Nov. 17, 1887] 



NATURE 



51 



this: " We have found that the resistance of secondary 

 cells of the various dimensions which we have used 

 varied from 2 to 5 metres of a copper wire i millimetre 

 in diameter" (p. 64), show that M. Plants sought for 

 greater exactness in his measurements than many of his 

 contemporaries during the infancy of the electric accumu- 

 lator. 



It was to be expected that in suggesting yet untried 

 applications of secondary batteries the author should 

 make statements which any student now knows to be 

 erroneous. An example is to be found at p. 105, 

 where it is suggested that, by using a secondary bat- 

 tery, two ordinary Bunsen cells might be enabled to 

 work a continuous voltaic arc. As was also to be ex- 

 pected in such a republication of papers as this, many of 

 which read like the contents of an inedited laboratory 

 note-book, there are repetitions of the same facts and 

 sentiments. 



Unfortunately there is another resemblance to labora- 

 tory notes in much of the matter of this book which 

 cannot be so readily forgiven. One often confides to 

 one's note -book a speculation which is based on a very 

 far-fetched resemblance between two phenomena. And 

 it is quite possible to find in a note-book such a note 

 as this (p. 198) : " The experiment described above (158) 

 in which a cloud of metallic oxide, torn from an elec- 

 trode by the current, takes a spiral motion in the body of 

 a liquid under the influence of a magnet, seemed of a 

 nature to explain, in particular, the remarkable form of 

 spiral nebulae." Then follows a description of the nebulae 

 observed by " Lord Ross," and the further remarkable 

 note : " In view of so striking a similarity, may it not 

 be reasonably supposed that the nucleus of these nebulae 

 may be formed by a veritable electrical furnace ; that 

 their spiral form is probably caused by the presence of 

 celestial bodies powerfully magnetized, and that the direc- 

 tion of the curve of the turns in the spiral must depend 

 upon the nature of the magnetic pole turned towards the 

 nebula." 



This sort of thing may be found in the note-book of 

 almost any laboratory worker, but it is astonishing to find 

 that M. Plants has not only published it in the proceed- 

 ings of a scientific Society, but actually publishes it again 

 after he has had many years of leisure for reflection and 

 for verification. These speculations occupy many chapters 

 of the book. M. Plants describes some natural pheno- 

 menon, such as globular lightning, the formation of hail, 

 water- spouts, cyclones, the aurora, atmospheric electricity, 

 spiral nebulae, or solar spots ; he then begins to write on 

 the vague analogy existing between this natural pheno- 

 menon and some isolated phenomenon observed by him 

 in the laboratory, and after he has written some pages, 

 the analogy becomes very indistinct ; but he continues to 

 write in the hope that if he writes long enough he may 

 obtain clearer ideas. Of the same kind are his " views" 

 of the nature of electricity. He finds that when successive 

 intense currents are sent through fine wires, which are, of 

 course, greatly heated, the wires lose their straightness in 

 curious ways. It is very interesting to read about the 

 observed phenomena, but unfortunately we have the 

 author's speculations as well. He says (p. 247) : — " The 

 phenomena we have just described (313-20) are of a 

 nature to throw some light on the mode of propagation of 



electricity. The molecular vibrations revealed by knots 

 formed in a metallic wire, by the curious noise, and by a 

 notable change in its cohesion under the influence of the 

 passage of the dynamo-static current which we have just 

 studied, must be produced in a lesser degree in conduct- 

 ing substances traversed by electric currents of very low 

 tension. This vibration may be too feeble to be per- 

 ceptible, but it is not the less real. We are then able to 

 conclude that the electric movement must diffuse itself in 

 substances after the manner of a purely mechanical 

 motion, by a series of very rapid vibrations of the more 

 or less elastic matter through which it passes." 



He then goes on in his last chapter, without a thought 

 of the possibility that very rapid heating of a not per- 

 fectly homogeneous conductor might explain his pheno- 

 mena, to build up a theory of electricity from these iso- 

 lated facts with the help of a few far-fetched analogies, 

 and he publishes his theory without further verification. 

 In spite of our great obligations to M. Plantd,we feel that 

 he has set the very worst example possible to the probable 

 readers of his book, in publishing these vague speculations 

 of his. John Perry. 



FRirSCWS CRUSTACEAN FAUNA OF THE 

 CHALK OF BOHEMIA. 



Die Crustaceen der Bbhmischen Kreideformation . Von 

 Prof. Dr. Anton Fritsch und Jos. Kafka. Pp. 55. 

 (Prague : Selbstverlag, in Commission von Fr. 

 Rivndc, 1887.) 



THERE is probably no sedimentary deposit in the 

 whole series of the stratified rocks with which one 

 is more familiar than the Chalk. This is doubtless due 

 to its peculiar whiteness, and to the fact of its occupying 

 so large an area in our eastern and south-eastern coun- 

 ties, and its prominence in the coast-sections of York- 

 shire, Kent, and Sussex, and the opposite coast of France ; 

 forming at Dover those white cliffs which gave to our 

 shores their ancient name of Albion. 



In the Cretaceous formation, however, we include a set 

 of other beds, very dissimilar from the Chalk in appear- 

 ance and composition, but which, on stratigraphical and 

 palaeontological grounds, seem to form a natural rock- 

 system. These are known as the Upper Greensand, the 

 Gault Clay, the Lower Greensand, and the Wealden Beds, 

 comprising marls, sands, clays, and even fresh-water 

 limestones. Without entering into details as regards 

 the minor divisions, we may say that the major 

 proportion of these deposits are marine, as shown by 

 the organic remains contained in them. The Chalk itself,, 

 from its general purity, must have been formed in a 

 deep and open sea ; indeed, the researches which 

 have been carried on in the North Atlantic Ocean 

 show that the materials for a continuous bed of Hmestone 

 with flint-nodules are now being deposited at depths of 

 from 400 to 2000 fathoms, while many forms of life met 

 with there are analogous to those of the Chalk. 



That this old Cretaceous sea must have been of very 

 wide extent is proved by the enormous area over 

 which its sediments have been traced, as shown on 

 our geological maps ; whilst outliers and vast beds of 



