Aprils, 1888] 



NATURE 



533 



kurgans. As to the ethnic character of the people 

 who spread them over this vast Scythian region, we 

 have the direct testimony of the traveller Rubruquis, 

 who, when visiting the Polovtzi or Kumans — the scourge 

 of mediaeval Russia — actually witnessed their erection 

 oyer the grave-mounds or kurgans of that race. Their 

 Turko-Tataric origin is indeed entirely borne out by their 

 physiognomy, which, as I have myself had occasion for 

 observing in various parts of Southern Russia, is of an 

 unmistakably Mongolian cast, and their dress and 

 accoutrements thoroughly bear out this identification, the 

 head-gear in some instances being identical with that 

 still worn by some Tekke-Turkomans. Individual diver- 

 gences of type in some of the western examples may of 

 course show that these Mongolian images were imitated 

 by Wendish or Old Prussian, Polish, or Lithuanian 

 hands. Two things, however, may be regarded as 

 certain : that the stone figures of the steppes are of 

 Turko-Tataric origin, and that the date of their Baltic 

 reproductions is considerably later than Neolithic times. 



Arthur J. Evans. 



VOLTAIC ELECTRICITY. 

 Voltaic Electricity. By T. P. Treglohan, Head Master, 

 St. James's Science and Art Schools, Keyham, Devon- 

 port. (London : Longmans, Green, and Co., 1888.) 

 ONE occasionally hears of the evil effects of cram and 

 bad teaching which the system of examination and 

 payment by results so extensively made use of by the 

 Science and Art Department is supposed to encourage. 

 If such books as the above are in general use by teachers 

 or candidates, it cannot be denied that the evil is very 

 serious. 



There is little of reasoning or explanation anywhere ; 

 but, instead, there are strings of statements which would 

 if they were accurate, consist of ready-made answers for 

 such questions as may be set for the first stage or element- 

 ary course of voltaic electricity. At the end of the book 

 will be found the elementary questions in voltaic electri- 

 city for the last twenty years, with numbers attached 

 showing the pages where the answers may be found. 



The book professes to be largely experimental, and 

 the student is urged to make the apparatus and to try 

 the experiments described. A few extracts will show how 

 utterly misleading it is in this respect. 



If the tongue is placed between a penny and a half- 

 crown, ** a feeble spark is seen as contact is made between 

 the two metals." 



electroscopes are recommended to be used. In the figure 

 the plates are shown separated and connected each to the 

 zinc or copper and to one electroscope, of which the leaves 

 are widely divergent. The student is not told that the 

 connections must not be so made, nor is any practicable 

 method of making the experiment described. 



" In brine the positive and negative elements have the 

 same relative order as in dilute acids ; but in ammonia 

 the relation is reversed, and those that were negative in 

 the fo|mer case will be positive in the latter." 



" Itas found that the wire attached to the Cu, C, or Ft 

 has free statical electricity apparent at its terminal, 

 which repels the glass rod rubbed with silk, and that 

 attached to the Zn free statical electricity, which repels 

 the sealing-wax rubbed with flannel." 



Th^ extraordinary statement appears five times in a 

 few piges. 



Three or four Grove's cells are " necessary " to electro- 

 lyze acidulated water ; the hydrogen gas collected in one 

 of the tubes of a voltameter explodes " with a tolerably 

 loud report." When a solution of common salt is electro- 

 lyzed, " the sodium of the salt and the hydrogen of the 

 water " (appear) " where the current leaves the cell." 



" Another simple experiment is to send the current 

 through a solution of iodide of potassium. A brown sub- 

 stance—iodine — is seen at the anode, and the metal 

 potassium at the cathode." 



It is doubtful what some passages mean, as for, instance, 

 the paragraph : 



" If any number of plates be used together, the E M.F. of 

 such a cell would be the result of the difference of potential 

 of the two plates which are furthest apart in the electro- 

 motive series." ^ - 



Frequently, the language is more than careless ; thus, 

 after speaking of sulphuric acid and sulphate of copper, 

 the author says other binary compounds ; and, after 

 describing the action of a solenoid, he says coils and 

 helices also exhibit magnetic properties. 



Those expressions of doubtful meaning — intensity and 

 rquantity — are freely used, as is the word potential, which 

 fortunately has not its meaning explained. The names 

 of some of the units are met with for the first time in the 

 sentence : " Current strength is calculated in amperes, 

 electromotive force in volts, and resistant'^j in ohms." 

 Not a word of explanation is given. 



" The missing Zn " (owing to the action of a voltaic 

 cell) "is found in the cell, either in the liquid or at the 

 bottom, as a grayish-coloured deposit." 



" This " (the bichromate) " was a strong cell, and was 

 tolerably constant ; but, after a short time, was weakened 

 in consequence of crystals of chrome alum forming in the 

 liquid. To prevent this crystallization, the liquid must 

 be frequently disturbed, either by lifting the plates out of 

 it, or by some other means." 



After speaking of the Daniell, Bunsen, and Grove, the 

 author describes the Leclanchd as " another very constant 

 cell." 



To show that zinc and carbon have a greater E.M.F. 

 than zinc and copper in a cell, a condenser and two 



l^ATURAL HISTORY OF VICTORIA. 

 Prodrof^us of the Zoology of Victoria. Decades 1-15. 

 By Prof F. McCoy. (Melbourne, 1878-87.) 



JUST ten years ago. Prof Frederick McCoy decided, 

 uftder instructions from the Victorian Government 

 of the day, to commence the publication of a series of 

 short descriptions, accompanied by coloured figures, of 

 the indigenous members of the different classes of the 

 animal kingdom. These were to be published in 

 parts containing ten plates in each, which have ap- 

 peared with commendable regularity to the present time. 

 As the fauna of Victoria was not as well known as its 

 flora, it was a necessary preliminary, in order to effectu- 

 ally carry out such a scheme, to have a large number of 

 drawings made, as opportunity arose, from the living or 



