466 



SCIENCE 



[N. S. Vol. LI. No. 1323 



snow itself looked blue-wliite, like paper or 

 sugar " blued " with ultra marine. Evidently 

 the snow, because of its structure, reflected a 

 larger proportion of the short wave-lengths of 

 blue; and we have here another illustration of 

 a structural blue color, which, according to 

 Wilder ■ D. Bancroft " may be obtained when 

 we have finely divided particles of liquid or 

 solid suspended in a gaseous medium (blue of 

 the sky) or a liquid medium (blue of the eye 

 or of the tree-toad) ; or when we have finally 

 divided air-bubbles suspended in a liquid or 

 solid medium (blue feathers).^ 



Incidentally there is some justification for 

 the somewhat brilliant blues used by the artists 

 in painting snow scenes, especially in the 

 shadows; and we recall the story told of 

 Whistler, who, when a lady visitor at his ex- 

 hibition remarked, " I've never seen a sunset 

 like that, Mr. Whistler," promptly replied, 

 "Well don't you wish you could?" 



Jerome Alexajs^der 



EmQEPiELD, Conn. 



SCIENTIFIC BOOKS 



How to Mahe and Use Gi-aphic Charts. By 

 Allan C. Haskell, B.S., with an intro- 

 duction by EiCHARD T. Dana. 539 pages. 

 First edition. Price $5.00. 

 The last years have seen a tremendous 

 progress in the application of graphic meth- 

 ods and while these methods must be regarded 

 as means rather than as ends they neverthe- 

 less play a most important part of scientific 

 analysis. 



To most persons except the trained engi- 

 neer, biologist or statistician the principles of 

 analytic geometry which are the basis of most 

 graphic methods appear too difficult and in- 

 tricate as that they would be used for prac- 

 tical problems of every-day life. 



Mr. Haskell's book fills therefore a distinct 

 demand when it contributes to a clear under- 

 standing and wider application and recognition 

 of the graphic method. The treatment is 

 written from the standpoint of the practical 

 engineer who comes daily in contact with such 

 1 See " The Colors of Colloids, ' ' VII., J. Phys. 

 Chem., Vol. 23, pp. 365-414. 



pz-oblems which will lend themselves to the 

 application of this form of analysis. 



The 539 pages of the richly illustrated book 

 are divided into 18 chapters which go ex- 

 haustively into every phase and detail of the 

 possibilities and applications of graphic anal- 

 ysis. Special consideration is given to the 

 current engineering problems of to-day. One 

 whole chapter is devoted to the nomographic 

 or alignment chart. This subject is treated 

 in Chapter Vlil. and taken up again in 

 Chapter XVI., " Computation, arithmetical 

 and geometrical " which devotes some thirty 

 pages to this interesting subject. 



The author deserves much praise for faith- 

 fully collecting the manifold material on this 

 subject. On page 348 however I think it 

 would be worth while to mention the graphic 

 calculation of the fiolytropic curve based on 

 the equation 



(1 + tgp) = {1 + tga)". 



The lack of space prevents a longer expla- 

 nation but for the rapid design of isothermal 

 and adiabatic curves in connection with com- 

 bustion engine design, this method^ is ex- 

 tremely valuable on account of its accuracy, 

 rapidity and range covering all exponeuts 

 n^l.lO (isothermal) to 1.41 (adiabatic). 



Chapter VU. would have had room for the 

 smelting diagrams of Stead and Saklatwalla^ 

 and of Shepherd. 



Chapter XVII. is devoted to the graphic 

 methods of designing and estimating. The 

 civil engineer will find much of value and 

 interest here. I think however the chapter 

 could be extended to the advantage of the 

 mechanical engineer and his problems. 



The wealth of references relating to the 

 graphic methods which are given at the end 

 of each chapter and which have been collected 

 by Mr. Haskell make the book valuable as a 

 source of information, in short the author has 

 responded to a vital demand for a practical 

 book, " How to make and use graphic charts." 

 The practical man will find much material 

 ready for use and easily understandable and 



1 E. Braiier, Z. d. v. d., I., 1885, p. 433. 



2 Journal of the Iron and Steel Institute, 1908, 

 No. 11, p. 92. 



