bi a, 
April. 20. 1882 | 
- NATURE 
a ee mr ey ak 2h ess 
589 
preliminary arrangements, and to secure the success of 
the observations, has detailed one of his officers, at present 
stationed in Upper Egypt, to check the latitudes of the 
French map where the eclipse track crosses the Nile. 
Indeed, he has done more than this, and here comes the 
dark side of the picture so far as the observers are con- 
cerned. The eclipse happens in the very midst of the 
Khamseen season—that is the period of fifty days during 
which Lower Egypt is apt to be swept by a hot, exhaust- 
ing south-east wind, so dust-Iaden at times, that the sun 
is totally obscured. To escape the chances of this double 
eclipse, or at all events to minimise them, it will be 
necessary for the party to occupy high ground. Stone 
Pacha is, therefore, after consultation with our Consul- 
General in Egypt, prospecting for a camp and providing 
the necessary camp equipage, and although he himself 
will not, we believe, accompany the expedition, it is 
hoped that an officer of the Khedive’s household, himself 
an adept in astronomy, which he has studied at both 
Paris and Washington, will accompany the expedition as 
guide, counsellor, and friend, to assist in making the 
necessary arrangements with the various local authorities. 
So much, then, by way of preliminary. Now, a word on 
the instruments to be employed on this occasion. The 
resources of modern science place many means of attack 
in the hands of the astronomer. To get an idea of the 
physics of the solar atmosphere—what it looks like—to 
study, so to speak, its circulatory system, to which such 
special attention has been recently directed by the bold 
hypothesis of Dr. Siemens—to investigate its extent, and 
to determine the luminosity of its various regions, we 
have the astronomical telescope, and, better even than 
this for some purposes, the photoheliograph, that is an in- 
strument which enables us to obtain a photograph of all the 
sun’s surroundings visible during the eclipse. To deter- 
mine the chemical nature of the various regions, a ques- 
tion to which the keenest interest attaches at the present 
time, we have the spectroscope and the spectroscopic 
camera. By means of these instruments we can see what 
we cannot photograph, and photograph what we cannot 
see. In former eclipses, when the duration of totality has 
been longer, it has been possible to have different instru- 
ments mounted on different stands—there has been time 
to go from one to the other. But on this occasion such a 
course would be impossible. On one stand, therefore, we 
have four telescopes and two spectroscopes for eye ob- 
servation. On another stand we have a photoheliograph 
and spectroscopic camera for photographic registration. 
In the observing telescope two spectroscopes are so 
arranged that a movement of the eye through two inches 
is all that is required to pass from the greatest spectro- 
scopic dispersion (7 prisms of 60°) to the lowest (1 prism of 
60°) which can be conveniently employed during an eclipse. 
In this way it is hoped that the spectrum of the brightest 
and the spectrum of almost the dimmest part of the sun’s 
atmosphere can be observed, and for the first time in 
the history of eclipse observation, comparisons will be 
made with the solar spectrum itself, as a solar photo- 
graph taken before totality will be used as a scale. Much 
is hoped in the way of the photographic record, for since 
the last eclipse, the science of photography, following 
step by step the new views of molecular grouping sug- 
gested by the spectroscope, has provided us with silver 
salts, identical in chemical composition, but so different | 
physically that the red part of the solar spectrum can now 
be recorded as: satisfactorily as the blue part of the 
spectrum has ever been. Nor is this all. The rapidity 
with which an image can be impressed upon a sensitised 
Flate has been enormously increased, so that if all goes 
well, seconds now take the place of minutes, and more 
can be recorded in five seconds now than was possible in 
five minutes twenty years ago. 
We have no space in the present article to refer more 
precisely to the exact work which it is proposed to under- 
take, but this much may be said, that in eclipse, as in all 
other kinds of scientific observation, each attempt made 
to secure facts, instead of exhausting, increases the num- 
ber of points of interest to be investigated, and now- 
a-days we not only get this principle at work from eclipse 
to eclipse, but daily work in our laboratories and physical 
observatories suggests questions which can only be solved 
at such times. Hence eclipse observations are getting 
more and more connected with terrestrial chemistry and 
terrestrial physics by this intermingling of laboratory and 
eclipse work, and hence also the area of general interest 
will be increased as time goes on. 
In conclusion, we may state that the Government ex- 
pedition will consist of Mr. Norman Lockyer, F.R.S., 
and Dr. Schuster, F.R.S., with their assistants, Messrs. 
Lawrance and Woods. Capt. Abney, who was at first 
detailed for the duty, is prevented by ill-health from join- 
ing the expedition, but the photographic preparations 
have been made under his supervision. It may be added 
that Mr. William Black and Mr. J. Y. Buchanan, late of 
H.M.S. Challenger, will accompany the expedition, and 
it is hoped that Prof. Tacchini may join it at Cairo. The 
Katsar-i-Hind leaves Gravesend at 12.30 this day. 
THE EDINBURGH FISHERIES EXHIBITION 
HE International Fisheries Exhibition, which opened 
at Edinburgh on the 12th ult., and to which refer- 
ence has been already made in the columns of NATURE, 
is likely to prove a complete success—not only commer- 
cially, but also as an exhibition of much that is interest- 
ing in the natural history of our most valuable marine 
animals. 
The apparatus of capture takes up a large space 
inthe Waverley Market Hall, but no particular novelty 
in the way of fish-traps is shown; no artificial bait 
that would supersede the whelk or the mussel in 
the taking of cod has apparently been yet invented, 
although much required. Several models of im- 
proved rigs for fishing-boats are shown, but no im- 
provement has apparently been effected on the ponderous 
beam trawl, which ismuch complained of as a cumbrous 
instrument of fish capture. The exhibition is rich in 
specimens of stuffed fish contributed by various bodies 
of London anglers—but why not label them? It is not 
given to every visitor to a fishery exposition to know a 
jack from a perch. Some of the late Mr. Buckland’s 
finely modelled and correctly coloured fishes have been 
sent from Kensington—notably a model of a salmon 
captured in the Tay, which weighed, when taken, 72 lbs. 
Considering the importance of the salmon to Scotland 
as a rent-yielding fish, we had expected to find in the 
exhibition a methodical display of the progress of that 
mysterious disease which has of late overtaken that fish ; 
but, beyond a drawing of an afflicted salmon, we saw 
no other indication of the calamity. The display of 
oysters in progress of growth from the sfaz to the stage 
of reproduction, although not large, is exceedingly inte- 
resting. We pass over, in the meantime, the merely com- 
mercial exhibits, of which of course there are many, and 
shall only say of the piscicultural exhibition, that it 
merits at our hands a much fuller notice than we have 
room to bestow on itat present. A large number of maps, 
charts, books, and engravings, bearing on the natural 
history of our food-fishes and the economy of the fisheries, 
may be seen and consulted in the exhibition hall, whilst 
the illustrations of river pollution and purification attract 
a large degree of attention. Despite the deficiencies at 
which we have hinted, the exhibition is a valuable one, 
and, although not all at once, may lead to some new 
departures in the art of fishing, which may tend to aug- 
ment in a striking way the national commissariat. _ 
Among the exhibits which have attracted specia! at- 
tention are those sent by Mr. Oscar Dickson, of Gothen- 
