Dec. 9, 1886] 



NATURE 



141 



A great advance in our knowledge of typhoons in the Cliina 

 Sea will no doubt follow on the construction of a lighthouse 

 un the dangerous Pratas Shoal, such as has for many years 

 lieen talked about. Our storm- warnings would gain still more 

 in value, and the cost of construction need not exceed the loss 

 caused by a single disastrous typhoon. 



EARTHQUAKE IN SIERRA LEONE 



T'HE following correspondence has been forwarded for pub- 

 •*■ lication by Mr. R. II. Scott, F.R.S., Secretary, Meteoro- 

 logical Office : — 



Coz'eritmdit House, Sierra I.ione, October 2<), 1886 

 Sir, — I have the honour to transmit a copy of a communica- 

 tion received from Mr. J. M. Metzger, Manager of the Western 

 District, in which he reports that an earthquake was felt at 

 Sennehoo, in the Bompeh River, about the middle of last 

 month. 



(2) In the third and fourth paragraphs of his letter, Mr. 

 Metzger draws attention to the fact that the shock in question 

 was almost simultaneous with those experienced in other quar- 

 ters of the globe, and that the latitude of the Bompeh District 

 is within a few degrees of Charleston, America, where their 

 effects lately proved so disastrous. 



I have, &.C., 

 (Signed) J. S. Hay, 



Administratorin-Chief 



The Right Hon. Edward Stanhope, M.P., 

 &c., &c., &c. 



I H.WE the honour to state, for the information of His Ex- 

 cellency the Administrator-in-Chief, that on the return of the 

 District boat from the Bompeh River on the l6th inst., the cox- 

 swain reported that he had been informed at Sennehoo that 

 about the middle of last month an earthquake was felt at that 

 place and in the upper parts of the country ; in consequence of 

 which, many of the natives, who interpreted the event as prog- 

 nostic of coming war, hastened down to the water-side to pro- 

 cure arms and powder in preparation for hostilities, which they 

 regarded as imminent. 



(2) The shock is ^aid to have been continuous, accompanied 

 with a rumbling noise as of some heavy-laden cart being 

 moved along, resulting in the cracking and falling down of the 

 mud plaster on the walls of the houses at Sennehoo. What 

 happened in the upper parts of the country is, of course, not 

 known, but the force must have been sufficiently severe to im- 

 press the people and influence them as they appeared to have 

 been. 



(3) It is remarkable that tliese vibrations, which seemed to 

 have been extensive throughout the Bompeh District, and which 

 seemed to have been so distinct, are almost simultaneous with 

 those experienced in some places in the Mediterranean Sea, in 

 Greece, and notably at Ch.arleston, on the Atlantic coast of 

 America, where their effects were so disastrous. 



(4) The Bompeh, like the Ribbee and Cockborough Rivers, 

 runs into Yawry Bay, which is an arm of the Atlantic, and the 

 Bompeh District, on the eastern side of this ocean, is opposite 

 to, and not many degrees of latitude below, the scene of the late 

 disasters in America. 



(5) I think it my duty to make this communication, as the 

 information might possibly be of use to scientists engaged in 

 the study of the facts connected with the range and transmission 

 of these seismic disturbances. 



(Signed) Jos. M. Metzger, Manager 

 Kent, Western District, October 20, 1886 



SCIENTIFIC SERIALS 



American yoiiriial of Science, November. — The higher oxides 

 • i( copper, by Thomas B. Osborne. The oxides here dealt with 

 .ire copper dioxide and copper sesquioxide ; but being unable to 

 continue the subject, at least for some time, the author publishes 

 ilie incomplete results so far obtained, in the hope that they may 

 lie of use to others wishing to continue this line of investigation. 

