March lo, i8Si] 



NA TURE 



43: 



Memoires de la Socictc des Sciences I'hydques et Natur- 



dies dc Bordeaux, i" s^rie, tome iv., I™' cahier. 



(Paris: Gauthier-Villars, iSSo.) 

 THiSnumbercontains Conferences deGeomdtrie sup^rieure 

 by M . Saltel, in which is given an exposition of the method 

 of analytical correspondence with two applications, the 

 object of the one being to find the number of common 

 solutions in /■ equations between k unknovyns, and of 

 the other to find the degree of a geometrical locus defined 

 by certain algebraic conditions. The methods employed 

 are based on that of M. Chasles's "Principe de Corre- 

 spondance." The next paper, by M. Imchenetsky, " De- 

 termination en fonction des coordonncfes de la force qui 

 fait mouvoir un point materiel sur une section conique," 

 is an interesting one, and is founded upon a remark of 

 M. Bertrand's ("Sur la possibility de ddduire d'une seule 

 des lois de Kepler, le principe de I'attraction, Coiiiptes 

 rendiis, April 2, 1877), " il serait intdressant de rt^soudre 

 la question suivante. En sachant que les plan^tes d^- 

 crivent des sections coniques, et sans rien supposer de 

 plus, trouver I'expression des composantes de la force qui 

 les soUicite en fonction des coordonn&s de son point 

 d'application." The author arrives at his result by 

 taking his equation in the form — 



px'- -{■ qyr -f 3 rxy = {ax -\- by ■\- cf. 



Prof, Teixeira of Coimbra has a short note "Sur les 

 principes du calcul infinitesimal," which calls for no 

 special comment. Dr. G. Sous follows with what appears 

 to us a good article entitled " Phakomitre et C^ptomitre." 

 For the uninitiated " Les phakomfetres sont des instru- 

 ments destines k mdsurer la distance focale d'une lentelle 

 quelconque." The principle of construction of Silber- 

 mann's and of Snellen's is, when an object is placed at 

 twice the focal distance from a converging lens, the real 

 image of the same size as the object is situated also at 

 double the focal distance from the lens. The objection 

 to Silbermann's appears to be its length, which renders 

 it awkward to carry, and to Snellen's that it is not appli- 

 cable to diverging lenses. 



Dr. Sous gives a form which is not liable to either of 

 these defects, and the construction of which is based 

 upon a physical theory, not hitherto, he states, applied 

 to these instruments ; but we must refer those interested 

 in optics to the paper itself (fourteen pages in length). 

 The rest of the book is devoted to " Morphologie de la 

 membrane de Schrapnell," Dr. Coyne ; " Iitudes d'Optique 

 Physiologique ; Influence du Diametre de la Pupille et des 

 Cercles de Diffusion sur I'acuite visuelle," Dr. Badal ; 

 " Les Temperatures de la Mer dans I'estuaire Girondin et 

 a Arcachon en decembre, 1879, et Janvier, 18S0," M. 

 Hautreux ; " Des C's et de leur Emploi dans la Fabrication 

 du noir Animal, du Suif, du Sulfate d'ammonique, des 

 Boutons," &c., M. Huyard. 



LETTERS TO THE EDITOR 

 [ The Editor does not hold himself responsible for opinions expressed 

 by his corresfondtnts. Neither can he undertake to return, or 

 to correspond with the writers of, rejected manuscripts. No 

 notice is taken of anonymous communications. 

 The Editor urgently requests correspondents to keep their letters as 

 short as possible. The pressure on his space is so great thai it 

 is impossible otherwise to ensure the appearance even of com- 

 munications containing interesting; and novel facts, '\ 



Aberration of Instinct 



Cases of individual variations of instinct are of importance in 

 relation to Mr. Darwin's theory of the development of instincts 

 by natural selection. Under the belief that aberration of instinct 

 may be regarded as a case, more or less extreme, of variation, I 

 think that the following instance is worth publishing in Nature. 

 It has been communicated to me by a correspondent on whose 

 trui-tworthiness I have reason to rely : — 



"A white fantail pigeon lived with his family in a pigeon- 

 house in our stable yard. He and his wife had been brought 



originally from Sussex, and had lived, respected ar.d admired, to 

 see their children of the third generation, when he suddenly 

 became the victim of the infatuation I am about 'o describe. . . . 

