le ee 
JuLy 6, 1899] 
aver te AE 
235 
extreme exactitude of cranial measurements, especially when 
based, for example, on the cephalic index only, has often led to 
creating imaginary races among a given people. 
These and other wholesome warnings are uttered by O. 
Hovorka Edler von Zderas in the Cetralblatt fiir Anthropologie, 
iii. p. 289, who also points out that there is no need to calculate 
indices to the first or second decimal, and he also states that in 
the analysis of a people one should not take account of differ- 
ences of Jess than ten units in the index. 
As all investigators are well aware, the cephalic index gives 
no information upon the real form of the skull; this has been 
well emphasised by Sergi, who has sought to establish a more 
rational system of skull nomenclature. M. L. Laloy supports 
(2 Anthropologie, x. p. 105) Hovorka’s general contention, and 
refers to the clever visual analysis of the inhabitants of Bretagne 
by Dr. P. Topinard, which was published in the Jowrnad of the 
Anthropological Institute (1897, xxviii. p. 99). In the last 
number of the Journal (new series, i. p. 329) Dr. Topinard 
gives the results of the trip which he made to Cornwall last year 
in order to compare the anthropological types there with those 
he had previously ascertained in Bretagne, But in our own 
country Dr. J. Beddoe has long adopted a similar method of 
investigation, and his acute and trained powers of observation 
have thrown a flood of light on the problems of the races of 
Britain. The methods of the doyex of British anthropologists 
are those of the field naturalist, and there are many who realise 
that what is generally knownas ‘‘ natural history,” is as integral 
a part of biology as is the most refined 
laboratory technique. It is well to use 
one’s eyes for other purposes than for 
reading off scales on instruments. 
“ 
WAVE OR BILLOW CLOUDS. 
A: SERIES of cloud photographs 
taken by Mr. Alfred J. Henry, of 
the United States Weather Bureau, and 
contributed to the Mlonthly leather 
Review for February, is on several 
grounds specially instructive. It is too 
frequently the case that photographers 
content themselves with a single plate 
of a cloudy sky, which specially re- 
commends itself to their notice by the 
grouping and arrangement of the 
vaporous patches. But in this instance 
we have a succession of pictures of 
the same clouds, showing their varia- 
tion during the interval, and, more- 
| atmosphere. 
| regular arrangement of streaks presents the peculiarity of cover- 
similar weather conditions gave rise to a similar formation of 
clouds (also photographed) some two months later. 
This is all that instrumental registration and careful observ- 
ation can teach us, and possibly the slow onward movement of 
meteorological science is traceable to the strict adherence we 
have generally shown to the record of instrumental indications, 
rather than a confident appeal to theoretical research. But the 
study of such a cloud formation as that pictured here goes a 
step beyond the reading of instruments, and places in our hands 
a powerful means by which to investigate the motion of the 
It cannot have escaped general notice that this 
ing a considerable extent of the sky, almost simultaneously. On 
a comparatively clear sky these strips of cloud are suddenly 
| formed; and on the other hand, a sky uniformly covered can, 
in a very short space of time, break up and offer the appearance 
of these billow waves. This sudden origin of parallel streaks 
finds a complete analogy in the formation of waves over still 
water, when a slight wind agitates the surface, and it is seen to 
break into ripples over a considerable area. Von Helmholtz, 
working on this suggestion, has shown conclusively that these 
billow waves are due to the existence of air strata of different 
temperatures moving with different velocities, and are produced 
at the surfaces of separation of these various strata. Travellers 
in balloons have confirmed this theory from actual experiment, 
and have shown that at very various altitudes this peculiar 
formation is encountered. It may be that the billow clouds are 
over, taken in various azimuths at 
different stations, so that we get the 
same formation viewed from different 
standpoints. We regret that we can 
only reproduce one of the very admirable pictures that Prof. 
Henry has secured, It is the first of the series, and shows 
the typical arrangement of these clouds as they first arrested 
the attention of the observer. The altitude was probably 
that of the mean altocumulus level. Occurring as these 
clouds do at all possible heights above the surface, we are 
glad to netice that the term wave or billow, following the 
nomenclature of Helmholtz, is coming into use, since such a 
description more nearly expresses the character of the formation 
than do other terms which generally refer to the height alone. 
We have here in the cause of the formation of these clouds 
an instance of the advantage of theoretical investigation over 
simple observation. The readings of meteorological instru- 
ments explain nothing of the origin or behaviour of atmospheric 
waves. Prof. Henry has recorded for us, with the care that 
becomes a meteorologist, that the wind was blowing steadily 
from the north-west with a velocity of twelve miles an hour. 
Rain had ceased shortly before, and the temperature, which 
had fallen to 34° during the night, had risen at the time at 
which the photograph was taken (Sh. 25m. a.m.) to 36°. The 
direction of the parallel bands when first observed was ap- 
proximately east and west. Later they took up a position about 
N. 80° W. to S. 80° E. In an hour and a half the typical 
appearance of the billow wave had passed away, leaving the 
sky about half-covered with cirrus and cirro stratus. It is 
hot unimportant to note, however, that the occurrence of 
NO. 1549, VOL. 60] 
Wave or Billow Clouds. 
visible to us only under peculiar circumstances of moisture, but 
the wave motion in the invisible air is probably a most common 
phenomenon, and one that plays a large part in determining our 
weather conditions. 
THE PROPOSED MAGNETIC SURVEY OF 
THE UNITED STATES} 
THE present superintendent of the Coast and Geodetic 
Survey, Prof. Henry S$. Pritchett, perceiving the need 
of expansion in the magnetic work of the Survey, has brought 
about the formation of a separate division, known as the 
Division of Terrestrial Magnetism of the United States Coast 
and Geodetic Survey. The chief of this division is to be Dr. 
L. A. Bauer, who will have full control of all magnetic work, 
both in the field and in the office. 
The following preliminary outline will serve to give some 
indication of the character and scope of the work it is proposed 
to carry out with the enlarged opportunities. 
SECULAR VARIATION INVESTIGATIONS. 
The best evidence of the great demand for secular variation 
data is the fact that, thus far, eight editions of Schott’s secular 
variation paper have been successively issued by the Survey. 
1 Abridged from an advance proof of a paper. by Dr. L. A. Bauer in 
Terrestrial Magnetism. 
