482 



NA TURE 



[March 23, 1899 



the most practically useful. But it was long ago recog- 

 nised in France that this system is only applicable to 

 certain scales, and it was definitely laid down by the 

 "Commission of 1S26" that for scales smaller than 

 1/10,000 this system was insufficient. Then was intro- 

 duced the expedient of "hachures" following the direc- 

 tion of greatest slope {i.e. what we call vertical hachures), 

 and rules were laid down for the spacing of the strokes 

 between the contours. As this is a subject which forms 

 matter for constant discussion even now, it is interesting 

 to note this first endeavour to deal with the problem 

 systematically. No reference is made to horizontal 

 hachuring, which we may presume has never been 

 adopted by the French, although it is found of the 

 greatest practical value in the geographical and military 

 cartography of India. 



The artistic effects gained by the assumed incidence 

 of light is also dealt with ; and here it is quite apparent 

 that Colonel Laussedat's artistic perceptions have domi- 

 nated his judgment. He is all in favour of adopting an 

 affectation of oblique light to gain the effect of relief 

 And there is no doubt that the most perfectly artistic 

 maps yet produced (the Swiss maps of the Alps) owe 

 much of their effect to this expedient. But all theory of 

 a true " diapason " (Colonel Laussedat's own expressive 

 word) of shade to express slopes must disappear, if 

 shadows are to be cast on the sides of mountains for the 

 purpose of rendering them picturesque. .Strong .shade 

 represents steep declivity or precipitousness, and if it is 

 used for artistic effect only, it must lose its prober carto- 

 graphic significance. It cannot be made to answer both 

 purposes. With Colonel Laussedat's view of the utility of 

 elevations and landscapes to illustrate a map we entirely 

 agree, and it is here that the camera lucida and the 

 photograph become effective. The former instrument is 

 often used by geological surveyors in India with most 

 admirable results, and it would be impossible to illustrate 

 the accidents of rock formation in connection with 

 geological maps by any more satisfactory method. The 

 art of photography has not yet been applied to topo- 

 graphical purposes with similar success, but there may 

 be a future awaiting it, with the development of which 

 we trust that Colonel Laussedat will have something 

 to say. 



Incidentally the nature and use of barometric instru- 

 ments are discussed in this book. Just at the present 

 time, when the value of the aneroid barometer is 

 under trial in connection with Colonel Watkins' new 

 invention for throwing the instrument out of gear when 

 not actually in use, this part of Colonel Laussedat's 

 treatise is of special value. It indicates certain irregu- 

 larities in the recording of instruments which he has 

 personally tested, which do not appear to be in accord- 

 ance with those of later observers (VVhymper and others) 

 in England. It may be apropos to this part of the sub- 

 'ect to observe that the use of the aneroid for deter- 

 mining the orography of districts in India and Africa 

 has been largely discontinued lately. With a certain 

 number of fixed altitudes obtained Irigonometrically, it 

 has been found far more satisfactory to use a clinometer 

 in connection with the plane-table. The alidade (or plane- 

 table "ruler") has not been in any way modified for this 

 NO. 1534. VOL. 59] 



purpose 'although the introduction of a scale along the 

 bevelled edge would be an obvious advantage), but a 

 separate instrument carrying a level and a tangent scale 

 is used for interpolating altitudes from fixed points by 

 direct observation. T. H. H. 1 



GOLD MINING. 



The Gold-fields of Australasia. By Karl Schmeisser, 

 Obergrath, assisted by Bergassessor Ur. Karl X'ogel- 

 sang ; translated by Henry Louis, M.A., .A.R.S.M., 

 F.G.S., &c., Professor of Mining, Durham College of 

 Science. Pp. 254 -I- xx. With 13 maps and plans in 

 a separate volume. (London : Macmillan and Co., 

 Ltd. New York : The Macmillan Company, 1898.) 



The VVilivatersrand Gold-fields Banket and Mining 

 Practice. By S. J. Truscott. Pp. xxiii -t- 495. (London: 

 Macmillan and Co., Ltd. New York : The Macmillan 

 Company, 1S98.) 



Transactions of the Institution of Mining and Metallurgy^ 

 London. Seventh Session, 1897-98. Vol. vi. Edited 

 by Arthur C. Claudet, A.R.S.M. Pp. vi -h 34S. 

 (London ; Broad Street House, 1898.) 



THE boom in the Witwatersrand gold mines in 1S95 

 has been attributed, in part at least, to the famous 

 Report made by Herr Schmeisser to the Prussian 

 Government in 1893. Moreover, it is always refreshing 

 to the investing public, weary of the perennial optimism 

 of the ordinary mining expert, to come across an un- 

 prejudiced account of a gold-field written by a man 

 whose reputation and experience give his statements 

 the prestige of a Government Report. A peculiar 

 interest therefore attaches to the appearance of this 

 book, seeing that, with the recent enormous increase in 

 the production of gold, it might have had a great effect 

 on the fortunes of West .Australia. It may, however, 

 be said at once that Herr Schmeisser does not take any 

 definite stand with regard to the land of " sand and 

 sorrow." Certain districts, indeed, he condemns utterly 

 as containing only lodes which pinch out and disappear 

 completely at a very moderate depth, so that they may 

 be expected to cease producing before long. As to 

 other cases, he is still more pessimistic, believing that 

 they depend entirely on pockets of rich ore, which are 

 worked out almost immediately. Moreover, he fears 

 that the generally patchy nature of the lodes will cause 

 many disasters to companies now at work with available 

 capital so small that development and prospecting are 

 checked, and the miners will presently have barren reefs 

 only in sight and no money to search for further rich 

 deposits. 



But, on the other hand, Herr Schmeisser waxes almost 

 enthusiastic over the "composite" veins of Kalgoorlie, 

 and over the possibility of new discoveries which the 

 great unexplored tracts in the interior offer. The 

 composite veins consist of a mixture of quartz veinlels 

 and of clayey or talcose ferruginous rock, passing down 

 at a depth of about 150 feet into undecomposed rock 

 containing sulphides and tellurides of gold and of gold 

 and silver. \'ery rich ore, containing from one to ten 

 ounces of gold per ton, is found in many of the lodes in 



