50 



NATURE 



[May 1 6, 1889 



to as confirming the view that the present form of the island 

 has only been acquired recently. 



The useful minerals are described in Part III., and 

 their distribution is indicated on the map already re- 

 ferred to. Of most of them Dr. Posevvltz has previously 

 published separate descriptive monographs. 



The rich coal-fields are first described. The seams 

 are exposed in many river cuttings in Sarav.'ak and 

 Brunei. Coal also occurs on the Island of Labuan and 

 in Sabah. There are said to be rich and extensive deposits 

 in East Borneo also, but they have not been worked. 



Gold is of the next importance to coal as a mineral 

 product. Mining in the older formations has hitherto 

 not proved remunerative, the best field being from the 

 diluvial deposits, which are worked almost exclusively by 

 Chinese. The richest gold regions are in the south- 

 east, near Tanah Laut and Kusan, on both sides of the 

 auriferous Meatus Mountains ; and in the north-east, in 

 the Chinese districts of West Borneo and Sarawak. 

 Recently, what jjromise to be rich gold deposits have 

 been discovered in the Upper Segamah River in Sabah. 



The production of gold was much more considerable 

 formerly than it is at present. In West Borneo it amounts 

 annually to 120,000-150,000 kilogrammes, and in Sarawak 

 it amounted to 28,281 kilogrammes in 1886. 



Diamonds are not, comparatively speaking, so abundant 

 as gold, but they occur in the same deposits. They are 

 searched for by Chinese. Since the introduction of the 

 cheaper Cape diamonds, the production has fallen. In 

 1884, 2727 carats were exported from West Borneo, and 

 1200 carats from Sarawak in 1886. 



Dr. Posewitz refers to the late Prof Lewis's speculation 

 as to the connection between diamonds and serpentine 

 {Peridotite) (Nature, vol. xxxvi. p. 571), but states that 

 it is not yet known how far his conclusion is correct, 

 that diamonds and platinum are only found in Borneo 

 in streams which traverse areas containing serpentine. 

 Indeed, it may be added that serpentine is of rare occur- 

 rence in the principal diamond regions of India, and in 

 some of them none whatever has been observed. 



The famous "diamond" of 367 carats, known as the 

 " Matan," from the territorial title of the Rajah to whom it 

 belongs, has been estimated to be worth ^269,378 (Craw- 

 furd). The Dutch made very large offers of money and 

 warlike material for it early in the present century, but 

 these were always refused. The stone, it now appears, 

 was examined in 1868, and proved 10 be only a rock 

 crystal with a specific gravity of 2 63, thus confirming 

 doubts perviously expressed as to its being really a 

 diamond. 



Platinum is of very local occurrence in Tanah Laut only. 



Antimony and quicksilver only occur, so far as is 

 "known, in sufficient quantities to be regularly mined in 

 Sarawak. 



Iron ores are widely distributed, but are of no present 

 economic value. The introduction of cheap European 

 iron has put an end to the native iron industry, as is the 

 case, too, in many parts of India. 



Dr. Posewitz states that the condition of mining 

 industries generally in Borneo is at present very poor. 

 In the south, private coal-mme^ existed, but were put an 

 end to by an insurrection. The well-known Government 

 mines at Pengaron ceased working after thirty-six years' 



existence, as they were no longer remunerative. A private 

 company has now commenced to work valuable mines on 

 the east coast. In Sarawak, mines have been worked by 

 the Government since 1881, and in 1886 produced 44,167 

 tons. In Labuan, mines were also worked for some time, 

 but are now closed. The principal source of supply at 

 present is from Brunei (Muara coal). It is hoped that in 

 the British North Borneo Company's territory extensive 

 workings of gold and coal will be established. 



It is impossible to give here an adequate idea of the care- 

 ful details with which each topic discussed in this work is 

 illustrated. At the same time there is a highly meritorious 

 conciseness of treatment which, together with the sound- 

 ness of the author's views and his careful quotation of his 

 authorities, makes the work a text-book for which it is to 

 be hoped that a competent translator into English and an 

 enterprising publisher will be found. It is emphatically a 

 work which was much wanted, as our knowledge of the 

 geology of this important island has hitherto been most 

 fragmentary and imperfect, and we trust, therefore, thalt, 

 ere long, steps may be taken to make Dr. Posewitz's 

 labours better known to Enghsh readers. V. B. 



GRAPHICS. 



Graphics ; or, the Art of Calculation by drawing Lines, 

 applied especially to Mechanical Engineering. With 

 an Atlas of Diagrams. By Robert H. Smith, Professor 

 of Engineering, Mason College, Birmingham. Part I. 

 (London: Longmans, Green, and Co., 1889.) 



MAXWELL was the first, according to the Intro- 

 duction of the present treatise, to state the 

 principles in a very complete and general manner by 

 which stress-diagrams are drawn, in the Phil. Mag., 

 xxvii., 1864 ; and also in the Trans. Roy. Soc. Edinburgh, 

 vol. xxvi. 



But Maxwell himself is careful to point out that he 

 derived the original idea from Mr. W. P. Taylor, or at 

 least was unaware of his previous use of the method. 



The method is of much greater antiquity, and can be 

 traced through Moselej''s " Mechanical Principles of En- 

 gineering and Architecture," 1843, to Mutton's " Course 

 of Mathematics," 181 1, and probably still further back. 



It is, however, only of recent years that Maxwell's treat 

 ment has been followed up and developed by Cremona, 

 Culmann, von Ott, and others ; and now the method is 

 considered indispensable in practice for the calculation 

 of the stresses in bridges, roofs, and engineering and 

 architectural structures generally. 



Two great advantages of the graphic method recom- 

 mend it to the practical man — the first, that the diagram 

 is itself a check upon the correctness of its construction ; 

 and the second, that the numerical results of the diagram 

 are read off on a scale only to the really practically signi- 

 ficant number of figures, the very roughness and imper- 

 fection of the draughtsman's work showing the margin of 

 variation to be allowed for. 



As to the relative rapidity of the graphic method com- 

 pared with ordinary numerical calculation by logarithms 

 and arithmetical processes, the author points out that, while 

 for a single isolated calculation the graphic method may 

 easily be distanced, it is in the long-continued series of 



