270 
NA LORE 
[JANUARY 21, 1904 
take a single instance, Magdalen College spends more than 
5oocl. a year upon science professorships, fellowships and 
scholarships, or a seventh part of its net revenue, and of 
the last twelve fellowships it has awarded, six have been 
for research. Also it keeps up a very efficient private labor- 
atory, as, indeed, do five other colleges in the university. 
Oxford, January 9. H. M. VERNON. 
I tuInk that others may interpret the footnote as Mr. 
Vernon does, and it is therefore my intention to express 
myself more clearly when the address is republished. Surely 
all Oxford science men know what I meant to say, and if 
so, they must know how difficult it is to say it without 
making two or three particular references. It is evident 
from other parts of my address that I certainly did not 
mean that most of the Oxford science professors neglect 
research. On the contrary, I know that the majority of 
them perform their duties well, including duties as to re- 
search, and they do this in an antipathetic atmosphere 
such as science professors elsewhere know nothing of. If 
I had the inclination to punish a scientific man and the 
power, I would appoint him to an Oxford science professor- 
ship. 
Bonte of the most distinguished workers were listening 
to my address, and I know that they were not much annoyed 
when I expressed my opinion that, relatively to the position 
and wealth of Oxford, there is very little being done. We 
know the names of the Oxford men who are doing good 
research work in Oxford and elsewhere, and surely Mr. 
Vernon will not say that they form one-tenth of one per 
cent. of the number of living men who have been educated 
at Oxford. But I am not concerned with the easy standard 
which he is satisfied to apply. I was expressing what is a 
very general opinion, and oné that is certainly my own. 
Also in saying that Oxford fears and hates natural science 
I was expressing a very general opinion. It is ridiculed by 
Mr. Vernon, but he does not disprove it when he tells how 
Oxford trifles with science by the establishment of what are 
called science scholarships and fellowships and starved little 
laboratories. 
Public opinion has been burked for many years by this 
grotesque fooling. Add to this that the majority of the 
dons throw ridicule upon natural science studies and create 
an atmosphere in which it is nearly as difficult for a man 
to do scientific work as it is for a mouse to live in an 
atmosphere of carbonic acid. An earnest student of natural 
science swims in a sea of troubles, and the university 
authorities in their love for him ornament him with a mill- 
stone of compulsory Greek as neck ornament. Surely this is 
something worse than trifling; it is torture. The torture 
is not so exquisite as what is applied to natural science in 
schools which are under Oxford influence, but it serves its 
purpose. Joun PERRY. 
An Undescribed Rudimentary Gill-plume in the Cray- 
. fish. 
I sHoutp be glad if you would allow me to place on 
record the discovery, by Miss Margery Moseley (daughter of 
my old friend, the late Prof. H. N. Moseley, of Oxford), in 
specimens of the common cray-fish (Astacus fluviatilis), of 
a pair of minute gill-plumes (right and left), belonging 
apparently to the somite of the first pair of maxillipedes. 
Miss Moseley discovered these new minute gill-plumes, in- 
dependently, in the course of dissection of a series of 
*“ types’? in the department of comparative anatomy at 
Oxford. Finding no description of them in the text-books, 
and that they were not recognised or admitted by the 
authorities, she sent her notes and drawings on the subject 
to me. The discovery has been confirmed at my request by 
Dr. Calman, who is engaged in work on the Crustacea at 
the Natural History Museum, and he expresses his astonish- 
ment (in a letter to me) that so important and (when once 
noted) so obvious an organ can have been overlooked by 
the many students who have carefully examined the cray- 
fish since Huxley made it one of his ‘‘ types,’’ and pub- 
lished his researches on the gills of the astacoid Crustacea. 
The discovery is interesting, not only as a fact in the 
morphology of Crustacea, but as being a novelty in a sub- 
ject treated with special attention by so skilled an observer 
as Huxley, and minutely examined by thousands of students | 
NO. 1786, VOL. 69] 
and teachers during the last twenty years. Miss Moseley 
is preparing a description and drawings of the new gill- 
plumes for immediate publication. 
