296 



KNOWLEDGE 



[Fkii. 3, 188:,'. 



Ifttrrd to tbr (Cliitor. 



[Th* Khutor do0s nni koU Mm»e{f rfrponnlU/or /Mr opii 



Bt mmt'f 'inji-rl li /■ (■> rrtnrrt munuscrtf'ts or to corrrtyti ._ _ ,. _. 



roflinx' ! ' ' I* »\ori as fo$*ibU, cvruistenttjf with full and eUar wtate- 



Ati i itiotu fMoHiJ h* a.Urettfd to fkr EJitor qf KkowlRDOK; 



ii'i i/ ' i'li* to tk* PubltMhrrf, at th* OJicr, 7l, Great Qufen- 



,fr*rt, M ( 



AU RrmiUaHt^, CkftfufB, and Po»i-Offic» Ordfr$ thotUd he mad* pawahU to 

 IttMTt. Wwrnan ^ Sons. 



*,* All uU*r$ to tkf SJitor ttiH bf Numherfd. For eonrfmi^ne* of reffrmri'^ 

 corr*»pon.lmts, rk^m re/erring to anj/ Utter, wiU ohligt fcy mentioning its number 

 and the p^i*je on trkwk it appeare. 



AU L^trrt or Qm^rtfi fo tks Editor wkick r^tiire att^tttion in tke ettrrent i**H* of 

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 the dag <^ publication, 



" In knowlMl^, ilut nuD odIt i* to b^ C0Dt«mnM and do«pMc4 vho Ib not in % 



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"Tbpr« 14 no hju-ni in making a mintakp. bat grpat harm in making none. Show 

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©MX Coiirgponiitnre Columns. 



TELESCOPE. — VOLCANIC PROJECTILES.- THE EARTH'S 

 INTERIOR. — WEATHER FORECASTS. — ANCIENT MAN 

 (AND MODERN WORMS.)— " THE STARS IN THEIR 

 COURSES." 



[265] — " A Country Solicitor " (letter 237, p. 27.5) is quite right 

 with reference to the superior hundincss of a refractor, and if ho is 

 willing to spend, as he says, £60 in the purchase of an instrument 

 which ho desires to bo able to move about with moderate facility, I 

 should think that a tirst-clas.s 3 J in. telescopoon a jiortable universal 

 equatorial mounting, surmounting a strong and heavy tripod stand, 

 would be the very thing for him. This would enable him, as ho 

 says, to go through Webb's "Celestial Objects" with profit and 

 advantage. He would not, of course, bo able to see all the objects 

 described in the fourth edition, as some of them are definitely stated 

 to be tests for instruments of largo aperture ; but he would lind 

 that a largo proportion of the double stars and nebula- included in 

 Webb's lists would be well within his reach. I should be tempted 

 to insist upon the equatorial mounting, as, apart from the ease and 

 comfort of following a star by a single motion, many objects arc 

 unrecognisable without it. On the other hand, for less money, my 

 querist might obtain a 6.} in. reflector, e<)natorially mounted, too, 

 which would give him superb views of tho moon, planets, clusters, 

 Ac. ; but this would be a massive affair, and there is always the 

 nuisance of tho mirror requiring ro-silvei-ing at longer or shorter 

 intervals. 



Mr. lionso (letter 242, p. 276) may rest thoronghly assured that 

 there is not an atom of foundation for the beliof that a, stone — or 

 anything else— has over been projected from a terrestrial volcano 

 at the rate of Cy Wj miles a second, the velocity needed to carry it 

 into infinite space. Tho secx)nd part of this question is unanswer- 

 able, bccau.so tho sup])03ititious matter would never get out of tlio 

 sphere of tho earth's attraction until it got within that of some 

 other body, and your corri'spondcnt does not say what that body 

 is. If it be the moon, a projectile need only travel 2,ltl,;i3G miles 

 above the earth ! The query with which he concludes may be 

 answorod by saying that it has not boon " proved " by astronomy 

 that the earth is solid throughout, but that such solidity is rendered 

 probable from the faot that she resists the tide-producing action of 

 Uie moon exactly as a solid globe would do. Sir William Thomson 

 has (according to Nowcomb) shown that even were tho earth less 

 rigid than steel, itwoulil.so to speak, e.thibit tides itself, or bo drawn 

 out into an elliptical form ; and then, earth and ocean moving 

 together, we should have no tides at all. Moreover, the phenomenon 

 of precosiiioD (now l«'ing described and explained in those pages bv 

 the editor) conid scarcely occur were there nothing but a thin shell 

 of rocky crust covering the molt< n interior of tho globe, as euch 

 shell wonid slip round the fused nucleus, tho liquid, in course of 

 time, rotating in one direction, and tho crust iu another. Doubt- 

 less there are great cavities tilled with molten matter, but these aro 

 insignificant oompanxl with tho size of tho whole earth. 



