6 NA TOFD: 
[NOVEMBER 5, 1903 
Solar and Magnetic Disturbances. 
Tue Kew photographic curves showed appreciable mag- 
netic disturbances of a normal type on the evening of 
October 30 and early morning of October 31, but the first 
distinct precursor of the magnetic storm was an_ ex- 
ceptionally sudden movement at about 6h. 3m. a.m. on 
October 31, shown alike in the declination, horizontal force 
and vertical force curves. This movement was largest in 
the horizontal force, where there was a sudden increase of 
about 60 y (1 y=1X10-° C.G.S. unit). In the declination 
there was a simultaneous movement of about 7! to the 
west, apparently preceded by a very tiny movement to the 
east, lasting too short a time to be distinctly shown. The 
first large movements commenced about 6.45 a.m., when 
there was a movement of the declination needle to the west 
through about 34’, and a diminution of 240 y in the hori- 
zontal force. The storm was most violent between 10 a.m. 
and 7 p.m. on October 31, but there was a large amount 
of disturbance until 3 or 4 a.m. on November 1. 
The -traces from the Kew magnetographs—declination, 
horizontal force and vertical force alike—went off the sheet 
repeatedly, so that the full extent of the disturbance cannot 
be derived from them. A declination magnetograph, how- 
ever, of lesser sensitiveness recorded apparently the com- 
plete movement, and showed a range of about 2° 12/. 
Between 1 and 7 p.m. there were at least twenty to and 
fro oscillations of the declination needle—each occurring 
in but a few minutes of time—the amplitude of which ex- 
ceeded 20’. In addition to these there was a very large 
number of smaller oscillations. At times these followed 
one another so rapidly that they can hardly be seen apart 
on the photographic sheet. In the horizontal force there 
were also very numerous oscillations. The general tendency 
from 7 a.m. to 10.30 a.m. was towards a reduction of the 
force. From 10.30 a.m. to 1 p.m. the oscillations were 
about a value not far from the normal. At about 1 p-m. 
there commenced a rapid rise, which in twenty minutes 
amounted to about 690 y, the curve going off the sheet. 
During the next two and a half hours the trace was often 
off the sheet. Between 3.50 and 5.10 p-m. the trace crossed 
the sheet from edge to edge, representing a change of about 
75° Y, or somewhat more than one twenty-fifth of the value 
of the whole horizontal force. The vertical force disturb- 
ance was small at first, and did not become really large 
until nearly noon on October 31. From noon to 4 p.m. 
there were numerous large oscillations, the curve going off 
the sheet repeatedly on one side. At about 1.40 p.m. there 
was an oscillation where, in the course of five or six minutes, 
there was a decrease and increase of more than 350 y- The 
trace remained off the sheet from about 3.30 to 5 p-m. 
Between 5.10 and 5.50 p.m. the force diminished about 
450 y- 
The storm is much the most notable recorded at Kew 
since February 13-14, 1892. CHARLES CHREE. 
National - Physical Laboratory, Richmond, Surrey, 
November 3. 
In connection with the magnetic storm of Saturday last, 
October 31, it may be of interest to record that observations 
made between to and 11 a.m. on that day by Prof. Callendar 
and myself showed a violent distortion and reversal of the 
C line of hydrogen in the neighbourhood of the great sun- 
spot group, which was then a little past the central 
meridian. A notable feature was the apparent detachment 
of a portion of the dark C line, the separated part present- 
ing the appearance of a cloudy patch, displaced towards 
the violet by about three tenth-metres. The observations 
were unfortunately interrupted by clouds. 
A reversal of the C line over the same spot had been 
observed on the two preceding days, but though on these 
occasions the bright line was more brilliant than on October 
31. there was much less distortion of the dark line. 
