Oct. 12, 1882] 



NATURE 



573 



fog in London, ihe knowledge of this rain-band would not help 

 him much, for he knows by his chart that rain has already 

 set in. 



What he does want to know is whether the cyclone will move 

 northwards, eastwards, or southwards. This no prognostic can 

 tell him ; the only known clue to a cyclone path is got froai a 

 knowledge of the movements of isobaric lines. In this instance 

 the rain in London was, I think, correctly forecast, but unfor- 

 tunately such a simple case rarely occurs in this country. 



Thus we see that a knowledge of the amount of moisture in any 

 current is of only secondary importance to synoptic forecasting, 

 so that if we may welcome the rainband as an addition to our 

 old stock of prognostics, there is little ground for hoping that it 

 will be of further service than them. 



All that Prof. Smyth claims for the spectroscope is to act as a 

 gauge of pure vapour quantity, but it eems probable that its 

 employment may be still further extended. There are strong 

 groun is for believing that an air spectrum may vary not only 

 with the amount of pure vapour, but also with the size, aggrega- 

 tion, and physical condition of the condensed vapour suspended 

 in it. For instance, take the so-called rain lines. These may 

 appear either alone, or with a rain-band of any intensity ; so that 

 if the band is due to pure vapour only, the lines uiu-t depend on 

 some other condition Again in sunset tints we have a natural 

 spectroscope whose colours certainly are the product of both the 

 quantity and quality of the total moisture suspended in the air. 

 I have made a large number of observations on the lurid, 

 coppery, yellow, green, and red skies, which form such a large 

 portion of all weather lore, but without decisive results ; for sun- 

 set spectra arc too complicated and too fleeting to be unravelled 

 by a small instrument. They certainly seem to differ, but their 

 spectra are not so marked as their appearance to the naked eye. 



But even supposing that this idea is completely verified, and 

 that the spectroscope can be used as a new weapon of research 

 to discover the still unknown nature of clouds, and that we are 

 ever able to say that Mich and such an absorption spectrum belongs 

 to such and such a kind of sky, there are no grounds for believ- 

 ing that we can ever regard these spectra otherwise than as a new- 

 set of sky prognostics, or tbat as such they will be of more use 

 in forecasting than those already known. 



What the use of any prognostics is in forecasting, and how 

 they are related to synoptic charts, and how L-obaric lines map 

 out the shape of rain areas, are other sides of the great problem 

 of weather forecasting, which cannot be discussed here. 



Some may differ from Prof. Smythe as to the forecasting value 

 of the rain-band, but all will appreciate the singular skill with 

 which he has surmounted the practical difficulties in the way of 

 making it a quantitative measure of atmospheric vapour. 



21, Chapel Street, S.W. October 2 Ralph Aberckomby 



The Comet 



When observing the comet this morning, with 74 inch 

 aperture and powers of 70 and 150, I at once noticed that the 

 nucleus was far from circular, the length being carefully esti- 

 mated at 45" and the breadth at 15, while the measured 

 "Position" of the maj. axis was (96°-276°) ; this was also the 

 supposed direction of the tail, which had ceased to be visible in 

 the increasing twilight. 



At 6h. om. G.M.T. the place of the comet was 

 R.A. = ioh. 27m. 3 ± 5 sees. 

 N.P.D. = ioo° 36' 30" ± 10". 

 These places, taken with the equatorial, were confirmed by 

 measures of the not far distant star a Leonis. They differ con- 

 siderably from the calculated pace given in the Dunecht Circular, 

 No. 60. Wentworth Erck 



Sherrington House, Bray, Co. Wick low, October 9 



" Note on the History of Optical Glass'' 

 The writer of the article in a recent number of your journal, 

 entitled "Note on the History of Optics! Glass," has fallen into 

 some historical blunders and anachronisms, which are the ground 

 of my addressing you. My grandfather was born in 173S, and 

 would therefore have been but twenty years of age at the date 

 when he is said to have made the acquaintance of the elder 

 Guinand, then sixteen, in Switzerland. It is almost certain that 

 he never was there, at any rate not as an "illustrious savant," 

 engaged in telescopic experiments. His sister's memoirs present 



a blank at this exact date, but it is evident that if he travelled it 

 the time when he withdrew from the Hanoverian military service, 

 it was in the character of an obscure young musician. It is ju-t 

 barely possible that there may be some foundation for the story 

 now given— and if so, I should be glad to learn it— but a totally 

 mistaken colour has been given to it by drawing on the fu ure. 