 — The structure of the Triassic formation of the Connecticut 

 N'a'ley, by William Morris Davis. It is shown that disturbance 



has taken place after the period of deposition ; that it was not 

 caused by overflow or intrusion of trap-sheets ; that it was not a 

 simple monoclinal tilting ; and that there is evidence for occur- 

 rence of unseen faults. The probable character of the disturb 

 ing force, its action on the fundamental schists, with consequent 

 monoclinal faulting of overlying Triassic strata, and generally the 

 area and depth of the disturbance, are questions also discussed in 

 this elaborate paper. — Researches on the lithia micas, by 

 F. W. Clarke. Descriptions and exhaustive analyses are given 

 of the lepidolites of Rumford, Hebron, Auburn, and other parts 

 of Maine, and of the iron-lithia micas of Rockfort granite- 

 quarries near Cape Ann, Massachusetts. — The thickness of the 

 ice in North-Eastern Pennsylvania during the Glacial epoch, by 

 John C. Branner. So far from rising only 2200 feet above sea- 

 level, as hitherto supposed, the ice is shown to have covered the 

 twin peaks of Elk Mountain (2700 and 2575 feet), and no doubt 

 also the Sugar Loaf, Ararat, and the other loftiest summits of 

 this region during the Glacial epoch. A sheet of ice 1500 feet 

 or less in thickness could never have flowed across such a moun- 

 tainous region, so regardless as the great glacier was of its 

 marked topographical features. —On the time of contact between 

 the hammer and string in a piano, by Charles K. Wead. 

 Owing to the uncertainty attending the theoiy developed by 

 Helmholtz regarding the action of the hammer on a piano string, 

 the author has attempted to measure directly the time of contact 

 by a simple process with results here tabulated. — Photographic 

 determinations of stellar positions, by B. A. Gould. This is 

 a reprint of the paper presented at the late Buft'alo meeting of 

 the American Association, and containing a brief history of 

 stellar photography, and of the results so far obtained by the 

 author in this department of practical astronomy. — Lucasite, a 

 new variety of vermiculite, by Thomas M. Chatard. A de- 

 scription and full analysis is given of this substance, specimens 

 of which have been found associated with corundum at Corundum 

 Hill, Macon County, North Carolina. It has been named 

 lucasite in honour of Dr. H. S. Lucas, so well known in con- 

 nection with the Chester emery mine, Massachusetts. — Crystallo- 

 graphic notes, by W. G. Brown. An account is given of cer- 

 tain artificial copper crystals, of artificial crystallised cuprous 

 oxide (cuprite), and of crystallised lead carbonate (cerassite) 

 found under circumstances here described. — On the chemical 

 composition of ralstoaite, by S. L. Penfield and D. N. Harper. 

 A comparative table is given of the analyses made by Nordens- 

 kjold, Penfield, and Brandle of this rare mineral, which was 

 found associated with thomsenolite at Arksuk Fjord, Greenland. 

 — Analyses of the thomsenolite by the same chemists. — Mineralo- 

 gical notes, by Edward S. Dana. Descriptive analyses are given 

 of columbite from Standish, Maine, of diaspore from Newlin, 

 Pennsylvania, of zincite from Stirling Hill, New Jersey, and of 

 some native sulphur from Rabbit Hollow, Nevada, interesting 

 because of its complex crystalline form. 



Rivista Scientifico-Induslria/e, October.— On the cause of the 

 magnetic rotatory polarisation, by Prof. Augusto Righi. Fres- 

 nel's hypothesis having been proved inadequate by recent ex- 

 periment, the author has resumed the subject, with the view of 

 ascertaining whether it may be explained by the reflected or 

 transmitted vibrations of bodies endowed with rotatory power. 

 If the incident polarised ray on penetrating a body is really de- 

 composed into two inverse circular rays endowed with difterent 

 velocities, the intensity of the two rays must also vary both in 

 the reflected and transmitted light. The ray possessing greatest 

 velocity of propagation, and consequently a lower index of re- 

 fraction, must possess least intensity in the reflected and greatest 

 in the transmitted light, assuming the two indices to be greater 

 than unitv, as in the opposite case the result would be reversed. 

 Hence both the reflected and transmitted ray will become ellipti- 

 cal ; and Prof. Righi has succeeded in determining this ellipticity 

 by employing iron, the body endowed whh the greatest rotatory 

 power. The elliptical vibration of the reflected ray is in the 

 opposite direction to that of the magnetising current, while that 

 of the transmitted ray is in the same direction. In a future com- 

 munication it will be shown that this agrees with the hypothesis 

 of double circular refraction. — On the tests of fatty substances, 

 and especially of olive oil, by Professors G. B. Bizio and L. 

 Gabba. This paper contains a critical inquiry into the methods 

 of testing the purity especially of olive oil, and it concludes that 

 none of the processes now in use are absolutely trustworthy. 

 Even that of Bechi fails to distinguish with certainty between 

 olive and cotton oil. 



