-3fi 



NA TURE 



[August 6, 1903 



themselves, either vi&. the pedicels or from outside, 

 and the author gives an instructive set of figures 

 illustrating the development of the flower and young 

 fruit in connection with chapter v. 



Chapter vi. is concerned with the development of the 

 fungus in the different organs of the vine, and with 

 descriptions and figures of its numerous reproductive 

 phases, comprising two forms of conidia, two forms 

 of pycnidia, the perithecia, and certain sclerotium-like 

 stages. 



In chapter vii. the results of pure cultures are 

 described, and the conclusion established that the 

 spores may germinate in rain-water, and the young 

 mycelium suffer desiccation, and again revive if 

 wetted; further, that spores germinating on the sur- 

 face of the plant may remain alive and active for as 

 much as six days, in damp weather, awaiting a 

 moment favourable for infection, as it were. Dry 

 spores may be kept twenty-three months, and still 

 germinate on placing in water. The numerous mor- 

 phological details must be passed over here. 



In chapter viii. the various modes of infection are 

 dealt with, and the results are that the fungus may 

 enter by the pedicel, by the peduncle or one of its 

 branches, or at the articulation of the fruit to its stalk, 

 or it may enter the fruit directly. A valuable series 

 of coloured figures shows the various tints assumed by 

 the diseased grapes, and we are reminded of one form 

 of the disease termed " shanking " in this country. 



Chapter ix. is devoted to the experimental infec- 

 tions. Many points of interest are given here, e.g., 

 the tips of the germ-tubes directly dissolve the cuticle ; 

 a cellulose dissolving enzyme also occurs; liquefied 

 walls resist attack, &c. 



Chapters x. to xli. deal very thoroughly with treat- 

 n'.ent, and the numerous experiments show that cal- 

 cium bisulphite and free sulphurous acid are prac- 

 tically the only efficacious remedies, Bordeaux mixture 

 and other copper compounds, or mixtures, as well as 

 several other media being found useless. 



In chapter xiii. an account is given of the various 

 other fungi which may accompany the Coniothyrlum. 

 Chapter xiv. is devoted to a discussion of the sys- 

 tematic position of the fungus, while chapter xv., and 

 last, again returns to the question of treatment, this 

 time dealing with It In the form of advice as to 

 methods, quantities, periods, &c. 



There can be no question that Istvdnffi's memoir 

 has a three- fold importance, (i) to the vegetable 

 pathologist, owing to the clear and exhaustive account 

 of the parasite and Its relations to the host ; (2) to .the 

 histologlst and morphologlst, because it contains so 

 many interesting anatomical details concerning the 

 host and Its parasite, and (3) to the practical vine- 

 grower, who will get from It one of the best accounts 

 of symptoms and treatment we have ever met with. 



The scientific value of Istvdnffi's book Is un- 

 doubtedly dependent on his clear recognition of the 

 fact that, to deal properly with any parasitic disease, 

 it Is essential to take into account not only the peculi- 

 arities of the fungus, but also the reactions of the 

 host-plant. 



The one great fault we have to find with it is the 

 want of summaries to the several chapters and to the 

 whole work. 



NO. 1762, VOL. 68] 



OVR BOOK SHELF. 



Kinemaiics of Machines. By R. J. Durley, B.Sc, 

 Ma.E. Pp. viil + 379. (New York: John Wiley 

 and Sons; London : Chapman and Hall, Ltd., 1903.) 

 Price 17s. net. 



This Is a carefully written elementary text-book deal- 

 ing with the subject from the Reuleaux standpoint. 

 In the first chapter the author introduces the notions 

 of kinematic links and chains and the pairing of 

 elements, and gives some fundamental propositions re- 

 lating to degrees of freedom and constraint, and to 

 instantaneous centres and centrodes in plane motion. 



The next chapter treats pretty fully of motion In a 

 straight line and about a fixed axis. Position, velocity 

 and acceleration, linear and angular, in regard to both 

 time and displacement, are exhibited by means of 

 rectangular and polar diagrams, and problems are 

 worked by graphical processes, the scales for measur- 

 ing the results beings always most carefully determined- 

 The alternative, and often more desirable method of 

 tabulation and the numerical calculation of differences 

 seems to have been overlooked; It might well have 

 been introduced and illustrated in an example like that 

 of the. electric car found on p. 47. Several problems on 

 simple harmonic motion are given ; but the author is 

 scarcely alive to the great and growing Importance ot 

 this branch of the subject. The fruitful idea of a 

 rotating vector Is not fully taken advantage of. A few 

 additional pages are all that would be required in order 

 to show how, In many cases of periodic motion, being 

 given or having plotted a number of suitable positions 

 in the cycle, the motion could be quite easily analysed 

 and expressed approximately in the first three or four 

 terms of the Fourier series, and thus readily compre- 

 hended and dealt with. 



In the next two chapters the various mechanisms 

 contained in the quadric and slider crank chains are 

 well described and excellently Illustrated. In all the 

 more important cases the relations between the linear 

 and angular velocities and accelerators are obtained 

 both graphically and analytically, the principles estab- 

 lished In the first two chapters being now applied. 



Chapter v. Is interesting, being an investigation of 

 the motion In plane mechanisms In general. The 

 author establishes and uses the velocity and acceler- 

 ation Images of Prof. R. H. Smith. As an example 

 it is shown how to find the velocity of any point in a 

 Stephenson link. The direct and powerful method of 

 working from point paths is also illustrated, but is 

 deprecated on account of Its supposed inaccuracy. We, 

 however, have found that, by the use of suitable appli- 

 ances, large scale plotting can be carried out ex- 

 peditiously, and with a degree of precision which 

 render it possible to obtain not only velocities, but 

 accelerations (or second differences), with quite sur- 

 prising accuracy, and sufficient for most purposes. 



Subsequent chapters relate to mechanisms contain- 

 ing higher pairing and non-rigid links, illustrated by 

 spur gearing, cams, ratchets, escapements, belt and 

 chain gearing, springs, chamber trains, &c. And 

 there are chapters on screw and spheric motions, the 

 latter containing an instructive Investigation of the 

 rolling and spinning velocities in various types of ball- 

 bearings. The book concludes with a short historical 

 account of the attempts which have been made to 

 classify mechanisms. 



The rigid exclusion of kinetics and of all dynamical 

 considerations from a book like the present seems 

 artificial, and to restrict Its value; but those who do 

 not take this view, and who follow Reuleaux, will 

 welcome the volume. The descriptions are clear, the 

 illustrations well selected, and the diagrams beauti- 

 fully executed. Graphical and analytical calculations 

 are judiciously mixed without an undue use of either. 



