DECEMBER 15, 1899.] 
verbaux for 1892, p. 147). The report clearly 
points out that the difficulty in reducing the 
uncertainty in the measurement by this method 
to even the amount here attained, 2cg. per kg. 
(2 in 100 000), lies mainly in the impossibility of 
obtaining by linear measurements the true vol- 
ume of the cylinder. 
_ Although the liter was originally defined as 
having the volume of one cubic decimeter, yet 
the International Bureau, in 1880, deemed it 
best to adopt as a provisional re-definition, the 
volume of one kilogram of water at 4° C., 
its temperature of maximum density. This 
was necessary for three reasons; first, the adop- 
tion of the platinum kilogram instead of the 
mass of the cubic decimeter of water at 4° as 
the standard of mass ; second, the uncertainty 
as to the exact relation between the kilogram 
and the mass of the cubic decimeter of water ; 
and third, the fact that the great majority of 
scientific measurements of volume or capacity 
are made by weighing the volume of water dis- 
placed or contained by the space to be meas- 
ured. The scientific fraternity has unanimously 
adopted this practice. It is, therefore, pleasing 
to know from the above cited investigation that 
the discrepancy between the liter, as thus re- 
defined, and the cubic decimeter, is but 5 parts 
in 100,000, or one two-hundredth of one per 
cent. No revision of past work and no correc- 
tion of future results is, therefore, necessary 
where an error as large as one one-hundredth 
of one per cent. is unimportant; and this 
covers all engineering and the vast majority of 
scientific measurements. For work of an accu- 
racy not exceeding one one-hundredth of one 
per cent. we may assume the volume of one 
gram of water at 4° C. to be one cubic centi- 
meter, and the liter to be equal to the cubic 
decimeter. If the greatest possible accuracy is 
requisite, then we must add 5 parts in 100,000 
to the volume as thus computed. So corrected, 
the results will probably be trustworthy within 
2 parts in 100,000. 
The following data, computed from the above 
specific mass of water, and from the relation, 
1 inch = 2.54 000 5 centimeters, derived from 
the Bureau’s comparisons of yard and meter, 
are convenient : 
 SCIENC2. 
893 
One gram of water at 4° C. has a volume of 
1.00 005 cc. (+ 0.00 002 cc.). 
One cubic foot of water at 4°C. (389.2° Ft. 
has a mass of 62.4252 lbs. (+ 0.0012 lbs.). 
One cubic inch of water at 4° C. has a mass 
of 252.880 grains (+ 0.005 grains). 
S. W. HoLtman. 
BOOKS RECEIVED. 
System der Bakterein. W.M1GuLA. Jena, Fischer. 
1900. Pp. x+1068. 18 Plates. Mark 30. 
Practical Exercises in Elementary Meteorology. KR. DEC. 
WaRD. Boston, Ginn & Co. 1899. Pp. xiii-+ 
199. 
A Century of Science and other Essays. JOHN FISKE. 
Boston and New York, Houghton, Mifflin & Co. 
1899. Pp. vii+ 477. $2.00. 
SCIENTIFIC JOURNALS AND ARTICLES. 
Journal of Physical Chemistry, November. 
‘Thermal Coefficients,’ by J. E. Trevor; ‘On the 
Theorems of Robin and of Moutier,’ by Paul 
Saurel—both mathematical papers; ‘Hydrates in 
Solution,’ by Wilder D. Bancroft, a criticism of 
Nernst’s deduction that the percentage of hy- 
drated substance in a dilute solution is inde- 
pendent of the concentration. 
Bird Lore for December brings the first yol- 
ume toa close. Witmer Stone contributes an 
interesting description of ‘A Search for the 
Rudy Island (N. J.) Crow Roost,’ and W. E. 
Cram, ‘ Winter Bird Notes from Southern New 
Hampshire.’ A. A. Crolius tells ‘How the 
Central Park Chickadees were Tamed,’ and 
under the caption ‘The Surprising Contents of 
a Birch Stub,’ Frank M. Chapman describes a 
family of Chickadees, while P. B. Peabody fur- 
nishes two pictures of ‘ Richardson’s Owl,’ with 
accompanying text. The most important article, 
‘Humanizing the Birds,’ by Caroline G. Soule, 
is a timely protest against ascribing to the birds 
human qualities that they do not possess. 
There are numerous notes, reviews and reports 
from Audubon Societies. 
The Osprey for November commences with an 
article on the ‘ Breeding of the Fish Crow in 
Pennsylvania,’ by Frank L. Burns, and this is 
followed by ashort account of ‘ Dusky, or Some 
Traits of a Canary Bird,’ by Miriam Zieber. 
The main paper is a reprint of a very interesting 
