144 Scientific Intelligence. 
be of high value to the artist, from one who has himself the great 
advantage of a practical knowledge of both drawing and painting. 
The book is largely made up of the results of the author’s own 
investigations, which give it a character a. its own; and it con- 
tains a large number of original Spear tio 
9. Color-blindness: its da gers and its eke by B. Joy 
Jerrries, A.M., M.D. 312 pp. 8vo. Boston, 1879. Hough 
Osgood & Co.).—The subject of Color-blindness is one of not 
only very general interest, but ofa high degree of practical. 
rtance, since many accidents on re and sea have resulted 
tions, and the eats ‘a are  ontained in this volume. It contains 
also a Hachaddin of the whole subject, with particular instructions 
in regard to the use of Holmgren’s method of testing for color- 
blindness. In his general eh ae Dr. Jeffries states that :— 
one male in twenty ive is color-blind in a greater or less degree, 
though he may be self unconscious of the defect ; moreover, 
though sometimes cau diasll temporarily or permanen ntly by disease 
or injury, it is largely hereditary, and in that case 1s incurable, 
recommends that rigid and uniform proof of soundness 
of vision should be required of every employé in the railway or 
rvice. 
0. Friction and Lubrication: determinations of the laws and 
coficients of friction by new methods and with new apparatus ; 
R, H. Tuurston, A.M., C.E. 212 pp. 8vo. New York, 1879. 
determination of the laws and coefficients of friction, The wor 
—, be of much value to the mechanical engineer. 
a. Apparate fir popes caine: gage Schule und 
Deracie g, gesammelt von M. Ta. EpEtmann Lieferung, 96 
pp- aR “Stuttgart, 1879 (Meyer & Zeller’s Verlag). —This work 
is to be complete in three parts, of which the first is now issued. 
It contains descriptions of the newest and most a appa 
ratus, designed either for instruction in the lecture room, or for 
actual scientific investigations. The scope of the work is a wide 
one, and it will be found useful by physicists, chemists, physiolo- 
astronomers, and those working in a ah ot _ hapa of 
science. The cay ae are full and precise any cases 
are accompani - illustrations hich - - increase 
the value of af the work. ae . i m : 
