Oct. 25, 1877] 



NATURE 



543 



importance. It is not too much to say that when the 

 author is unable to copy from a clear-headed and accurate 

 writer, such as von Sonklar/'this part of his work is 

 frequently a mere muddle. 



In attempting to subdivide the Alps] into separate 

 groups it is possible to apply one or other of two guiding 

 principles. You may look either to. the configuration of 

 the surface and make the deep valleys and low passes 

 that occur here and there throughout the chain the boun- 

 daries between the different groups, or you may attend 

 mainly to geological structure, and form groups in each of 

 which a central mass of crystalline rock is surrounded by 

 a girdle of sedimentary strata, but in so doing must often 

 disregard the actual features of the country. M. Pfaff has 

 alternately adopted the geological grouping of Studer and 

 the orographic arrangement of von Sonklar, with the 

 natural result that the same mountains and valleys are in 

 some cases included in two different groups while others 

 are left utterly unprovided for, there being no one group 

 in which they can be placed. For some groups the 

 author has attempted to assign limits and specify the 

 higher summits, but considering the ill success of these 

 attempts, he has, perhaps wisely, refrained in other cases, 

 and for eleven groups he has given names without at- 

 tempting to define their limits. Among the dominant peaks 

 we find the two ancient impostors Mont Ollan and Mont 

 Isdran, whose existence has long since been disproved 

 by the active members of our Alpine. Club, and, stranger 

 still, we are told to look for the latter in an utterly new 

 direction — in the range west of the Col de Bonhomme 

 "between the Is&reand the Rhone" — where the discovery 

 of a mountain over 13,000 feet high would undoubtedly 

 make a lively sensation among the natives. A list of 

 the most important peaks in the Alps is given, in which 

 are enumerated fourteen summits in the mass of Mont 

 Blanc, and twelve of those of Monte Rosa, while the 

 crowning peaks of other important groups such as the 

 Grand Paradis and Piz Bernina, each well above 13,000 

 feet, are altogether omitted. Heights copied at random 

 from various authorities are hopelessly irreconcilable. 

 In one page the Gross Glockner is 495 English feet higher 

 than the Ortler Spitz ; a few pages later the tables are 

 turned, and the Ortler surpasses his rival by 285 feet. 

 \Yhat with errors in the spelling of names, confusion of 

 standards — Paris feet being quoted in one line, Vienna 

 feet in the next, and in the third some other foot differing 

 from both — and arithmetical blunders or misprints, this 

 portion of the book is simply bewildering. 



Under the head of meteorology the author discusses 

 at much length the laws connecting the decrease of 

 temperature of the air with increasing elevation above 

 the earth's surface. He gives the now-antiquated formula 

 of S. von Waltershausen as in accordance with observa- 

 tion, and then professes to give the results of what, 

 wiih characteristic accuracy, he describes as the " obser- 

 vations of Glaisher and Coxwell, who, on September 5 

 1862, in London, rose to the astonishing height of 

 26,800 feet" (28,565 English feet). The reader who 

 may turn to the report of Messrs. Glaisher and Cox- 

 well's famous ascent from Wolverhampton will fail to 

 find anything in the least resembling the results here 

 given, these being in truth very incorrectly calculated 

 from the average results of all the ascents made in 1862. 



No reference is made to the 'bearing of these or other 

 recent investigations on a matter so interesting to Alpine 

 travellers as the measurement of heights by means of the 

 barometer, nor does Prof. Pfaff seem to be acquainted 

 with the various memoirs by Count St. Robert, of Turin, 

 wherein the whole subject is discussed in a masterly 

 manner. 



Fully one-third of the volume is devoted to the glaciers 

 wherever it would appear that the writer has made 

 observations on his own account. In this branch of his 

 subject he is moderately well informed, and no doubt has 

 done his best to steer cautiously through the rocks and 

 shoals of personal controversy with which the history of 

 this department of scientific inquiry is unfortunately sur- 

 rounded, while at the same time he fails to mark ^accu- 

 rately the positive contributions of each inquirer to the 

 present sum of our knowledge. 



He gravely discusses the dilatation theory of glacier 

 motion, and comes to the conclusion that " dilata- 

 tion cannot be considered the only cause of the 

 progressive motion of glaciers," and soon after remarks 

 that the gravitation theory has now a majority of 

 adherents ; while it would be difficult to name a single 

 competent authority who during the last twenty years 

 has admitted .that dilatation has any share whatever in 

 producing the phenomena. He has doubtless read the 

 writings of Agassiz, and Forbes, and Tyndall, but he 

 shows himself unable to grasp the full force of the 

 reasoning of the two latter writers, and in more than one 

 instance has failed to understand them. With regard to 

 the vexed question of the origin of the veined structure of 

 glacier ice, Prof. Pfaff is especially unsatisfactory. He 

 attributes the first notice of it to M. Guyot, though many 

 previous travellers had like him observed it, but failed to 

 discern, as Forbes first did, its significance and import- 

 ance ; and he further on confounds the dirt bands of 

 Forbes with the superficial appearance of the veined 

 structure. Especially imperfect and indefinite is the 

 version here given of Tyndall's explanation of the origin 

 of this structure ; no reader would be likely to appreciate 

 from these pages either the cogency of the arguments in 

 favour of that explanation, or the difficulties which yet 

 remain to be completely removed. 



To those who are used to look for accurate knowledge 

 and scrupulous care in German scientific works, it is 

 disappointing to find that volumes designed for popular 

 instruction in that country should be so deficient in all 

 the requisites for imparting knowledge to unscientific 

 readers, as this and some others which have lately 

 appeared. 



OUR BOOK SHELF 



I-^ryptogainien Flora von Schlesien. Erster Band. 



(Breslau ; J. U. Kern's Verlag, 1S76,) 

 This flora is dedicated to the president of the " Schle- 

 sischen Gesellschaft fiir vaterlandische Cultur," Prof. 

 Goeppert, on the fiftieth anniversary of his receiving his 

 doctor's degree. The whole has been ably edited by 

 Dr. Ferdinand Cohn. It is proposed to continue the 

 flora in two more volumes, one devoted to the Algas and 

 Lichens, and the third to the Fungi, but two years more 

 must elapse before the completion of the entire work. 

 The first volume includes two parts, the first contain- 

 ing the Vascular Cryptogams and Mosses, the second 



