those issued by the German and other Continental Govern- 

 ments. Meanwhile, let no one go into a shop to inirchase one of 

 the present 1-in. Ordnance Maps under the impression that he will 

 receive a rigidly correct chart of the region professed to be repre- 

 sented : because he will not. 



A Feliow of the Royal Asteonomicai, Society. 



IS THE SUN EOT? 



[5] — Will you permit me to remark that " Anti-Gucbre's " letter 

 (No. 1., p. 15) is in some respects a repetition of an article of mine 

 entitled " The Astronomy of the Future," which appeared in Fraser's 

 Magazine, Nov., 1876, since published in a volume, "Pith," in 

 which I endeavoured to maintain that, in spite of the revelations of 

 the spectroscope, the theory that the sun is incandescent is wholly 

 untenable and improbable. My reasons for thinking so are given at 

 length in the paper mentioned ; but perhaps it may be as well to 

 repeat here that if we start with the supposition that the sun is a 

 gigantic galvanic battery, there can bo no more reason for believing 

 it to be red-hot, than there is for assuming that the battery we use 

 in our laboratory is a sort of fiu'nace. 



Light and heat are surely phenomenal products, caused by 

 magnetic and electrical forces, in a state of intense activity, acting 

 U))on atmospheric conditions ; so that we are at perfect liberty to 

 maintain that Mercury need not be any warmer or more iUuminated 

 than is our earth or Jupiter. The sun may possess the power of 

 producing the phenomena of incandescence, without itself being 

 incandescent. 



The inflammatory action apparent on the face of the sun may be 

 merely the chemical conversion of substance into force ; and if we 

 could see the working of a dilute acid on the surface of the 

 metallic plates in a galvanic battery, we should probably discover 

 on a minute scale a corresponding commotion to that which is so 

 conspicuous on the snn. 



As stars differ from each other in their material composition, it 

 is only natural that the revelations they make of themselves in the 

 spectroscope should be also constitutionally different. — Yours, Ac, 



Newton Ceosland. 



[6] — You wish for more reasons in favour of the sun's being a 

 cold body. Why is it that, although we have reflected sunlight from 

 the moon, we do not see that light on its way to that body ? 

 Surely there would be a broad flood of effulgence along the heavens. 



Tyro. 



INFLUENCE OF SEX ON MIND. 



[7] — Permit me to take exception to the title of the article 

 " Are Women Inferior to Men ?" To hold that woman's mind is, 

 like her body, naturally weaker than man's, does not imply absolute 

 inferiority. Overwhelming evidence to prove woman intellectually 

 weaker than man can be classed under five heads : — 1. Anatomical. 

 — Head-forms, shape of skull, size of brain. 2. Physiological. 

 — Woman is always, more or less, an invalid. Hence, if supposed 

 equal to man in intelligence, she is hearily handicapped by her 

 physical organisation. Sex must influence mind. 3. Historical. 

 — If the sexes are equal in mind, why has man's intellectual work 

 so far surpassed that of woman ? Why was not the alleged sexual 

 mental equality asserted and proved long ago ? 4. Daily Ex- 

 perience that women cannot argue, and never see more than rne 

 side of any question. 5. Woman's Superior Instinct; a decisive 

 proof that she has less reason than man. 



The subject is highly interesting and important, as determining 

 woman's proper sphere and education. If permitted, I would 

 gladly place my views concisely before your readers. 



N'j'c. 5. Yours, &c., J. McGeigoe Allan. 



[Certainly. — Ed.] 



THE NOVEMBER METEORS. 

 [8] — In your first number you invite correspondence, and I there" 

 fore make no apology for writing and suggesting that, as yoiu' pub- 

 lication is intended for begiimers in science, it might be an advantage 



