APRIL 15, 1915] 
NATURE 
185 

distant from 7» Serpentis, which star is further to the 
westward. 
THE CHROMOSPHERIC SPECTRUM WITHOUT AN ECLIPSE. 
—In the March number of the Proceedings of the 
U.S. National Academy of Sciences, W. S. Adams and | 
Cora G. Burwell describe briefly the results of an in- 
vestigation of the flash spectrum without an eclipse in 
the region A 4800 and A 6600. The full paper will soon 
be published as No. 95 of the Contributions from the 
Mount Wilson Observatory. In the first place, it is 
interesting to record that the total number of lines | 
measured upon the negatives taken without an eclipse | 
is greater than that obtained from eclipse negatives. 
Thus Mitchell’s beautiful chromospheric spectrum of 
1905 showed gor lines, while those here measured num- 
ber 1027 lines. It is further pointed out that in the 
photographs taken without an eclipse the wave-lengths 
of the bright lines have been determined with reference 
to the dark lines at the limb. A comparison of 512 
lines shows that the difference between the wave- 
lengths of the bright lines andthe darlx lines at the 
limb gives a value —o'oo2z2 Angstrom. The _pre- 
ponderance of the negative sign in the case of the 
individual elements makes it fairly probable that this 
quantity may be regarded as real. Reference is made 
also to the marked gain in accuracy for the Mount 
Wilson results, attributed notably to the greater linear 
scale of the photographs. Some peculiar charac- 
teristics of the dark line spectrum of the sun’s limb as 
seen on the photographs of the flash spectrum are 
briefly decribed, and the identification of the elements 
to which these lines belong is suggested as a research 
of decided interest. 
Tue Roration or Nesuta&.—Prof. Percival Lowell 
has forwarded two very interesting photographs of the 
spectra of nebule taken by Dr. V. M. Slipher, both 
of which are briefly described by the latter. The first 
is the spectrum of Virgo nebula, N.G.C. 4594, taken 
in April, 1913, with an exposure of 30 hours, together 
with comparison spectra of vanadium and iron. It 
was from this photograph and two others, also taken 
in the same year, all of which showed the nebula lines 
inclined, that the first direct evidence that nebulz 
rotate was secured. In the photograph sent the slit 
was placed east and west, and the rotation in the sense 
that brings the west side of the nebula towards the 
earth. In addition to their inclination the lines have 
a large displacement, which makes the solar band G 
nearly coincident with the iron line \ 4326, thus indi- 
cating a velocity of recession of 1100 kilometres. Dr. 
Slipher remarks that this was far the highest velocity 
then known, but ‘‘ further observations of nebula here 
have revealed others as high.’’ The second photo- 
graph is of the spectrum of the Crab nebula, N.G.C. 
1952, taken in February of the present year, with 
18 hours’ exposure, and similar comparison spectra. 
This is described as ‘‘the most remarkable nebula 
spectrum known.’’ Upon a rather strong continuous 
background are found bright lines typical of gaseous 
nebulz lines. Thus the lines AA 5007, 4959, 4861 (HB), 
4686, 4341 (Hy), seem to be present. The strange 
appearance of these bright lines is described as fol- 
lows :—‘t They seem to be split into doubles, best seen 
in A 5007 and A 4861 (the inside components of A 4959 
and A 5007 would be blended). The distance between 
the components changes with the position in the 
nebula. It reminds one of the Zeeman effects in a 
non-uniform magnetic field and implies the origin to | 
be within the atom. However, the maximum separa- 
tion is quite enormous—4o tenthmetres. A plausible 
explanation of the spectrum as velocity effects has not 
occurred to me as yet.” 
NO. 2372, VOL. 95| 

| finger movements. 
THE ‘ ScIENTIFIC AMERICAN”? AND AsTRONOMY.—The 
Paris Observatory and its work is the subject of an 
interesting article to the Scientific American (March 
13) by Prof. G. A. Hill, of the United States Naval 
Observatory. The author accompanies his text with 
two excellent reproductions showing the large transit 
circle and the eye end of the equatorial Coudé. The 
history of this famous institution is briefly sketched, 
and special reference made to the lunar photographs 
taken by MM. Loewy and Puiseux. In the issue of 
the same journal for March 20, Abbé Th. Moreux 
describes the planet Saturn, its ring system, and the 
satellites, and accompanies his remarks with a large 
number of reproductions from early and late drawings. 
Such articles popularly- written and finely illustrated 
render a great service in disseminating astronomical 
knowledge, and we hope to direct attention to similar 
contributions in future issues. 
EXPERIMENTAL STUDY OF THE 
MECHANISM OF WRITING. 
© 
recent years considerable advances have been 
made in the experimental study of the complex 
processes of reading and writing, mainly in the in- 
terests of a new experimental science, which is at 
present calling itself ‘‘experimental pedagogy,” and 
at recent meetings of the British Association the 
Educational Science Section has devoted a good deal 
of attention to such work. In the Proceedings of 
the Royal Society of Edinburgh a further contribution 
to the experimental analysis of the writing process is 
made in a paper by Mr. James Drever, on the 
analytical study of the mechanism of writing. 
Looked at from the outside, and regarded purely 
as a mechanical process, the writing act consists of 
certain movements and co-ordinations of movement of 
the fingers, hand, forearm, and shoulder. Of these 
the hand movements and the work of the fingers are 
the most important. By employing various pieces of 
comparatively simple apparatus it is possible to separ- 
ate hand and finger movements, as well as to isolate 
for observation and study both the pressure of the 
fingers in holding the writing instrument and also the 
pressure placed upon the writing point. 
To Prof. C. H. Judd, of Yale, we owe the original 
idea of a simple piece of apparatus which enables 
the experimenter to separate hand and finger move- 
ments. This apparatus consists essentially of an 
attachment for the fifth metacarpal, which carries a 
pencil or style for recording the movement of the 
hand. The original form of the apparatus was defec- 
tive in several respects, but a modified form described 
in the above-mentioned paper seems to eliminate 
most of these defects. By comparing the record of 
the hand movement with the actual writing we can 
determine the part played by finger movement. It 
should be noted, however, that there is one movement 
of the hand in writing which cannot be recorded in 
this way. That is the movement known as pronation 
—the movement round the axis of the wrist. 
Records taken with Judd’s apparatus yield several 
interesting results. Some writers use little, if 
any, finger movements, and most writers, when 
writing at maximum speed, and especially with the 
pencil, approximate to this type. Ordinarily, how- 
ever, in careful adult writing in this country, all the 
finer work in the formation of the lIetters is 
due to finger movement, and this to a greater extent 
in pen writing than in pencil writing. As a rule the 
writers themselves are quite unconscious of such 
In the writing of the child, who 