A. Fow er. 
Royal College of Science, South Kensington, November Be 
Dr. Shaw’s Address at the British Association, 
I HAVE received the following letter from Sir Arthur 
Mitchell, K.C.B., who has been for long closely identified 
with the Scottish Meteorological Society, both as a scien- 
NO. 1775, VOL. 69] 
tific worker and as an administrator, and who was one 
of the founders of the Ben Nevis Observatory, and I send it 
to you as it expresses what I am sure must have been the 
feeling of meteorologists on reading Dr, Shaw’s otherwise 
admirable and inspiring address on methods of meteor- 
ological investigation. 
34 Drummond Place, 
Edinburgh, 
October 15. 
Dear Mr. Omond,— 
Dr. Shaw's address to the subsection of astronomy and 
meteorology of the British Association in September last, 
by its appearance in Nature of September 17 has quickly 
and effectively reached the whole scientific world, and it is 
misleading in important directions, quite unintentionally, I 
believe. 
The absence of all reference to the meteorological work 
done by Buchan, Stevenson, Aitken, Buchanan, Murray, 
yourself and others will probably receive an interpretation 
which I hope is erroneous, for I cannot think that Dr. 
Shaw would designedly belittle the valuable work these men 
have done, which is recognised as being of a high character 
all over the world. 
But it seems to me more remarkable that Dr. Shaw 
should have made no special reference to the work of the 
Ben Nevis Observatories. In that work a very great, costly 
and laborious effort has been made to advance meteorology 
and to add to knowledge, and this has been done mainly 
through private enterprise, under the guidance of the fore- 
most scientific men of our time, including Kelvin, Tait, 
Buchan, Murray, Copeland, Aitken, Buchanan, Stevenson, 
and many others. The discussion of the outcome of this 
great experiment in connection with the physics of the 
atmosphere has only recently begun. It cannot be quickly 
finished, much time by many experts must be given to it, 
and it cannot fail to cost a large amount of money. 
My special object in writing to you is to suggest that, as 
honorary secretary of the Ben Nevis directors, you should 
in some way supply what I regard as an incompleteness 
in Dr. Shaw’s address by briefly stating how the work of 
the Ben Nevis Observatories now stands, and what prospects 
there are of its yielding further important additions to 
knowledge. 
Very faithfully yours, 
ArtHuR MITCHELL. 
In accordance with Sir Arthur’s suggestion I beg to make 
the following statement explanatory of the present position 
of the Ben Nevis Observatories, and to note briefly the work 
carried on at and in connection with these observatories. 
When the observatory on Ben Nevis was opened twenty 
years ago very little was known about the condition of the 
atmosphere above a few hundred feet height over the 
British Islands. The first object aimed at was to deter- 
mine the meteorological constants for that position, and 
the relations of the air there to that at sea-level in the 
neighbourhood. This latter part of the work has only been 
adequately carried out since the establishment of the Fort 
William Observatory in 1890. The observations down to 
the end of 1892 have been published in two volumes of the 
Transactions of the Royal Society of Edinburgh (Nos. 34 
and 42). The first of these was printed at the expense of 
the Royal Society of Edinburgh, and the second at the 
joint cost of the Royal Societies of London and Edinburgh. 
Another volume is in the press, and will be issued shortly. 
The constants referred to are :—(1) The average value 
at each hour of the day for each month of the year of 
barometric pressure, temperature of the air, humidity, rain- 
fall, direction and force of wind, amount of cloud and sun- 
shine on Ben Nevis. (2) The relation of each of these to 
the corresponding sea-level values at Fort William. 
Immediately arising from these average values is the 
question of the changes induced on them, especially on the 
second series, by different conditions of weather—that is, 
the determination of the vertical gradients of pressure, 
temperature, &c., under varying atmospheric conditions. 
This discussion has been partly carried out, and the more 
important results arrived at are summarised in papers 
appended to the two volumes of observations. 
One of the most interesting practical aspects of the Ben 
Nevis records is their application to the reduction of baro- 
metric readings to sea-level, a subject which is at present 
engaging great attention in this country, in the United 
