- 588 
= oe =F. & - <2 . 
sharp, and decisive, that to talk about an eclipse expe- 
dition in connection with it seems at first sight an ab- 
surdity, unless indeed we dignify by that name a jaunt 
in a penny steamer to Flamsteed’s famous hill. Thanks, 
however, to School Boards, boys’ clubs, and the like, 
the explanation will be apparent to everybody, and it 
is this. For, although on the 17th of next month the 
moon will come between us and the sun in such 
a way that part of the sun will be covered at Green- 
wich, which may be taken as a short title for the British 
Islands, the covering-up will not be total, and we shall 
have, therefore, only what is called a partial eclipse, 
hardly worth looking at, from the physical astro- 
nomers’ point of view. But a thin line can be drawn 
on the globe from the West Coast of Africa, through 
Egypt, Persia, Central Asia, and China, along which the 
moon will entirely cover the sun; and here, instead of a 
partial eclipse, we shall have a total one. 
This is one of the most important phenomena we can 
observe in the whole domain of physical astronomy, for 
a reason with which the readers of the Dazly News are 
already familiar, namely, that when the light of the 
bright interior nucleus of the sun which we usually see 
is prevented from illuminating our upper air, by the inter- 
position of the dark moon, the sun’s atmosphere, which 
we never see except at such times, is revealed in all its 
majesty, and invites study on the part of those who care 
for the mechanism of the universe in which their lot is 
cast. Now England is going to be represented at a 
point on this thin line, and therefore we must talk about 
an eclipse expedition in connection with this event; for 
while we write, the directors of the Peninsular and 
Oriental Company, who have ever shown the keenest 
‘anxiety to further the interests of science, are allowing 
the sacred bullion-room of the KXatsar-7-Hind, now 
getting up steam in the Royal Albert Docks, to be 
desecrated—as some will think, and they are welcome | 
—by packing-cases of ungainly shape containing such 
instruments and combinations of brass and iron as have 
never been built before. The expedition in question, 
which has been equipped and manned by the Science 
and Art Department and the Royal Society combined, at 
the suggestion of the Solar Physics Committee appointed 
by the Government, of course is intended to occupy a posi- 
tion along that thin line to which reference has already 
been made, and the most easily accessible point is one 
on the Nile, about roo miles north of Thebes, in lat. 
26 deg. 32 N.; the most easily accessible, but not perhaps 
quite the best, for the reason that on the Nile the totality 
—that is, the period during which the moon entirely 
covers the sun—will only last some 72 seconds, whereas 
at Teheran there will be 104 seconds of darkness, which 
it is to be hoped the Russian astronomers will utilise. 
Seventy-two seconds ! 
it is stated that the preparation of the new instrumental 
combinations and the investigation of the new methods 
to be employed have required three months’ solid work 
and thought, many will ask whether the game is worth 
the candle. The following considerations will show that it | 
was distinctly the duty of the men of science interested in 
these problems to endeavour to secure observations :—In 
the first place, it is a little discouraging to travel thousands 
of miles, and to go through all the preliminary work and 
anxiety connected with such an expedition, even if the 
eclipse is two or three minutes long, should the weather 
chances be 2 or 3 to I against success. On the Nile the 
weather chances—that is, the ordinary weather chances 
—are perfect, and there will be neither rain nor cloud. 
Secondly, the eclipse happens at the most critical time of 
the solar activity, thereby offering a most marked contrast 
to the last one observed in 1878. Then the sun was quite 
quiet. It was in a condition of almost unparalleled re- 
pose. Now, judging by what has happened, the sun 
should be in a condition of intense action, and from the 
The time is not long, and when | 
ON APUR EL 
ae [Abril 20, 1882 
recent rapid increase both of spots and prominences we 
know the prediction is being fulfilled. Thirdly, the remain- 
ing ten eclipses observable curing the present century— 
for, thanks to the diligence of Mr. Hind and others, we 
know almost to a minute when and where total eclipses 
will be visible until the year 1900—are not conveniently 
situated for observation, as the following list will show :— 
Next year one occurs with a maximum totality of 6 min., 
but the course is almost entirely over the Pacific Ocean. 
In the Marquesas, however, a duration of totality of 
2 min. 53 sec. may possibly be available. The next 
(1885) is accessible only in New Zealand, where the 
greatest totality will be almost 2 min. The longest 
eclipse, as before, falls on the Pacific. The eclipse of 
1886 has the longest totality in the century, but this falls 
over the Atlantic. In Grenada the totality will last 
34 min. On the African coast, south of Angola, the 
duration will be more than 43 min. The eclipse of 1887 
will be best observed in Russia, and 50 miles north of 
Moscow the totality will have a duration 2} min. On 
Lake Baikal the totality will last 3 min. 38 sec. The 
eclipse of 1889 will have at Angola a duration of about 3$ 
min.,and at Barbadoes of about 1} min., its greatest dura- 
tion being upon the East Atlantic. The next eclipse (1892) 
falls entirely on the South Pacific, and Antarctic Oceans, 
and must be lost, although the duration of totality ex- 
tends to more than 4min. On the whole, the most 
favourable eclipse for observation in the present century 
will be that of 1893, which enters the American continent 
near Coquimbo, where totality lasts nearly 3 min. ; then, 
crossing Brazil, it leaves the land near Ciara, where the 
duration will last 3?min. Crossing the Atlantic, it will 
again reach land near Bathurst, with a totality lasting 
about 4 min., and, crossing Central Africa, will leave the 
land finally near Khartoum. The eclipse of 1894 will 
occur almost, if not entirely, over the sea or the inac- 
cessible regions of Central Africa, but it may be total in 
the Seychelles. High latitudes are singled out for the 
path of the next eclipse (that of 1896), which, entering the 
Old World in Norway, passes across through Siberia to 
Japan. At Tana, in Finmark, a totality of about 1? min. 
may be observed. Hindostan will be the most favourable 
locality for observations of the eclipse of 1898, which will 
have a totality of a little more than 2 mins. 
It will be seen from the above list that although 
doubtless attempts will be made to secure observations of 
some of these eclipses, yet that in no case are we likely 
to get such a grand harvest of facts as have been secured 
during the last twenty years, notably during the eclipses 
of 1868 in India, 1869 United States, 1870 Mediterranean, 
1871 India, 1875 Siam, and 1878 United States again. 
This condition of things of course makes one hope 
that the coming seventy-two seconds will be utilised to 
their utmost, and in consequence of the warm co-opera- 
tion of the Egyptian Government, which has been 
appealed to by our Foreign Office, a serious attack is 
contemplated ; that is to say, in consequence of the local 
transport facilities afforded, large instruments, combining 
great solidity and fineness of adjustment, will replace the 
mountain artillery, so to speak, which alone can some- 
times be employed. The something like thirty cases into 
which each separate part of the two equatorial stands and 
telescopes to be used, with their spectroscopes and 
cameras, have been separately packed for convenience of 
carriage, will, on disembarkation at Suez, be placed ina 
special van which, on arrival at Cairo, will be ferried over 
the Nile, and so on to Siut, the most southerly railway 
station in Egypt. Another instance may be given of the 
keen interest which the Egyptian Government is taking 
in the matter. The shorter the totality, of course the 
nearer the exact central line of the eclipse must the ob- 
serving party be in order to secure the maximum of the 
calculated period of obscuration. Stone Pacha, chief of 
the staff, who is personally sparing no pains to make all 
