August 15, 1889] 



NATURE 



365 



by Plateau : in Germany by Koch, W. Miiller, and 

 Zaddach, whose type species were very generously in- 

 trusted to Brady and Norman by Prof. Seeliger, of 

 Konigsberg. In France, the species have only quite 

 recently been investigated by Moniez. Those of Great 

 Britain are the only ones at all extensively worked out. 



This monograph, which consists of 200 quarto pages, is 

 illustrated with fifteen plates, and is published as Part II. 

 of the fourth volume of the Transactions of the Royal 

 Dublin Society. j 



The Harpur Euclid. Books I. — IV. By E. M. Langley 

 and W. S. Phillips. (London : Rivington, 1889.) ' 



This is an edition of the " Elements " " revised in accord- | 

 ance with the Reports of the Cambridge Board of 

 Mathematical Studies, and the Oxford Board of the 

 Faculty of Natural Science." The favourable impression 

 made upon us by the two previous instalments of Books 

 I. and 1 1, is thoroughly confirmed by the additional matter ] 

 now before us. We are not going to say that it is the j 

 best edition we have seen, for lately we have had under | 

 our notice two or three excellent works on much the same 

 lines, but it is certainly not inferior to any of these, 

 whilst for the arrangement of the text, the variety of 

 type, and boldness and correctness of the figures, it is 

 admirably adapted for school purposes. The editors, 

 following on the lines of Mackay's interesting edition, 

 have supplied ample store of illustration and historical 

 matter, which will render the study of" Euclid" interest- 

 ing to the intelligent boy. Not content with embracing 

 within their net an account of Simson's line and the nine- 

 point circle, Mr. Langley, in an article on the principal 

 circles of a triangle, has given an excellent though brief 

 description of the properties of symmedian lines and of 

 the Brocard, cosine, and other modern circles, thus 

 bringing the teaching of these circles within the range of 

 the school curriculum. The exercises now reach the 

 respectable total of 677, and to many of them useful 

 hints for their solution are appended. We await the 

 completion of the authors' task with interest, for a good 

 work on elementary solid geometry is not altogether 

 superseded by Nixon's admirable manual. 



An Elementary Treatise on Mechanics. Part I. Statics. 

 By Rev. J. Warren. (London : Longmans, Green, 

 and Co., 1889.) 



This is an elementary treatise intended for the use of 

 schools and University students. The arrangement and 

 methods of reasoning are best adapted for students who 

 have made some acquaintance with trigonometry. At 

 the same time a considerable portion of the book may be 

 read by those students not possessing such mathematical 

 knowledge. Each chapter contains a good selection of 

 examples, some of which are worked out. This feature, j 

 together with the fact that the various theorems and re- 

 sults are very clearly established, will help to render the j 

 book a useful one. An experimental proof only is given I 

 of the parallelogram of forces, other proofs of which 

 will be found in the second part of the work, which is 

 devoted to dynamics. G. A. B. i 



LETTERS TO THE EDITOR. 



[ Tht Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications. \ 



The Earlier Eruptions of Krakatab. 



At the time when a Committee of the Royal S jciety en- 

 trusted me with the preparation of a sketch of the geological 

 facts bearing upon the great volcanic eruption of Krakata~o in 



i88j, I was quite unaware that any reliable records concerning 

 the early history of the East Indian Archipelago were in exist- 

 ence. I stated, therefore, that authentic history commenced 

 only about three centuries £^0, when the district began to be 

 visited by the Dutch and Portuguese navigators ; and that the 

 earliest eruption of which we have any detailed account was 

 that of 1680, described by Vogel and Hesse. ^ 



At the same time, however, I pointed out that the study of 

 the geological structure of the district — so well described by 

 Mr. Verbeek and by MM. Breon and Korthals — especially 

 when that structure was considered in the light afforded by 

 other volcanic areas that have been investigated by vulcano- 

 logists, led to very definite conclusions as to what must have 

 been the early history of the great volcano. 



It was shown that Krakatab is situated on a fissure traversing 

 the Sunda Strait and running at right angles to the great band of 

 volcanic activity which traverses the islands of Java and Sumatra ; 

 and it was inferred that at a very early period a volcano of great 

 height and bulk was built up at the point marking the inter- 

 section of the two lines of fissure ; it was then stated that — 



"At some unknown period this volcano became the scene of 

 an eruption, or series of eruptions, which, judging from the 

 effects they have produced, must have been on even a far 

 grander scale than that which four years ago attracted so much 

 interest. By these outbursts the whole central mass of the 

 volcano seems to have been blown away, and only an irregular 

 crater-ring left behind. The great crater thus formed must 

 have had a diameter of three or four miles, and its highest por- 

 tions could have risen but a few hundreds of feet above the 

 present level of the sea." 



After pointing out that this crater-ring became to a great 

 extent filled up by a succession of smaller eruptions, I proceeded 

 to say : — 



" Whether the tract now constituting the Strait of Sunda was 

 then dry land uniting the islands of Java and Sumatra, we have 

 no means of determining ; but I may point out that there are 

 some grounds for believing that the formation of the depression 

 occupied by the straits was subsequent to the evisceration of the 

 volcano." 



After stating what these grounds are, I added : — 



" It seems not improbable that the depression between the 

 islands of Java and Sumatra may have resulted from subsidences 

 accompanying or following the ejections taking place at the 

 great central volcanic focus of Krakatab" {loc. cit., pp. 7-8). 



I am greatly indebted to Mr. C. Baumgarten, of Batavia, who, 

 through Dr. R. Rost, the Librarian to the India Office, has 

 called my attention to some ancient records that seem to con- 

 firm, in a singularly striking manner, these conclusions arrived 

 at by scientific reasoning. 



Mr. Baumgarten writes as follows : — 



"In a Javanese book called ' Pustaka Raja,' the 'Book of 

 Kings,' containing the chronicles of the island, kept secret during 

 centuries in the Royal Archives, and only recently made public, 

 we find the following interesting and curious account of an erup- 

 tion of the mountain Kapi : — 



" ' In theyear 338 Saka [/.^. A. D. 416], a thundering noise was 

 heard from the mountain Batuwara,- which was answered by a 

 similar noise coming from ihe mountain Kapi, lying westward of 

 the modern Bantam. A great glaring fire, which reached to the 

 sky, came out of the last-named mountain ; the whole world was 

 greatly shaken, and violent thundering, accompanied by heavy 

 rains and storms, took place ; but not only did not this heavy 

 rain extinguish the eruption of fire of the mountain Kapi, but it 

 augmented the fire ; the noise was fearful, at last the mountain 

 Kapi with a tremendous roar burst into pieces and sunk into the 

 deepest of the earth. The water of the sea rose and inundated 

 the land. The country to the east of the mountain Batuwara, 

 to the mountain Kamula,^ and westward to the mountain Raja 

 Basa,^ was inundated by the sea ; the inhabitants of the northern 

 part of the Sunda country to the mountain Raja Basa were drowned 

 and swept away with all their property. 



" 'After the water subsided the mountain Kapi and the sur- 

 rounding land became sea and the Island of Java ^ divided into 

 two parts. 



' " The Eruption of Krakatab and Subsequent Phenomena," Report of the 

 Kraka'a'b Committee of the Royal Society (1888). 



^ " Now called Pulosari, one of the ext.nct volcanoes in Bantam, and the 

 nearest to the Stra.ts of Sunda." 



3 "Now called the ' (jede ' mountain." 



* •' 1 lie most scuthern volcano cf Sumitra, and situate in the ' Lampung * 

 country." 



5 " The Sanskrit Ymva-dwipa." 