 "No eccentricity whatever was remarked in ':is conduct until 

 on3 day I chanced to pick up somewhere in the 'garden a ginger- 

 beer bottle of the ordinary brown stone description. I flung it 

 into the yard, where it fell immediately below the pigeon house. 

 That instant down flew paterfamilias, and to my no small 

 astonishnient commenced a series of genuflexions, evidently doing 

 homage to the bottle. He strutted round and round it, bowing 

 and scrapin;,' and cooing and performing the most ludicrous antics 

 I ever behfld on the part of an enamoured pigeon. . . . Nor did 

 he cease these perf rmances until we removed the bottle ; what 

 proved that this singular aberration of instinct had become a fixed 

 delusion was this, whenever the bottle was thrown or placed in 

 the yard — no matter whether it lay horizontally or was placed up- 

 right — the ^ame ridiculous scene was enacted ; at that moment the 

 pigeon c.ime flying down with quite as great alacrity as when his 

 peas were thrown out for his dinner, to continue his antics as 

 long as the bottle remained there. Sometimes this would go on 

 for hours, the other members of his family treating his move- 

 ments with the most contemptuous indifference, and taking no 

 notice whatever of the bottle. At last it became the regular 

 amusement with which we entertained our visitors, to see this 

 erratic pigeon making love to the interesting object of his affec- 

 tions, and it was an entertainment which never failed, throughout 

 that summer at least. Before next summer came round he was 

 no more." George J. Romanes 



Prehistoric Europe 

 A FEW last words with Prof. Dawldns, and I have done: — 



1. Having discovered that a certain absurd opinion which he 

 attribut'd to me is nowhere to be met with in the volmne he was 

 suppo-e 1 to be criticising, Mr. Dawkins now imagines that he 

 has found grounds for his assertion in my "Great Ice Age," 

 written and published some ye" rs ago. Here again he is quite 

 mistaken. The passage cited by him, even if it be considered 

 apart from its context, will not bear the interpretation he puts 

 upon it. Had he read the page he quotes from with intelligent 

 attention he would have seen that I was referring to the v ell- 

 known fact that the os.'iferous and Palaeolithic gravels of East 

 Anglia are represented in the North by the equivalent ossiferous 

 Cy;T«fl-l'eds near Hull, which dovetail with and are overlapped 

 by glacial deposits. In other words, they rest upon a lower, and 

 are covered by an upper boulder-clay. But I have nowhere said, 

 nor would any candid reader infer from v\hat I have written, 

 that this upper boulder-clay (that of Ilessle) ever extended south 

 so as to cover the Palaeolithic gravels throughout East Anglia. 

 I am surprised that a professor of geology does not apparently 

 understand the meaning of the term "overlap." Were I to 

 state that in certain districts in Scotland the Carboniferous strata 

 are overlapped by a conformable series of Red Sandstones, should 

 I be understood to imply that these Red Sandstones formerly 

 covered the entire area now occupied by the Carboniferous rocks 

 of Great Britain? 



2. Mr. Dawkins has accused me of having suppressed evidence 

 which t'ld against my views, and he now repeats this offensive 

 accusation, citing in justification my description of the Victoria 

 Cave, from which, he says, I have omitted all reference to the 

 discovery of reindeer in the lower cave-earth. Now it is not 

 true that I liave ignored this alleged discovery, for I remark 

 that "it seems doubtful whether the remains of that animal, said 

 to have been obtained from the lower earth, really belonged to 

 that deposit." My reasons for this doubt (which I share with 

 other geologists) I did not consider it necessary to give, but they 

 are simply these : — 



(1) The explorations in the cave were carried on at first, under 

 Mr. Dawkins's superintendence, by means of shaft-digging, a 

 very unsatisfactory system of "cave-hunting," and one which, 

 even with the most conscientious care, is liable to give false 

 results. 



(2) During the subsequent prolonged and scientifically-con- 

 ducted explorations no recognisable reindeer remains were ever 

 obtained in the lower stratum. These facts alone are sufficient 

 to justify my scepticism. I quite agree with Mr. Dawkins, 

 however, that the mere occurrence or non-occurrence in this 

 particular cave of reindrer associated with hippopotamus i^ not 

 of paramount importance. Even the most inattentive reader of 

 "Prehistoric Europe " can hardly mi!S the statement, again and 

 again repeated, that the southern and northern forms are often 



