Sept. 27, 1883] 



NA TURE 



5i5 



on the subject, and am anxious to state one or two matters which 

 I learned from him concerning questions raised in my review. 

 Prof. Marsh has visited Brussels since I was there, and since M. 

 Dollo's memoirs referred to by me were in print, and has 

 examined the Iguanodon skeletons with M. Dollo, this being the 

 second occasion on which he has seen the collection. After 

 having examined the specimens now available he is of opinion 

 that the question whether the bones considered by M. Dollo to 

 be sternal are in reality such, or clavicles, is still an open one. 

 The form of the bones, which are undoubtedly identical with 

 those in the British Museum specimen determined by Prof. Marsh 

 to be clavicles, is exactly that of clavicles and unlike that of any 

 known sternal bones. There can be no doubt that they belong 

 to the pectoral arch, but the position in which they have been 

 found in two Bernissart specimens points to their belonging 

 rather behind than in front of the coracoids. It is, however, 

 Prof. Marsh believes, just possible that they may have fallen 

 forward into the position in which they there occur, and he 

 awaits the results to be attained from their examination in the 

 ether Bernissart specimens before making up his mind. In the 

 closely-allied Hypsilophodon the sternum is a single broad- 

 keeled plate. In the case of the British Museum specimen one 

 of the bones is attached to the scapula. At all events, he points 

 out that, should these bones really prove to be sternal, it does not 

 follow that Iguanodon had no clavicles at all, for there is a 

 process on the scapula indicating the presence of a clavicle, and 

 such a bone, possibly very small and rudimentary, may yet be 

 found to exist. 



The statement of Prof. Marsh that the post-pubis in Iguanodon 

 U long and slender, and incomplete, is correct ; the conclusion 

 that it was not so arose from a misunderstanding of the exact 

 meaning of the term incomplete, as used. It denotes that in 

 Iguanodon the bone does not extend, as it does in some Dinosauria 

 (Hypsilophodon), I ackvvards as far as the ischia, or farther, as in 

 Mime birds, and this, as will be seen by reference to the figure is 

 the case in Iguanodon, in which the post-pubis does not extend 

 much further back than just beyond the ischial tuberosity. The 

 i act is proved clearly by British specimens as well as by those of 

 Bernissart. Prof. Marsh has observed that in two or three of the 

 Bernissart skulls sutures are distinctly to be seen. 



H. N. MOSELEY 



Prof. Henrici's Address at Southport 



Though a member of many years' standing of the British 

 Association, 1 have not had the advantage of being present at 

 the current meeting, and am altogether indebted to the report in 

 Nature for a knowledge of Prof. Henrici's opening address in 

 Section A. 



It is much to our advantage to have our educational deficiencies 

 in certain points indicated to us in so candid and, at the same 

 time, so kindly a manner as Prof. Henrici has done on this 

 recent as well as on former occasions ; and I hope we shall 

 profit by such friendly criticism. Had I been present, however, 

 I should have ventured to remark on two heads of the address, 

 that I thought Prof. Henrici underrated (1) the extent to which 

 the modern geometry has been cultivated in these countries by 

 many who have not been fettered by the "slavery of examina- 

 tions" (an expression in which I entirely sympathise), chiefly 

 under the influence of the great geometer Chasles' works ; (2) 

 the character of the instruction our youth receive in decimal 

 arithmetic, the abbreviated methods of processes in which being 

 certainly found in our better class of text-books, notably in that 

 of the late Prof, de Morgan, dating back some fifty years, may 

 be assumed to be taught generally in our higher-grade schools, 

 as I certainly know to be the case in several. Other remarks, 

 turning rather on matters of opinion than of fact, which occur to 

 me, would be considered, probably, out of place here. 



J. J. Walker 



Scientific Aspects of the Java Catastrophe 



Your excellent leading article on this great event omits to 

 call attention to a factor which I have long maintained to be of 

 the greatest interest and importance from the point of view of 

 meteorology and geology in general. I allude to the quantity 

 of gases or vapour emitted during the eruptions. This must 

 bear a direct relation to the quantity of matter emitted (what- 

 ever its form) and also to the height and distance to which 

 the matter may be ejected or carried. 



