October io, 1895J 



NA TURE 



569 



Colonel Basevi's criticisms of Clausius' virial theorem are 

 not justifiable. 



In the first place, the left-hand side of his equation at the foot 

 of p. 413 should be ux - [h-i]( , o. since the latter term is not 

 necessarily zero even for periodic motion ; e.g. it equals I if 

 v = exp. (sin t). 



In the next place, though this difference' obviously vanishes 

 for periodic motion when the "suitable value given to t" is a 

 multiple of the period, yet for this same value of / the areas 



/ uci.x and / .xdu will not vanish ; indeed for no value of / can 



the former vanish, as it represents / (dxjdtfdl, which is the sum 

 of essentially positive quantities. Hence we can have but 

 / tui.x = - I xdu when xit = [xit]. = q. 



Thirdly, though in the case of stationary motion the areas / tidx 



and — / xdu may not be exactly equal for any value of /, yet 



4heir difl'erence can only fluctuate within certain narrow limits, 

 so that when multiplied by 111I21 it becomes vanishingly small if 

 •/ is large enough, which is all that Clausius asserts. 



Fourthly, Clausius does not take m j udx to rep esent kinetic 



■energ}', but this expression divided by 2/. 



Fifthly, the fact is overlooked that R refers, not to single 

 particles, but to fiai'rs of particles ; so that in Lord Rayleigh's 

 case, JSRr = AR/", and not Kr, as asserted, there being only 

 one pair of particles in question, and the virial equation does 

 therefore give R = wz'-/p, the ordinary law of force for uniform 

 circular motion. 



Lastly, there is no ground whatever for taking 3\> and 42Rr 

 as equal terms, there being absolutely no connection between 

 them except that both represent energy ; indeed, by this assump- 

 tion Colonel Basevi obtains a formula w hich gives for the pressure 

 in an ideal gas only half its proper value. 



Christ Church, Oxford. Robert E. Bavnes. 



Mutton's "Theory of the Earth." 



It is to be doubted whether any work, with the exception of 

 LyelTs " Trinciples," has had a more important influence on the 

 science of geology than Hutton's "Theory of the Earth," in 

 which for the first time the true mode of studying the science 

 was set forth and its fundamental facts outlined. 



The theory w-as first iiropounded in a paper of some ninety- 

 five pages, written in 1705, which appeared in 1788 in the first 

 vohmie of the Transactions of the Royal Society of Edinburgh, 

 and was at once attacked by a number of hostile critics. 



Ten years later, in 1795, it was republished in Edinburgh, 

 greatly extended, and including the results of much additional 

 work, in two good-sized octavo volumes. These included the 

 substance of a number of papers published by Hutton after the 

 appearance of the first outline, ;is well as answers to his various 

 critics, and is the work \Vhich has become a classic in the science. 



The work, however, in its published form is evidently incom- 

 plete, for on the title-page it is stated to consist of four parts, 

 and, in the table of contents, volume i. is called part i. and 

 volume ii. part ii. Volume ii., furthermore, concludes abruptly 

 vith the following words : " Therefore in pursuing this object, 

 I am next to examine facts, with regard to the mineral part of the 

 theory. . . and endeavour to answer objections or solve difticulties 

 which may naturally occur from the consideration of particular 

 appearances.'' 



Parts iii. and iv., so far as I can ascertain, if written, were 

 never published. In the library of the (Jeological Society of 

 London, however, there is a manuscript of Hutton's which is 

 apparently a portion of one or other of these parts. It is bound 

 in book form, and was presented to the library by Leonhard 

 Horner, Esq., and in a note by that gentleman, presenting it to 

 the Society, it is stated to be one of a series, and to have been 

 given by Dr. Playfair, the populariser of Hutton's work, to 

 Lord Webb Seymour, and on the death of this nobleman to 

 have passed to the Duke of .Somerset, who gave it to Mr. 

 Horner. It bears no title, and consists of six chapters 

 •lumbered from iv. to ix. , and was evidently continued in 



NO. 1354, VOL. 52] 



another manuscript, as the last page, forming the conclusion of 

 chapter ix., bears the words " chapter x." at (he lower comer. 



