l62 



NATURE 



{Dec. 28, 1 87 1 



science that might not be " briefly refuted " by such a method ' 

 but I think it would be fair to employ the words, " particular 

 opinions of Sir VV. Thomson" in place of "principles of natural 

 philosophy,'' and "imaginary consequences of these 0])inions " 

 in place of "facts." If^his were done, all woidd admit that Sir 

 \V. Thomson's arguments are conclusive demonstrations ; grant od 

 the premisses, the conclusions certainly follow. Hut geologists have 

 simply to assume the contrary premisses, and they may niatlie- 

 matically demonstrate the reverse. Agree to beg all the diffi- 

 culties of a question, and a certain conclusion may easdy be 

 obtained. This fact was recognised in the Middle Ages, and 

 Mayer has not got rid of it. 



P. W. Stuart Menteath 

 42, Rankeillor Street, Edinburgh 



[The remarlis of Prof. Tait are contained in his opening 

 lecture for Session 1869-70, which was sent to us with permission 

 to make what use of it we chose. As the matter of Geological 

 Time had been very fully discussed in this countiy, we did not 

 insert the portions bearing on it. We believe that the portion 

 which we did insert induced the editor of the Rtiutc to apply to 

 the author for the whole MS. As to tlie queries in the above 

 letter we may note, 



1. The Dissipation of Energy is a necessary consequence of 

 the second law of Thermodynamics. 



2. If " Mayer categorically denies its universality," so much 

 the worse for his own credit, and for that of " the Frencli 

 Academy and the eminent English and German savants " who 

 sujiport him. 



!- 3. It is not for us to say what Sir W. Thomson would, or 

 co^ild not, do. 



4. So, after all, Mayer seems to be no better than Sir \V. 

 Thomson.— Ed.] 



In Re Fungi 



It may allay the alarm of your correspondent " W. G. S." 

 as to the decay of fungology in England, as far, at least, as one 

 of the cases wliich he tiuotes is concerned, to be informed that 

 so careful and critical a student of fungi as Mr. W. G. Smith con- 

 firmed the determination referred to, and on the faith of the 

 abnormal specimen, included this rave and very critical species 

 without any hesitation among the Jiliddlesex'fungi in the "Middle- 

 sex Flora," p. 40S. Your correspondent " W. G. S." has missed 

 the point of the paragraph from the Jinirital of Botany which he 

 criticises. The specimens of this fungus collecied by Mr. 

 Wooster at Whitehall Gardens have a regular and normally deve- 

 loped pilcuf, and were in striking contiast to the "abnorm.al 

 specimens" (W. G. Smith, /. c ) from the Goswell Road. 



A Shadow on the Sky 



I no not know how common is the phenomenon described by 

 Mrs. Charlotte Hall in N.vruRE of Nov. 9 (p. 25), but her com- 

 munication leads me to report a much less striking appearance 

 of the same kind, which I witnessed Feb. 20, 1S70, in this 

 nei'dibourhood. I was taking an early walk, and had mounted 

 to the top of a ridge commanding an eastern view, about fifteen 

 minutes after sunrise. The sky was veiled in a dark white. 

 Above me, a little to the south and east, hung a ball of vapour 

 in mid- air, warmed into smoke-colour by the rays of the sun, 

 and yet so dense as to cut off these r.ays, and cast a rectilinear 

 shadow of dark blue against the while coat of the sky. The 

 shadow was sharply defined, and the whole effect was not unhke 

 the nucleus and tail of a comet. In a few moments the shadow 

 faded out, and, shortly after, the ball itself was dispersevl. The 

 moon in its third quarter, was visible somewhat past the zenith, 

 and surrounded with vapour. Twelve hours later we had a 

 violent rainstorm. N. J. 



New York 



Coal Measures of Ireland 

 In the new edition of Jukes's " Manual of Geology," by Prof. 