 What follows is still more erroneous. Dollond (the elder) was 

 at this period at the zenith of his fame as an optician ; 

 was not born, and Herschel was an ex-bandsman; jet we 

 are told that he " returned the following year with Lollond 

 and Faraday." It is probably something more than a mere 

 coincidence that about sixty years later the son of that 

 Herschel, the son of that Dollond, and Faraday, were as-o- 

 ciated in treating with the son of that Guinand fur the 

 glasses manufactured by the latter. Apart from this, I submit 

 that hardly anything new is contributed in the "Note." AH, 

 and more than all, which it contains will be found in the 

 Biographic Universellt, under the name Guinand, where also 

 is mentioned the Suiss rencontre, but with the name Die: in 

 lieu of "Herschel and Utzchneider." According to the 

 Biographic, Guinand was born "about 1745," and died in 1825. 

 It was in if>2i that the Astronomical Society was instigated to 

 make inquiries (conducted by my father) regarding Gumand's 

 optical glasses. j. Herschel 



A "Natural" Experiment in Complementary Colours 

 About two miles above Ormeim. in the Romsdal (Norwaj) is 

 the well-known Slettafos, an imposing cascade formed by the 

 impetuous Rauma, which here 1 lunges through a deep locky 

 ravine. Fascinated by the scene, I stood watching the foan ing 

 water for some time, and all at once noticed a most beautiful 

 and delicate rosy pink tint colouring the foam and spray in the 

 ravine. The w ater, where not broken up, was of a green colour, 

 and the pink tint was at ence explained as its complementary. 

 But the point of special interest to n-e was that this pink colour 

 was not visible except on those parts of the spray and foam 

 which were in the sshede of the gorge. In the full light these 

 appeared, as u.ua!, white. The result above described is an 

 excellent illustration, afforded by nature herself, of the advantage 

 of toning down the 1 tightness of the white surface, upon which 

 we w ish to evoke a c mj lementary tint, until it no longer exceeds 

 that of the exciting lolour — the green in this case. 



Chas. T. Whitmell 

 II. M. Inspector of Schools 

 9, Beech Grove, Harrogate, September 11 



Animal Intelligence 



In the article on animal intelligence [(Nature, vol. xxvi. p. 

 523), Mr. Morgan seems to me to have inverted the real 

 process in the case of what he calls "isolation," for he says: 

 " 1 believe such abstract ideas to be impossible for the brute. I 

 believe them to be the outcome of the use of language." The 

 process of abstraction here alluded to is the conception of a 

 quality apart from the things that possess that quality, as white- 

 ness or edibility. 



I watched a little child ju s t able to walk alone, on a railway 

 platform. It went up to a .- quare box, and after staring at it for 

 a few seconds, slowly passed its hand over the top, front and 

 sides, ai.d then along the edge, clearly testing the sen -e 

 by that of touch. It then did the same with the small wheel of 

 a luggage barrow. It was obviously too young to be able to 

 speak, but I think w e may safely assume that it got a notion of 

 what we call "square" and "round." Now a dog can readily 

 acquire a somewhat similar experience, by finding a barrel to be 

 less easy to stand upon than a square box. So far they are 

 much aiike; the child, however, certainly exhibited a greater 

 inquisitiveness than a dog is likely to do. 



It is obvious that a doj; can receive just the same impressions 

 as a child through the senses, so that automatic appreciation of 

 the difference between roundness and squareness is common to 

 bot_ ; bur, whereat, the dog, »a I believe with Mr. Morgan can 

 never get beyond that stage, a chdd, ifnot an infant, can make the 

 difference an object of thought or a mental abstraction, even without 

 having a word to express it ; just as an adult experiencing a new 

 but uncomfortable sensation, can think of it, and coin a term to 

 express it, say, "all-overishness;" or again, as one can feel 

 indignant or benevolent, ard at the same time think about such 

 states without necessarily giving expression to them. If words 

 were necessary, as Mr. Morgan seems to think, then a deaf- 