The manuscript treats chiefly of a subject the investigation of 

 which has been so prolific of results in recent years, namely 

 granite contacts, and especially the contact of granite masses 

 with "schistus." He shows that the granite was not a 

 " primitive " rock on which the schist was deposited, but that it 

 was intruded through the latter in a molten condition, and holds 

 that it was the agent by which mountain-chains were upheaved, 

 sup|mrting his pro|X)sition by a description of the relations of 

 these rocks in various |)arts of .Scotland and elsewhere, among 

 them the Island of Arran. To the description of this last- 

 mentioned locality a whole chapter is devoted, in which the true 

 nature of the pitch-stones is also set forth, and the derivation of 

 the felsites from them by a process of dentrification is recognised. 



It is merely desired in the present letter to draw attention to 

 the fact that at least some other volumes of this manuscript are 

 extant, and to urge upon those who may know where they 

 might be sought, or who may by chance come ujwn them, the 

 importance of preserving them, and of placing them, if not in 

 the Ceological Society's library with the fragment above referred 

 to, at least in some library where they may be at once secure and 

 available for use. 



The book is one of the most remarkable which has appeared 

 in the history of geological science, and all who are interested in 

 the science must desire to see it secured and preserved in its 

 completed form. Fr.\.nk U. Ad.\ms. 



McGill University, Montreal. 



Abnormal Atlantic Waves. 



It happens that I have only quite lately seen a letter on this 

 subject in Natire of March 7, from Mr. E. C. Stromeyer of 

 Glasgow. It may perhaps be of interest to some of your 

 readers to learn that on January 6, 1891, and about 4 p.m., 

 the people of F'unchal, the chief town of Madeira, and situate 

 on the south coast (lat. 32° 37' 45" N., long. 16° 55' 20" W.) 

 were astonished by the arrival of a great wave which burst with 

 \tolence on the shore, coming seemingly from the S. E. or 

 E.S. F;. The sea had been calm previously, and the wind was 

 light. At Machico, a village some fifteen miles to the east of 

 Funchal, a similar phenomenon took place contemporaneously, 

 and also al Camara de Lobos, a village about six miles to the 

 west. At the latter place, where there is a small Uiy amongst 

 the rocks, there were three risings of the sea, one much higher 

 than the others. The bottom of the bay was laid bare, and 

 fishes were seen struggling in the mud. The boats lying on the 

 beach were more or less damaged, but I did not hear that other 

 property was injured. 



Two electric cables belonging to the Brazilian Submarine 

 Telegraph Company connect Funchal with Lisbon. Now, it is 

 worth noting that early on the morning .after the iKcurrence of 

 the great wave, when the Company's oflicials stationed at 

 Funchal went as usual to test the cables, one of Ihem was found 

 to be broken in deep water at a distance of seventeen or 

 eighteen miles to the .south of Madeira, whilst the other cable 

 w.as in good working order. It is an unsolved tjuestion whether 

 the same cause that produced the great wave had also broken 

 the cable, or whether the two events were simply coincident but 

 due to independent causes. 



Slight shocks of earthquake are felt at distant intervals at 

 Madeira, but no seismic disturbance was noticed near the date 

 of the great wave. 



-As the wave came from the southwards, I asked a friend to 

 make inquiry at Tenerife whether anything of the sort had been 

 experienced there. The reply was that nothing extraordinary 

 had occurred on January 6 at Santa Cruz on the south coast of 

 that island. At Puerto Orotava, on the north coa.st, there was 

 bright weather at the time, with light winds, and no wave had 

 occurred, nor had any earthquake been felt. 



James Vate Johnson. 



F'unchal, Madeira, September 17. 



Leaf-absorption. 



A i-EW weeks ago I threw some cuttings of the common 

 Privet (Ligiistnim vulgare) on the borders in the garden. Of 

 these cuttings some perished, while the remainder were drawn 

 into the soil by the worms, some with the cut end downwards, 

 some only by a single leaf, leaving all the rest of the cutting en 