That " the Americans have not attempted to foretell fijie harvest 



weather, or settled weather of any kind" (as stated by Mr. Don- 

 bavand at the conclusion i^f lctt<T 217, p. 277), is the vorj- rcasnu 

 why 1 |ilac« a oTlain amount of iTedooc<- in their predictions, 

 llarometric indications of u gulo afford the most absoluioly certain 

 data which exist for predicting a nietoorologioal phenomouon. Our 

 own Meteorological (Jflicc gives us wild shots because they luive to 

 say something ; the Americans many fairly trustworthy ones, 

 because they have something to say. 



Is Mr. Snell (reply 84, p. 279) thoroughly sure that the inter- 

 calated quartzose saml and loam of tho Nile Valley is tho habitat of 

 worms? — because I am not. 



I do not know whether the work is out of print, or whether (as 

 is exceedingly probable), Mr. Bazley's own modesty has prevente<l 

 him from referring in reply 184 (p. 279) to hi.s own most beautiful 

 book, " Tho Stars in their Courses." While heartily endorsing his 

 recommendation of Proctor's " Library Atlas," which 1 regard aa 

 by very far tho best one existing for the jjurjxjse for which it wa» 

 designed, I may yet say that 1 equally look upon " The Stars in 

 their Courses," as unparalleled as a means of leuming the face of 

 the sky. A Fellow of tub Royal Astkonumical So'.iety. 



AVEATHER FORECASTS. 



[256]— The remarks of Mr. Spiller (letter 12t, p. 110) and 

 " F.R.A.S." (letter IC-t, p. 207) ought not to pass ^without protest. 

 The British predictions an- not so bad nor the American ones so 

 good as they represent, neither can the former be said to be mere 

 "guess work," as insinuated by "F.R.A.S." The British fore- 

 c^ists, on tho contrary, exhibit a large advance from a few years ago 

 in our weather knowledge, and the general success which un- 

 doubtedly attends them is (juite satisfactory to those who compre- 

 hend the grave difficulties of the subject. Prediction, in these 

 islands, can never be otherwise than of a " general " character, and 

 those who insist upon a particular forecast for every town, village, 

 and villa in the United Kingdom, richly deserve the inevitable dis- 

 appointment. The medical profession at times forecast the appear- 

 ance of seasonable epidemics and the districts where they will 

 appear, but what sane person would insist upon their walking over 

 the said district and proving their prophetic in.stinet by pointing 

 out tho particular streets or houses where casi s will occur. But 

 meteorologists are asked to decide such miuutiu', and Messrs. Brown 

 & Co. think it very hard that the thunder-storm occurring in their 

 particular back gardens was not duly set forth in the day*s bulletin. 

 The fact is, that whilst the weather over dofined districts maintains 

 the same general features for a time, those features are subject to 

 endless modification of a local character. More jtiirticularly is this 

 the case with rain-storms, the non-prediction of which, by-the-bye, 

 seems the only instance of failure given by Mr. Spiller. I have 

 known rain-storms break out over areas of groat extent, and within 

 such areas there havo been parts deluged and other parts with the 

 finest weather (an instance occurring to my mind is the \Vhit 

 Monday storm, May 25, 1874). 1 remember, too, during an 

 e.'icossively rainy autumn, a year or so ago, a "meteorologist ' 

 denying any unusual fall during the period, because hid rain gauge 

 had shown nothing extra. Again, I may mention au instance where 

 tho day's return from a certain district showed "very dry" weather, 

 except at one station therein, where they had a whole month's rain 

 in the twenty-four hours. Supposing anothor storm to occur like 

 that on May 25, 1874, would Mr. Spiller or " F.R.A.S." expecv 

 tho Department to say in what locality tho rain would fall and in 

 what it would not ? 



Singularly enough, your correspondonts negative their own criti- 

 cisms by tho admiration they express for the American newspaper 

 cablegrams. Putting aside tho fact that they are quit« as often 

 " out" in their forecasts as our prophets are said to be (indeed, up 

 to date — Jan. 18 — four successive storms of theirs have failed to 

 turn up), I must point out that the Americans take three days in 

 point of time, and a coast-line extending from Spain to Norway 

 within which their storms .are to appear j and this, too, when tlie 

 prediction is made after the storms have an actual existence. Will 

 Mr. Spiller or "F.R.A.S.'' grant our own men ecju.'il indulgence? 

 Three days' grace and almost unlimited areas for the fulfilment of 

 their pr>>|)hocies ! Surely, after this, our own seers have little to 

 bo ashamed of ! 



I am not here dis])ai*aging tho American warnings, for they fulfil 

 to the letter my idea of what these forecasts must ever be — namely, 

 general outlines both in respect to area and time. Beyond this, it 

 is impossible at present to go, and, looking at tho nature of tho 

 subject, I do not think we shall ever advance much further. In the 

 meantime, it is to bo hoped we shall not pour the whole of our felici- 

 tatious upon foreigners, but accord some meiisnre of praise to our 

 own men, who have certainly not been less successful, and who. it 

 is equally certain, have a much more difficult problem to deal with. 



Ar.nKRT P. HoLBBic. 