 Geikie, at page 592, it is stated, on the authority of Kir. E. Hull, 

 that '"in Leitrim, Fermanagh, and Tyrone, there are true repre- 

 sentatives of the Yoredale series of England." I, however (as 

 also the late Mr. Jukes), contend that no comparison can be 

 drawn between the coal bearing rocks of Ireland and those of 

 England. Furthermore, as Mr. Hull is unacquainted with these 



Irish rocks, having only seen a few isolated patches of them, I 

 protest against his being quoted as an authority on the question, 

 more especially as in the paper to which Mr. Geikie referred, 

 "On the Geology of the Ballycastle Coal Fields, &c.," Mr. Hull 

 states that while in the counties al)ove mentioned there are true 

 coal measures, in the provinces of Leinster and Munster there 

 are none — a statement quite contrary to fact-", as all the sections 

 of these rocks in Leinster, Munster, and Connanght are identical, 

 and probably, as suggested by the late Mr. Jukes, were once con- 

 nected, as the lowest bed of coal occurs everywhere at a nearly 

 equal height above the limestone. Furthermore, the intervening 

 strata are nearly identical, there being a certain thickness of 

 argillaceous beds below, next the limestone, and a mixture of 

 arenaceous and argillaceous beds above. 



Naturally it may be expected in all places where a sea 

 gradually became shallow, that limestone would be succeeded 

 by fine argillaceous beds, the latter by shore beds, more or less 

 coarse and arenaceous, and eventually by land beds, such as 

 coal, fire-clay, clunch, and the like. 



Similar sequences are not uncommon, both on a large and 

 small scale. On the large scale in the passage rocks from the 

 limestone to the coal-bearing rocks of most countries, and on a 

 small scale in the north of Ireland and in Scotland, where a bed 

 of limestone will be succeeded by a shale, the shale by a sand- 

 stone, and the latter by a clay or coal. 



If we examine into the thickness of the English and Irish 

 rocks, the difficulty of a comparison is apparent. In the latter 

 country the greatest thickness of the rocks called coal measures 

 never exceeds 3, 500 feet, this series of strata including all the 

 rocks above the limestone ; whilst in Lancashire, according to 

 Mr. Hull's sections, the Yoredale beds alone exceed 5,000 feet in 

 thickness. 



Moreover, if any value is to be attached to palceontological 

 evidence, we find that from the base upwards in the Irish 

 rocks there are fossils which in England are considered to be 

 characteristic of the true coal measures. The latter fact would 

 seem to suggest that while in Ireland the upper part of the 

 limestone was being deposited, in England the millstone grits 

 and Yoredale rocks were accumulating, whilst subsequently, in 

 both countries, true coal measures were deposited ; those in 

 Ireland being unfortunately very poor in coal, although con- 

 taining very similar fossils. 



In the northern extremity of Ireland, and in Scotland, the 

 measures are very similar, and in certain places apparently 

 identical, as pointed out years since by Sir R. Griffith. This, 

 therefore, is no new fact, as Messrs. Hull and Geikie would sug- 

 gest to their readers. G. Henry Kinaiian 



Recent Changes in Circumpolar Lands 



Some years ago I wrote a paper for the Ethnological Society 

 on some changes of surface affecting Ancient Ethnography. 

 Since this was printed many facts have accumulated. Tliese 

 have led me to a tentative generalisation on the subject, which I 

 should like to have discussed in your pages. 



The question of the upheaval and subsidence of different areas 

 of the earth's surface, as it is going on at the present moment, is 

 of very great importance in geology, and yet few subjects have 

 been more neglected. A few facts have been here and there 

 collected ; but even the best authorities treat the matter in a 

 jejune fashion. According to them the areas of upheaval and 

 subsidence are scattered over the earth's surface in an irregular 

 manner, without any definite law or rule. I believe that with 

 very slight local exceptions there is a very distinct law which 

 governs the subject. 



Putting aside altogether the southern hemisphere for the 

 present, I wish to prove that the area of upheaval is confined to 

 the land bordering the Polar Sea, and to the Polar Sea itself ; 

 that it is perfectly continuous all round the earth, and that it is 

 greatest near tlie Pole, and gradually diminishes until it disap- 

 pears about the 57th parallel, leading to the conclusion that the 

 focus of upheaval is the Pole itself. 



Of course, my observations are entirely confined to what is 

 taking place now, and are not to be confused with the facts of 

 any otlier period, historical or geological. 



Commencing with Scandinavia, we have the remarkable testi- 

 mony of Pliny, Mela, Solinus, and others, to the fact that Scan- 

 dinavia was considered by the Roman geographers, whose 

 authorities were bold and expert seamen, to be an archipelago. 

 Ptolemy speaks of the Scanctian Islands. The very name Scan- 

 dinavia is evidence that those who iwed it looked upon it as an 



