462 



NA TV RE 



[March 14, 1895 



The Velocity of the Argentine Earthquake Pulsations 

 of October 27, 1894. 



In several recent notes in Nature (pp. 232, 371, 393), 

 attention has been drawn to the great Argentine earthquake of 

 last October 27, and to the record of its pulsations in Europe. 

 In one of these (p. 371) a rough estimate is given of the velocity, 

 but a more detailed one seems desirable on account of the great 

 Jistance traversed liy the pulsations. 



According to M. Nogute (Comfits rendiis, vol. cxx. pp. 

 167-170), the epicentral tract includes Rioja, San Juan and 

 Mendoza. There is thus some uncertainty as to the exact posi- 

 tion of the spot from which the pul>ations started. In the 

 following estimate I have supposed it to coincide with San 

 Juan. 



San Juan is about 312 km. from Santiago, and 11,600 km. 

 from Rome, the difference being li,2S8 km. The earthquake 

 was rcgistertd by a seismograph at Santiago at 8h. 50m. 26*. 

 p.m., Greenwich meantime. The slight preliminary pulsations 

 were recorded by the great seismomelrograph at Rome at gh. 

 7m. 35s., the first maximum at gh. 49m. 503., and the principal 

 maximum at gh. 55m. 40s. -Assuming that the first maximum 

 (or beginning of the larger pulsations) corresponds to the move- 

 ment which started the seismograph at Santiago, it follows that 

 the distance of 11,288 km. was traversed by the pulsations with 

 an average velocity of 317 km. per second. 



It should be remarked that this estimate agrees very closely 

 with those ohtained for 'he same phase of the movement in the 

 cases of the Greek earthquake of April 27, and the Consianti- 

 nople earthquake of July 10, 1894 (namely, 321 and3'2okm. 

 per sec. respectively). 



For the first slight movements recorded at Rome, Charkow 

 and Nicolaiew, we must admit either that the pulsations 

 producing them started some time before the great earthquake, 

 or else that they travelled with a far higher velocity. If they 

 left San Juan simultaneously with the larger pulsations (i.i. .it 

 8h. 48m. 48s.), their average velocity must have been 

 io"j8 km. per second. The horizontal pendulums at Charkow 

 and Nicolaiew also recorded these early movements, beginning 

 at gh. 8m. 36s. and gh. 12m. 6s. respectively ; soon after 

 which the curves more or less completely disappeared. San 

 Juan is about 13,625 km. from Charkow and 13,240 km. from 

 Nicolaiew, the average velocities to these places being therefore 

 1 1 47 and 9 47 km. per second. The latter obviously corre- 

 sponds tu a later phase of the movement. 



Whether the slight preliminary pulsations start before, or at 

 the momerit of, the earthquake, is a question of the greatest 

 practical importance from the point of view of earthquake- 

 warnings. To aODwer it, one ol the Italian seismometrographs 

 or a h'jrizontal or bifilar pendulum should be placed beside a 

 seismograph in the immediate neighbourhood of the centre of 

 disturbance. C. Davison. 



Birmingham, March 6. 



The Society of Spelaeology. 



The attention of jour readers has already been called to the 

 format on of this Society in Paris (Nature, January 3), the 

 promotion < f which is due to the action and enthusiasm of 

 .M. E. A. Martel, the author of the beautifully illustrated work 

 " Les Abimes," reviewed by Prof. Bonney in )our pages of the 

 28th ult. This book describes and illustrates a number of 

 extraordinary and often hazardous subterranean explorations in 

 the undergr .und caves .ind watercourses ol the limestone 

 districts of France, lie'gium, Auilna, and Greece. The 

 Society is intended to cirry on the work thus initiated by 

 M. Martel and his devoted co workeis in a more effective 

 manner, and over a wider area than has been possible by 

 private enierpri.«e. The formation of the Society, M. Mattel 

 writes me, is nf.w an accomplithed fact. About 130 gentlemen 

 of all nationalities, fome of whom bear well-known names in 

 the ranks of science, have signified their aiihesion. A pro- 

 visional code of rules has been printed and adopted, and a 

 meeting has already taken place, under the presidency of the 

 presidtnt-elect, M. F. Deloncle, Ileputy for the Uasses-Alpcs. 



