May 31, 1918] 



SCIENCE 



539 



reforming the world's calendar, by Honorable 

 J. M. C. Smith, of Michigan. 



It is gratifying to learn that the movement 

 for Calendar Reform is thus taking on definite 

 shape; and also that, from the writer's view- 

 point, the bill referred to embodies the feature 

 of dividing the year into thirteen lunar months, 

 thus assigning to the moon her rightful place 

 in detennining her share of time division in 

 the calendar. 



It would appear to he sufficiently obvious 

 without special mention, that it must be futile 

 for any individual government to undertake a 

 reform of the world's calendar without the co- 

 operation of the other principal civilized na- 

 tions; and that any legislation that may now 

 be projected along that line should be with the 

 object of securing such cooperation. 



It may be suggested also that the move- 

 ment might better be deferred until the pres- 

 ent world agitation shall have subsided. 



T. G. D.\BSEY 

 CELLULOID FOR COVER GLASSES 



To THE Editor of Science: War conditions 

 are causing many substitutes to be used, and 

 even I was forced to one by the scarcity of 

 cover glasses for microscopic work. I found 

 that sheet celluloid can very well be used in 

 place of the glass, the fiber thereof being prac- 

 tically negligible for beginning work. I take 

 sheet celluloid, cut strips about the width of 

 the slide, iron these strips flat (place the heated 

 iron over each part but do not rub, for rubbing 

 the iron causes other streaks), and then cut 

 the strip into small squares. In addition to 

 being unbreakable and so quite durable and 

 inexpensive, they can not scratch the lens by 

 the pupil running the objective into the cover- 

 slip, as beginners are prone to do with all cau- 

 tions about such dangers forewarning them. 

 Other science teachers may find this expedi- 

 ent worth trying. F. A. Varrelman 



Lowell High School, 

 Sax Fra.xcisco, Calif. 



AN ABSOLUTE SCALE FOR RECORDING 

 TEMPERATURE 



To THE Editor of Scienxe : I think the sug- 

 gestion of Dr. Marvin in a recent number of 



Science (15 March, 1918) with reference to the 

 adoption of an approximation to the absolute 

 scale of recording temperatures is a good one. 

 Two suggestions occur to my mind in trying 

 to devise an appropriate name for this scale. 

 As it is a combination of the Absolute and the 

 Centigrade the word " Abcent " composed of 

 the first syllable of each word seems to give a 

 fitting term. An alternative would be to call 

 it the " Thomson " scale, a name which would 

 signify that it closely resembles the Kelvin or 

 absolute scale but is not quite the same. As is 

 well known, Lord Kelvin's earlier name was 

 Sir William Thomson. J. Adams 



Central Experimental Farm, 

 Ottawa, Canada 



SCIENTIFIC BOOKS 



Calculus. By Herman W. March, Ph.D., As- 

 sistant Professor of Mathematics, University 

 of Wisconsin, and Henry C. Wolff, Ph.D., 

 Assistant Pr<3fessor of Mathematics, Univer- 

 sity of Wisconsin. McGraw-Hill Book Com- 

 pany, New York, 1917. Pp. xvi -f 360. 



Differential and Integral Calculus. By Clyde 

 E. Love, Ph.D., Assistant Professor of 

 Mathematics, University of Michigan. The 

 Macmillan Company, New York, 1916. Pp. 

 xviii + 343. 



Plane Trigonometry with Tables. By Eugene 

 Henry Barker, Head of the Department of 

 Mathematics, Polytechnic High School, Los 

 Angeles, California. P. Blakiston's Son 

 and Co., Philadelphia, 1917. Pp. 172. 



College Algelra. By Ernest Brown Skinner, 

 Assistant Professor of Mathematics, Univer- 

 sity of Wisconsin. The Macmillan Com- 

 pany, New York, 1917. Pp. vi + 263. 



Projective Geometry. By L. Wayland Dow- 

 ling, Ph.D., Associate Professor of Mathe- 

 matics, University of Wisconsin. McGraw- 

 Hill Book Company, New York, 1917. Pp. 

 xiii + 215. 



Elliptic Integrals. By IL\rris Hancock, Pro- 

 fessor of Mathematics in the University of 

 Cincinnati. John Wiley and Sons, New 

 York, 1917. Pp. 104. 



Of the making of many text-books of mathe- 

 matics for colleges and secondary schools there 



