294 



NA TURE 



[July 30, 1903 



by the camphor specialist. The treatment of the 

 subject is purely theoretical, and in that respect differs 

 from the valuable paper " On the Constitution of 

 Camphor " read at the British Association in 1900 by 

 Dr. Lapworth. 



A short introduction is followed by a chapter giving 

 a rdsumd of the various camphor formulae arranged 

 in historical order, starting from that proposed by 

 Victor Meyer in 1870 and coming down to that of 

 Schryver in 1898. This history of camphor formulae 

 is an interesting example of evolution. The formula 

 proposed by Bredt in 1893, and now generally accepted, 

 seems best to explain the constitution of camphor and 

 its numerous derivatives, and is the one adopted by 

 the author. 



In the third chapter the practical data on which the 

 constitution of camphor rests are recorded under twelve 

 heads, such as " camphor is a ketone," it " contains 

 the group .CHj.CO," " camphor and camphoric acid 

 are saturated compounds," &c., all of which conditions 

 are fulfilled by the Bredt formula. In this connec- 

 tion, to the researches of Briihl on the refractive index 

 might have been added those of Perkin on the mag- 

 netic rotation, as confirming the bridged ring structure 

 of camphor. The inconsistencies of other formulae 

 with the above-mentioned facts are briefly pointed out 

 in the fourth chapter. The degradation products are 

 next treated, and the monograph finishes with a dis- 

 cussion of the constitution of camphene and bornylene. 



The clear manner in which Prof. Aschan indicates 

 how some of the many seemingly inexplicable reactions 

 probably take place is worthy of comment. The 

 dilHculty of excluding unimportant details and in- 

 cluding all that is important in such a monograph as 

 the one under notice has been overcome by the author 

 with great success. J. E. M. 



Theorie der Bewegimgsiibertragung. By Richard 

 Manno. Pp. iv + 102. (Leipzig : Engelmann, 

 1903-) 

 In laying down the fundamental notions of mechanics 

 there has been divergence of opinion concerning the 

 definition of force. There is the distinction between 

 cause and effect, between statics and dynamics. The 

 older school has regarded force as the cause of 

 motion, modern theorists prefer to define and measure 

 force by the effect only. Herr Manno attempts to 

 construct a system of mechanics by regarding force as 

 neither cause nor effect, but as the phenomenon of 

 motion itself, and further, in order to get rid of the 

 notion of action at a distance, every instance of force 

 is supposed to be due to impact, so that motion is 

 transferred from body to body by a succession of in- 

 tervening impacts. Accordingly the attempt is made to 

 develop the theory of impulsive forces from the simple 

 cases of direct and oblique impact. Naturally, in this 

 view, some divergence is found from the ordinarily 

 accepted theory. The proportionality of cause and 

 effect as implied in the " second law of motion " 

 obviously fails when the momentum of a striking body 

 is regarded as producing the momentum of a struck 

 body. 



It must be confessed that the author's theory, when 

 its ^meaning is disentangled from the mass of verbiage 

 with which it is swathed, does not seem to smooth the 

 way towards a clear apprehension of the principles of 

 'mechanics. His leading idea seems to be that purely 

 ■theoretical conceptions, such as action at a distance, 

 must be discarded, and that all the terms used must 

 represent observable phenomena. The author prob- 

 ably has in his mind the subject of a discussion recently 

 ■ appearing in Nature, as is evidenced by sunary physio- 

 logical allusions, and his objection to the technical 

 meaning of " work " when applied to living 

 organisms R. W. H. T. H. 



NO. 1 76 1, VOL. 68] 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



On a Map that will Solve Problems in the Use of the 

 Globes. 



In mapping an extensive region of the earth in separate 

 sheets, there are great advantages in dividing the region 

 into belts by parallels of latitude, and modifying the 

 law of representation in passing from each belt to the next. 

 This plan is illustrated by the accompanying sketch, which 

 represents a region extending from the equator to the North 

 Pole, and covering 80° of longitude. 



The map consists of nine sheets, each covering 10° from 

 north to south, and 80° from east to west. The meridians 

 are indicated at every tenth degree, and are straight lines, 

 all of the same length, at right angles to the parallels of 

 latitude, which are arcs of circles. The two parallels which 

 bound each sheet are on the same scale as the meridians, so 



Fig. 



that the four sides of each of the seventy-two compartments 

 of the map are precisely equal to the lengths which they 

 represent on a spherical globe; and no difference is made 

 between extreme and central meridians, all longitudes being 

 treated alike. The intermediate meridians and parallels 

 will be at right angles, as well as those shown, and the 

 meridians will be of correct length. The interrnediate 

 parallels will be a trifle too short, the defect amounting, in 

 the case of the middle parallel of each sheet, to rather less 

 than I part in 250, a difference too small to be detected by 

 the eye. 



In examining on the map the borderland of two sheets, 

 the two sheets are to be placed in contact at any point on 

 the parallel common to both, and then, on rolling the edge 

 of one sheet against that of the other, the whole border 

 region from end to end will pass in review. All the 

 successive meridians, when they are brought in turn to the 

 point of contact, will be seen as straight lines crossing the 

 point of contact, and the same will be true for the two 

 portions of any oblique line which crosses the boundary. 



If we want to trace a great-circle route from one place 

 to another, we have merely to' roll the sheets into such 

 positions that the points' of contact lie in a straight line 



