AT- 



NA TURE 



Oct. 



1S72 



of the aurora borealis hardly deserves such a favourable 



criticism. 



As usual with almost all treatises on Natural Philo- 

 sophy, wc have to find fault with the character of the very 

 few remarks which are devoted to terrestrial magnetism ; 

 but we know of no elementary book which deals with that 

 very interesting subject sufficiently, and of hardly any 

 which deal with it correctly. 



The explanation of the principle of the telegraph is very 

 lucid, and the diagrams connected therewith are exceed- 

 ingly well adapted for enabling the learner to grasp the 

 principle. The accompanying pair of diagrams in illus- 

 tration of the principle of Morse's Telegraph leave hardly 

 any verbal explanation necessary. 



Diagrams of a self-explanatory character, and which, 

 to a certain extent, stand in place of words, form a very 

 useful feature in an educational text-book. 



Jas. Stuart 



OUR BOOK SHELF 



yahiiiiicli dc-r kaiserlich-kottiglichcn gcolo^ischcii Rci^hs- 

 aiistalt. No. I, 1872. Band xxii. (Wien.) 



This part of the Year-book contains three papers devoted 

 to the mining industries of Austria. In one of these — 

 "On the Future of Mining in Austria," l3y Constantin 

 Freih. v. Eeust, we liavc concise and interesting sketches 

 of the several mineral-bearing regions of Bohemia and 

 Moravia, as also of the various rock formations (jf the 

 Alpine districts which arc metalliferous. The author 

 comes to the conclusion that mining in Austria is capable 

 of vast development, there being goodly stores of silver, 

 lead, zinc, iron pyrites, and even perhaps of gold, which 

 only require energy and enterprise to win them. The 

 same writer contributes a second paper, " On the Direc- 

 tion of the principal Veins in the non-Hungarian Lands 

 of the Austro-Hungarian Monarchy." Franz Ritter v. 

 Hauer also gives some account of tlic ironstones worlced 

 by the Styrian Iron Company near Eisenerz. Dr. Emil 

 Tietze has a long and able memoir on the geology and 

 ]jaLeontology of the southern regions of the Banat moun- 



tains (Hungary). The descriptions of cretaceous and 

 liassic fossils, many of which arc of species new to science, 

 and the illustrative plates that a'ccompany the mvuioir, are 

 well worthy the attention of palaeontologists. In tl\e 

 I\Iiiici-aloii!schc MitlhcititUi^cn, edited by I'rof. Tschermak, 

 we have, amongst a number of other papers, one by Piof. 

 InostranzclT of Petersburg, giving the results of his exa- 

 mination of certain limestones and dolomites as bearing 

 on ([ucstions of metamorphism. Prof. A. Exner, of 

 Vienna, also contributes a " Chemical Examination of 

 the Meteorites of Gopelpur." Other papers by M. Websky, 

 A. Brezina, and F. Babanek, on mineralogical subjects, 

 will serve to sustain the reputation acquired by our Ger- 

 man friends in a department of science which has far too 

 few votaries in this country. 



The Metric System of \Veii;hts and Measures : an Ad- 

 dress delivered before the Convocation of the Uni- 

 versity of the State of New York, at Albany, August i, 

 1871. By Frederick A. P. Barn.ard, S.T.D., LL.D., 

 President of Columbia College, New York City, &c. 

 (New York, 1872.) 



Principal Barnard was appointed, in 1871, by the 

 Trustees of the University of the State of New York to 

 attend a meeting of the Convocation of that University, 

 who were adverse to the introduction of the Metric 

 System, and to enlighten them as to its real nature, and the 

 immense advantages that would flow from its adoption. 

 He seems to liave performed his duty with great ability, 

 and we hope witli equal success. This volume contains 

 a revised edition of that address, with considerable addi- 

 tions in the form of notes and appendices. Principal 

 Barnard gives a very lucid account of the origin and 

 nature of the metric system, narrating the recent progress 

 of meteorological reform, and answering with what ap- 

 pears to us unassailable arguments the objections com- 

 monly urged to its universal introduction into all civilised 

 communities." One appendix contains a long, inte- 

 resting and useful dissertation on the Unification of 

 Moneys, with some well-arranged infotmation on wliat 

 has already been prepared and done. In another ap- 

 pendix he describes and discusses the various experiments 

 which have been made to fix on a standard for measures 

 of capacity. His third appendix is on the legislition of 

 Great Britain and of British India in regard to the metric 

 system ; and his last appendix contains some very inte- 

 resting, and what many will deem astonishing, statistics on 

 the extent to which the system has been already adopted. 

 From this we learn that France, Spain, Holland, Belgiunr 

 (and their colonies), Portugal, Italy, the North German Con- 

 federation, Greece, Roumania, British India, and nearly 

 the whole of the countries of Central and South America, 

 have adopted the metric system in full ; they represent a 

 population of 336,419,595. Wurtemburg, Bavaria, Baden, 

 Hesse, Switzerland, Denmark, Austria, and Turkey, re- 

 presenting a population of 84,039,209, have adopted metric 

 values ; while m Great Britain and the United States, 

 containing a population of 70,373,091, the system is still 

 permissive. In Sweden'and Norway (population in 1867 

 5,897,159) the decimal division has been adopted without 

 the metric values. Thus the peoples already decidedly 

 enlisted on the side of tlie system include a total popula- 

 tion of about 420,000,000. This looks hopeful, and there 

 seems no doubt that this rational system of weights and 

 measures will ere long be universally adopted. One very 

 remarkable fact the author mentions in confirmation of 

 this. At the close of last century, the simple measure of 

 length called the foot had not less than sixty difterent 

 values — probably many more — actually in use in dif- 

 ferent parts of Europe ; in 1867, there could be found only 

 eii;/!t of this discordant class surviving. We would re- 

 commend Dr. Barnard's book to all who wish to possess 

 a clear and intelligible account of the system and its 

 many adv.n.ntagcs within a moderate compass. 



