Marcy 1, 1912] 
cloudless days alone were considered, since in 
practical work a knowledge of the moisture 
content is needed only upon such days. The 
data used pertain to Europe alone, but pre- 
sumably are fairly representative of condi- 
tions everywhere, since they cover the obser- 
vations of several years and were obtained at 
many different places. Though the amount 
and the distribution of the water vapor in the 
atmosphere varies greatly from day to day and 
from place to place, it is interesting to learn 
that there is a tendency toward a maximum 
of humidity just above one of the levels of 
maximum cloudiness, the cumulus level. 
While there were no clouds at this or any 
other level at the times of observation, the 
water vapor was relatively abundant there, 
and, though not dense enough to produce a 
cloud, was made manifest by the readings of 
the hygrometer. Among the conclusions 
stated by Professor Humphreys (Bulletin of 
the Mount Weather Observatory, Vol. 4, 
Part 3) are the following: 
The amount of water vapor per unit volume 
decreases with elevation in an approximate geo- 
metri¢ ratio, and the thickness of the water layer 
that would result from a condensation of all the 
water vapor in the atmosphere above any given 
level, whatever the season, so long as cloudless 
days are used, may be approximately expressed by 
the equation, d—=2w, in which d is the depth of 
the water layer in millimeters and w the weight 
in grams of the water vapor per cubic meter at the 
given level or place of observation. An alternate, 
and probably equally good expression, is, d= 2e, 
in which d, as before, is the depth of the water 
layer in millimeters, and e the partial pressure of 
the water vapor in millimeters of mercury. 
Professor J. Hann had previously con- 
eluded, from observations made upon all 
kinds of days, regardless of cloud, that 
d= 2.3e, or about 15 per cent. greater than 
the value now found for clear days. 
NEW BOOKS 5 
Amone the books which have recently ap- 
peared are: (1) “ Thermodynamik der Atmos- 
phire,” by Dr. Alfred Wegener. Leipzig, J. 
A. Barth, 1911. 8°. 331 pp: (2) ‘“ Aero- 
nautische Meteorologie,” Teil II., by Dr. 
SCIENCE 
345 
Franz Linke. Frankfurt a. M., F. B. Auf- 
farth, 1911. 8°. 126 pp. (3) “Climatic 
Control,” by L. ©. W. Bonacina. London, 
Adam and Charles Black, 1911. 8°. 167 pp. 
(4) “Studie iiber Licht und Luft des Hoch- 
gebirges,” by Dr. C. Dorno. Braunschweig, 
EF. Vieweg & Sohn, 1911. f°. 153 pp. 
(5) “Dynamic Meteorology and MHydrog- 
raphy,” Part II., Kinematics, by V. Bjerknes 
and different collaborators. | Washington, 
Carnegie Institution of Washington, 1911. 
4°. 175 pp. (6) “The Clouds and Fogs of 
San Francisco,” by Alexander McAdie. San 
Francisco, A. M. Robertson, 1912. 8°. 
106 pp. 
EXCESSIVE PRECIPITATION 
Durine the month of July last, Luzon, the 
largest of the Philippine Islands, was visited 
by three typhoons accompanied by rains which 
are among the heaviest on record anywhere 
upon the earth. The precipitation accompany- 
ing the first typhoon was greatest at Baguio, 
the summer capital and official health resort 
of the islands. The rainfall there, as regis- 
tered by an automatic gauge of standard de- 
sign, was as follows: 14th, 34.64 inches; 15th, 
28.88 inches; 16th, 16.73 inches; 17th, 7.89 
inches—a total of 88.14 inches in four days. 
(The mean annual rainfall for New York 
City is 45 inches.) The second storm was 
severest at Bolinao, where 26.69 inches of rain 
fell during July 20 to 27, inclusive. With the 
third typhoon, that of July 30 to August 2, 
inclusive, 23.80 inches fell at Candon, while 
Baguio received an additional 20.14 inches. 
Naturally the floods following these unpre- 
cedented downpours did enormous damage. 
The $2,000,000 military road stretching for 
52 miles over the mountains between Dagu- 
pan and Baguio was seriously damaged. It 
had previously been forecasted that this road, 
regarded as one of the engineering feats of 
the islands, would remain “until the Pyra- 
mids crumbled.” The rainfall at Baguio dur- 
ing the four consecutive days of the first 
storm has rarely been exceeded anywhere in 
recent times. The only records of greater 
amounts for a similar period are : (1) 101.84 
inches at Cherrapunji, India, June 12 to ‘15, 