Now I hold that such vast quantities of gases as must have 



been liberated on this occasion cannot be passed over or taken 

 as having no action on our atmosphere. Whatever the addition 

 made, temperature and currents are influenced by it either locally 

 or over great extents of the earth's surface, and if it were 

 possible to take account of the height attained by the gases, 

 their temperature of liberation, and the point of the surface of 

 the globe whence proceeding, some judgment might be at- 

 tempted of their action. In the present state of meteorology 

 we know nothing of these quantities, but it is justifiable to 

 assume that the upper currents of the air may be thus profoundly 

 influenced, and that in certain rases cyclones may thus be 

 generated. The present very fine dry weather we are enjoying 

 here, with the high and steady baronn'ter, may be a result of the 

 great eruption, and it will be worth while to note if any ab- 

 normal conditions of atmosphere be found to prevail during the 

 coming months. J. P. O'REILLY 



Dublin, September 16 



"Elevation and Subsidence" 



Mr. Young appears to think that I hold the view that rocky 

 matter will melt at a lower temperature when under greater 

 pressure. I did not intend, in my letter of August 24th, to ex- 

 press such an opinion as my own, but only to say that this was 

 not a settled question ; quoting the experiments upon which the 

 doubt was founded. 



Again, I merely mentioned the hypothesis that the matter of the 

 nucleus may be above its own critical temperature as "con- 

 ceivable." To all Mr. Young's present queries I should be 

 disposed to answer in the affirmative, except to the second — "Do 

 not the 'rigidity ' calculations incontestably show that the earth 

 is extremely rigid, i.e. solid ? " Asa geologist I do not concern 

 myself anxiously about the nucleus. But to hold that the super- 

 ficial parts are rigid I assert to be absolutely contrary to the 

 known facts of geology. Perhaps it will be said that they ought 

 to be, and therefore so much the w orse for the facts. 



Again, I say that mere plasticity of the upper layers will not 

 explain the phenomena. The arrangement of rocks in the in- 

 terior of mountain chains shows that the crust has been pushed 

 over the surface towards them. It must, therefore, rest on a 

 lubricating substratum. Again, mountains tend to rise and sedi- 

 mental plains to sink. If mere plasticity were all, the reverse 

 would happen. 



As I understand it, the tidal argument for rigidity amounts to 

 this. If the earth were not rigid, the fortnightly tide would be in- 

 appreciable. But Prof. Darwin, after most laborious and involved 

 reductions of observations made at the instance of the Iudian 

 Government, has come to the conclusion that such a tide can be 

 detected— not of its full amount, however (so far negativing 

 absolute rigidity), but something less than three-quarters of that. 

 The undiminished amount ought to be 4J inches only. The barriers 

 caused by my "roots of the mountains," which, as noticed by 

 Mr. Gardner, would break up the continuity of the substratum, 

 would, as I have elsewhere pointed out, be great obstacles to the 

 formation of tides in it. O. Fisher 



Harlton, Cambridge, September 20 



A Complete Solar Rainbow 



Although I quoted Capt. Winchester's figures as to the 

 diameter of the circumsolar bow, mentioned in my letter on 

 p. 436, I may add that this measurement was checked by that 

 of the chief officer (Mr. Grant), who took the distances from the 

 horizon to the inner rim of the bow on both sides, and subtracted 

 them from 180°. In the case of the Captain's measurements, in 

 the first instance, he measured from the inner rim of the bow to 

 the edge of the sun. This was doubled, and the diameter of the 

 sun added to it. Under these circumstances I can hardly believe 

 there could have arisen the mistake suggested by Dr. Ingleby. 



September 17 D. Morris 



C. M. Ingleby (p. 489) is clearly mistaken in supposing 

 that D. Morris's description in Nature (p. 436) referred to a 

 real rainbow, for he makes no mention of any rain, the pheno- 

 menon being on a thin film over the sky. It must have been a 

 solar halo, differing from an ordinary one only in being more 

 distinctly coloured than usual. I have on rare occasions seen 

 small portions of an ordinary halo very brilliantly coloured, but 

 never saw a complete one so. T. W. Backhouse 



Sunderland, September 24 



