Intelligence and Miscellaneous Articles. 301 



book of reference. The boundary of mathematical science forms, 

 year by year, an everwidening circle, and the advantage of having 

 at hand some condensed statement of results becomes more and 

 more evident. To the original investigator occupied with abstruse 

 researches in some one of the many branches of Mathematics, a 

 work which gathers together synoptically the leading propositions 

 in all, may not therefore prove unacceptable." In an undertaking 

 of such magnitude it would not be difficult to detect faults, but 

 these are in the main corrected by the lists of Errata ; and some 

 others, as the unfortunate wrong numbering of a limited number 

 of sections in Section viii., which is indicated on p. 473, are allowed 

 for in the Index. Every subject that can be classed under the 

 head of Pure Mathematics, with the exception perhaps of Quater- 

 nions, appears to us to have been carefully treated on the author's 

 lines. A little difficulty is at first experienced in working with 

 such a vast Index ; but it will be found with use that this part is 

 as carefully done as the rest of the work. To many of our readers 

 a most useful part will be found to be comprised in that portion 

 which is represented by the closing words of the titlepage, 

 " Supplemented by an Index to the Papers on Pure Mathematics 

 which are to be found in the principal Journals and Transactions 

 of learned Societies, both English and Foreign, of the present 

 Century." These are thirty-two in number, are tabulated with 

 great care, and references to the British Museum Catalogue are 

 appended. This is such a valuable feature of the book that we 

 should like to see the list considerably extended, so as to include for 

 instance references to our own columns, in which from time to time 

 most important articles on Pure Mathematics have been furnished 

 by Cayley, Sylvester, Boole, and others of our leading men. 



The typography, arrangement of text, colour of paper, and 

 figures leave little, or we would rather say nothing, to be desired, 

 for readers can consult the book with comfort under almost any 

 light. 



XXXV. Intelligence and Miscellaneous Articles. 



ON THE ACTION OF THE DISCHARGE OF ELECTRICITY OF HIGH 

 POTENTIAL ON SOLID PARTICLES SUSPENDED IN THE AIR. BY 

 A. VON OBERMAYER AND M. VON PICHLER. 

 rPHE purification of air from dust by electrical discharges has been 

 -*- observed by Aitken (' Nature,' vol. xxviii. p. 322), and Lodge 

 (Phil. Mag. [5] xvii. p. 214). The authors have examined the dis- 

 charges of a double-influence machine in turpentine-smoke; this 

 was contained in a glass tube, 11 centim in diameter and 111 cen- 

 tim. in length, provided with brass mounts. The discharge took 

 place between rods provided with combs at the ends, and which 

 were supported in insulated mounts nearly parallel to the axis of 

 the tube. The smoke was deposited in large flakes near the combs 

 in less than a second. The spark of an induction-coil and of a 



