SCIENTIFIC SUMMARY. 
419 
the companion has, so to speak, doubled the above extremity, and that con- 
sequently the orbit can be determined very approximately. Hitherto it was 
impossible, as the lamented Captain Jacobs remarked, to say how far the 
apparent ellipse extended in a northerly direction, and correspondence be- 
tween observation and calculation did not suffice to establish the correctness 
of a set of elements. Now, however, though even four or five additional 
years will enable us to improve the orbit,, especially as to the time of peri- 
astral passage, the results I have arrived at undoubtedly approximate pretty 
closely to the truth.” 
These results are, for the perspective orbit — 
Semiaxis major 17" 
Semiaxis minor 2"-8 
Greater maximum distance 23"-8 
Position angle for „ 210° 40 / 
Lesser maximum „ 10"*4 
These values result in the following elements for the real orbit : — 
Longitude of the periastre 38° 40 / Mean distance 20"T3 
Eccentricity -63944 Period 76-25 years 
Longitude of Rising Node 24° 18' Epoch of periastral passage 1874-2 
Inclination 81° 13' 
Position angle for distance 
Greater minimum „ 
Position angle for ,, 
Lesser minimum „ 
Position angle for „ 
18° 45' 
3"-98 
301° 45' 
1"-16 
115° 30' 
Spectrum of a Solar Prominence . — Professor Young, of America, has made 
a remarkable observation. On April 9, 1870, there was an exceedingly bright 
prominence on the south-west limb of the sun, near, but not over a large spot 
which was passing off. At the base of this prominence, which was shaped 
like a double ostrich plume, the 0 line was intensely brilliant, so that the 
slit could be opened to its whole width in studying the form of the pro- 
minence, but this line was not in the least distorted. On the other hand 
the E line, also very brilliant, was shattered all to pieces, so that at its base 
it was three or four times as wide as it ordinarily is, and several portions 
were entirely detached from the rest. This is a most perplexing result, and 
seems to throw doubt on the interpretation which has hitherto been given 
to the displacement of the solar spectral lines. As Professor Young remarks, 
u Since the C line was not similarly affected, it is hardly possible to attribute 
this breaking up of F to cyclonic motions in the gas from which the light 
emanates, and it becomes very difficult to imagine a cause that can thus 
disturb a single line of the spectrum itself.” “ Possibly,” he adds, but we 
must admit we can hardly conceive the possibility, u the appearance maybe 
the result of local absorptions acting upon a line greatly widened by increase 
of pressure or temperature.” In other words, as we understand him, Pro- 
fessor Young would imply that the bright F line was really undistorted, 
though widened, while distorted absorption lines belonging to some other 
element produced the appearance of shattering. But apart from the 
difficulty of assuming cyclonic motions in this other element, around a 
relatively quiescent hydrogen -core, we know of no elements having lines 
close by F strong enough to produce the observed result. The apparent 
dissociation of the F and C lines is a phenomenon of a very perplexing 
character. 
The Physical Condition of the Sun. — Dr. Zollner, whose pictures of solar 
prominences will be known to many of our readers, has written an interest- 
E U 9 . 