January 15. E. Ray LANKESTER. 
A Theory of the Cause of Atmospheric Electricity, 
Tue idea that the sun sends out a large amount of 
Becquerel rays has found considerable support in the scien- 
tific world, and has been used to explain a number of difficul- 
ties connected with cosmical physics, for example, the 
source of the sun’s energy and comets’ tails. ‘There is still 
another old standing difficulty which it appears to be able 
to solve, viz. the permanent maintenance of the electrical ~ 
field in the lower regions of the earth’s atmosphere. If we 
take for granted that the sun continually emits Becquerel 
rays consisting of positive and negative electrons, one would 
expect the following to be the consequence. Some of the 
electrons which reach the earth’s atmosphere will be 
absorbed—probably mainly by the water vapour and dust in 
the lower atmosphere—but according to Rutherford’s ex- 
periments more positive than negative; thus we may expect 
a greater number of negative electrons to reach the surface, 
a corresponding number of positive electrons being held back 
by the air. We at once see a cause for the positive charge 
of the air and the corresponding negative charge on the 
surface. If there were no “‘ dissipation ’’ the result would 
be a continual charging up of the atmosphere or an ever 
increasing potential gradient above the earth’s surface; but 
there is dissipation, and it counterbalances the tendency of 
the electrical field to increase. If we had a constant dissi- 
pation the result would be a maximum potential gradient 
in the daytime and a minimum in the night, for we must 
assume that more electrons reach the atmosphere in the 
day than in the night. But we know from Elster and 
Geitel’s measurements that the dissipation reaches a maxi- 
mum at midday; this will tend to reduce the maximum of 
potential gradient which would otherwise be reached about 
that time. This consideration agrees entirely with the fact, 
for Exner has described the daily variation of the potential 
gradient as ‘‘a simple daily period, distorted by a midday 
depression.’’ With the fairly constant daily period of the 
entrance of electrons into the atmosphere, the main deter- 
mining factor of the potential gradient will be the dissi- 
pation; thus we find a maximum potential gradient in the 
winter with a corresponding minimum dissipation. The 
relation between potential gradient and dissipation has been 
thoroughly investigated by Elster and Geitel, and they have 
found experimentally that © that which tends to reduce 
the dissipation tends to increase the potential gradient,”’ 
which is just what one would expect from the theory. This 
theory appears to me to be able to account for a great many 
more of the problems of atmospheric electricity, but the 
above will show the general idea. GEORGE SIMPSON. 
Projection of Imitation Spinthariscope Appearance. 
Witn reference to Sir Oliver Lodge’s letter in Nature of 
last week (p. 247), might I venture to say that I exhibited 
to a large audience the nature of the effect seen in a 
spinthariscope in a lecture which I gave on radio-activity 
at the Cavendish Laboratory last term? My plan is some- 
what similar to that suggested by one of Sir Oliver Lodge’s 
sons, and consists of two black discs rotating in opposite 
directions in a mechanical slide. The discs have a large 
number of transparent spots, so that whenever two of these 
coincide a flash is produced on the screen. The resultant 
effect is the same as that seen in the spinthariscope. The 
coincidences can be arranged so as to be most numerous 
near the centre. ifs, 28). 183; 
The Diminishing Size of the New Bishop’s Ring 
around the Sun. 
In addition to the notes recently given in NaturE by Prof. 
Forel, Mr. Rotch and Mr. Backhouse concerning the new 
Bishop’s Ring, I should like to direct attention to the 
steadily diminishing size of this ring. 
Mr. Backhouse says in vol. Ixvii. (p. 174) that the middle 
of this reddish ring in the summer of 1902 was 70° from 
the sun, but on December 21 it was only 40° from the sun. 
