6 SCIENCE PROGRESS 



1 91 6) of the Arabic MS. on algebra written by Ibn Bahr in a.d. 

 1343 (Nature, 1917,98, 406-7). 



C.Delisle Burns (Mind, 1916,25, 506-12) gives some extracts 

 from William of Ockham's Quotlibeta which show his views on 

 continuity and Zeno's arguments on motion. However, Burns 

 does not notice that these views are apparently borrowed from 

 Roger Bacon, who again apparently borrowed them from an 

 ancient Arabian author. 



G. Loria (Scientia, 1917, 21, 101-21) gives a very good 

 general account of the wa}'s in which imaginaries in algebra 

 have been regarded from the earliest times up to about the 

 middle of the nineteenth century. 



A. Favaro (ibid. 1916, 20, 417-34) criticises in a most learned 

 and convincing fashion the view of the late Pierre Duhem that 

 Leonardo da Vinci's new ideas in statics and dynamics had a 

 large diffusion and a very great influence on thought in the 

 domains spoken of during the sixteenth century and on that of 

 Galileo and his school. Favaro, the editor of the splendid 

 National Edition of Galileo's Opere, examines the thesis, par- 

 ticularly in what concerns Galileo and Benedetto Castelli, and 

 proves, in so far as proof is possible in such a case, the inde- 

 pendence of their work. 



Miss Dorothy Wrinch (Monist, 191 7, 27, 83-104) gives an 

 interesting account of the life and work, particularly part ot 

 the mathematical work, of Bernard Bolzano (1 781-1848), and 

 A. E. Heath (ibid. 1-21, 22-35, 36—56) gives three articles on the 

 life and work of Hermann Grassmann ( 1 809-1 877), the neglect of 

 Grassmann's work, and the geometrical analysis of Grassmann 

 and its connection with Leibniz's geometrical " characteristic." 



H. Bateman (Science Progress, 191 7, 11, 508-12) gives a 

 mainly historical account of the connection of the " calculus of 

 functions " with the theory of integral equations. 



Here we may notice that C. E. Weatherburn (Math. Gaz., 

 191 7, 9, 2-5) makes a plea for a more general use of vector 

 analysis in applied mathematics, and E. B. Wilson (Bull. Amer. 

 Math. Soc. 191 7, 23, 169-72) considers questions in the nota- 

 tions of vector analysis. 



Logic, Principles, and Theory of Aggregates. — Those who 

 know something of what the late Louis Couturat intended to 

 write know that he planned a Manuel de Logistique. The 

 manuscript appears to have been mostly written about 1906, 