The first article of the rules slates the object of the Society as 

 follows: — "The Society of Sprlaeology is instituted in order to 

 ensure the exploration— to facilitate the general study— toco- 

 operate in the regulation or ullilisation — of subterranean 

 cavities of all sorts, known or unknown, whether natural or 



NO. 1324, VOL. 51] 



artificial ; to encourage and aid with funds investigations relat- 

 ing thereto ; in a word to popularise and develop in a way, at 

 once practical and theoretical, utilitarian and scientific, re- 

 searches of all kinds in the interior of the earth." The subscrip- 

 tion for ordinaiy members is fifteen francs per annum. It is 

 intended to publish a quarteily bulletin ; to a copy of which 

 each member will be entitled. 



In order to fully carry out the objects of the Society, the pro- 

 gramme of which is a comprehensive one, more members are 

 required, and I sliall be glad to furnish any of your readers who 

 may wish to join the society with the proposal form or liulhtiit 

 (f Adhesion, or they may be olitained from M. Martel, General 

 Secretary, S Rue Mcnars, Paris. 



M. Martel, I may say, is desirous of extending his investiga- 

 tions to the British Isles, if sufficient inducement be offered in 

 the exploration of some large cave, as yet unworked or imper- 

 fectly known, and where his apparatus of rope ladders, collap- 

 sible boats, ic, would be useful aids. Information on this head 

 will be thankfully received by me. Mark Stirrui'. 



Bowdon, near Manchester, March 6. 



Contraction of Trees caused by Cold. 



The splitting of forest trees by frost is often ascribed to the 

 same cause which bursts a pipe charged with water when the 

 temperature tails below 32° F., namely, the expansion of the 

 water on turning into ice. Botanists know that this is not so, 

 but the splitting is owing to a contraction of the wood by frost, 

 similar, but in a less degree, to what happens when the wood 

 is dried. With the thaw the trees expand to their original 

 dimensions. Evidence of such contractions and expansions is 

 furnished by the measurements herewith. 



For some years past, I have regularly taken the girths of a 

 number of forest trees during summer, in order to note the 

 amount of growth. To do this accurately I have to use a steel 

 tape, and of course to girth the trees at exactly the same place. 

 My experience, thus acquired in measuring to a nicety, is a 

 sufficient reason for confidence that the following figures are 

 substantially correct. 



Girth of trees in 



Octol>er 1894, when done 



growing and before the 



frost. 



Girths, 



February 8, 

 1895, 9 a^.m. 

 Temp. 3* F. 



j Girths, March | Amount of 



' 3, 189s, 3 p.m. I contraction 



Temp. 39 F. , with frost. 



Bradford, March 4. 



J. Clayton. 



The Barrenness of Precambrian Rocks. 



Referring to the paragraph in Natukk (February 2S, p. 423), 

 on the sudden a])pearance of a rich fauna in the Lower Cambrian 

 rocks, I should like to make a suggestion for the consideration 

 of geologists. May not the extreme poverty of organic remains 

 in Precambrian (Arch.x-an) strata be largely due to a scarcity of 

 carbonate of lime in the water of the Precambrian seas? The 

 Uriconian and Longmyndian rocks of Shropshire, which, at 

 the very lea^l, must include five miles of sediment, comprise 

 hardly a scrap of limestone. The same remaik will apply to 

 the Precambrian strata of Charnwood, South Wales, the main- 

 land of North Wales, and the great Torridonian group of 

 .Scotland. The Pebidian rocks of Anglesey contain liands of 

 limestone, it is true, but it in highly probable that they arc of 

 chemical origin, and not derived from oceanic waters. There 

 are, of course, plenty of limestones in the older .'\rch:ean rock* 

 of North .\merica, and a few of ihcm in the Lower Archa:ans ol 



