May 3, 1912] 
tion, a preliminary paper having been given at the 
last meeting. It includes a discussion of the 
measures of 110 spectra at seven different lati- 
tudes in the region \5,500-’5,700 and of 24 
spectra at the equator in the region A 4,200-A 4,300. 
The value of the rotational velocity at the equator 
is at 
5,600, v + v,= 2.021 = .003 km. = 14°.35, 
4,250, v + v,== 2.012 + .003 km. = 14°.29, 
where v + 1, is the linear and & the daily angular 
sidereal velocity. The law of equatorial accelera- 
tion or polar retardation follows the Faye form, 
having the following coefiicients: 
v + V,= (1.306 + .701 cos ¢) cos 
= 10°.84 + 3°.51 cos? ¢. 
A comparison of é for different determinations 
gives 
Reversing Layer 
Sun Spots | Facule | Flocculi aus 
1906-7 
Plas- 
kett 
14.81 | 14.53 | 14.63 | 14.35 
1908 
14.61 
Duner | Halm 
== 
14.40 | 14.62) 14.55 
Whether the smaller value obtained here is due to 
some systematic error or to a variation in the rate 
of rotation there is as yet insufficient evidence to 
determine. It may be pointed out that the Ottawa 
observations were obtained at sun-spot minimum 
and the major part of the others more towards 
maximum. 
A comparison of the residuals from lines of 
different elements in both regions indicates that 
any systematic deviations found, not greater ex- 
cept in one case than one third the average re- 
‘sidual, are due to some personal systematic effect 
in measurement and not to differences of the rota- 
tional velocity in different elements. 
The Moon’s Mean Parallax: F. E. Ross. 
The following values of the lunar parallax and 
related quantities are based upon the constants of 
the geoid obtained in 1909 by the U. 8. Coast and 
Geodetic Survey and upon Hinks’s value of the 
moon’s mass. 
Po = 3,422.526 + 07.012, 
A= 238,857.9 = 1.1 U. S. statute miles, 
S=1,079.93 = 1.04 miles, 
D= 0.6043 + .0003. 
P, is the constant of the sine parallax, A the mean 
distance, S the semi-diameter, and D the density 
SCIENCE 
709 
in terms of that of the earth. The correction to 
Hansen’s parallax is 
6H = + 07.45. 
Observations on the moon’s limb for the deter- 
mination of the parallax seem to be subject to 
large systematic errors. The results obtained by 
Olufsen, Henderson, Breen, Stone and Batterman 
lead to a value of 304 for the reciprocal of the 
earth’s flattening. This systematic error seems to 
be largely eliminated in the recent Greenwich- 
Cape series of observations on the lunar crater 
Moesting A. The value of the reciprocal of the 
flattening resulting from this series is 294.45. It 
is likely that considerable further improvement in 
the results by the observational method would be 
obtained by the adoption of a photographic method. 
The Secular Variations of the Elements of the 
Orbits of the Four Inner Planets: Eric Doo- 
LITTLE. 
This paper presents the results of a computation 
extending over upward of sixteen years which had 
for its object a new determination of the perturba- 
tions of the orbits of the inner planets based on 
the most accurate elements now obtainable. The 
method employed differed from that of Le Verrier 
and Newcomb in that it depended upon the evolu- 
tion of certain integral expressions instead of on 
the use of infinite series. Every possible device to 
insure accuracy was employed, the entire computa- 
tion being duplicated and all known test equations 
applied. The well-known discrepancies which exist 
between certain of the variations as derived from 
theory and their values as determined from ob- 
servation merely were fully confirmed. The fig- 
ures expressing the motions of the perihelion of 
Mercury, the node of Venus, the perihelion of 
Mars and the eccentricity of Mercury, respectively, 
are as follows. 
Newcomb New Computation Observation 
+ 109”.76 + 108.91 + 1187.24 
— 106”.00 — 106’.00 — 105’.40 
+ 148”.80 + 148.74 + 149”.55 
+ 47.24 + 47.235 + 37.36 
The Language of Meteorology: C. F. TALLMAN. 
(Introduced by W. J. Humphreys.) 
Scientific language is nowadays a somewhat 
neglected subject, and contemporary men of sci- 
ence show a reluctance to label their contributions 
to knowledge. 
In meteorology there is need not only of new 
terms, but of a much more general use of the 
terms already introduced and adapted to their 
