1 
Fan. 5, 1882] 
NALORE 
217 
schools, and of which the object is to give the more 
common properties of determinants, illustrate the said 
properties copiously with examples of the second, third, 
and fourth orders, and give additional examples of the 
same kind for practice. The object is here on the whole 
well attained, there being more examples for the pupil 
than is usual. For a “ beginner’s text-book,’’ however, 
it is unquestionably long-drawn-out and expensive. A 
book (e.g. Délp’s, Bartl’s, &c.) with very much more 
matter and, to say the least, as good in quality, would be 
got in Germany for two shillings, and this costs five. 
The object of the author “to render an interesting and 
beautiful branch of mathematical analysis more accessible 
to junior students” is thus somewhat frustrated at the 
outset. 
EEIERS, LO LAE BDITOR 
[The Editor does not hold himself responsible for opinions expressed 
by his correspondents. Neither can he undertake to return, 
or to correspond with the writers of, rejected manuscripts. 
No notice is taken of anonymous communications. 
[The Editor urgently requests correspondents to keep thetr letters 
as short as possible. The pressuve on his space ts so great 
that it is impossible otherwise to ensure the appearance even 
of communications containing interesting and ncvel facts. | 
A Glimpse through the Corridors of Time 
THE eloquent and exceedingly interesting lecture by Prof. 
Ball, F.R.S., under the above title, reported in your journal, has 
brought to my mind a short, far too much forgotten paper by 
Immanuel Kant. With your permission I will give a few 
extracts from this paper, which cannot but be interesting to many 
of your readers. Kant became subsequently very celebrated in 
a sphere of human knowledge usually considered far removed 
from natural science, in consequence of which his papers relating 
to this science are now almost universally overlooked. Never- 
theless some of them contain extraordinary glimpses of truth a 
century or more in advance of this time, glimpses possible only 
to genius, 
‘The paper to which I wish more particulariy to draw attention 
was published in 1754, when Kant was thirty years of age. It 
will be found in the collected works edited by F. U. Schubert 
and K. Rosenkranz (Leipzig, Leopold Voss, 1839, vol. vi. p. 4). 
The paper relates to the question whether the length of day has 
altered, and through what cause. In this paper Kant states: 
** Tf the earth were a perfectly solid mass, without any liquid, 
the attractions of the sun and moon would not alter the rate of 
rotation round the axis. . , . If, however, the mass of a planet 
includes a considerable amount of liquid, the united attractions 
of the sun and moon, by moying this liquid, impress upon the 
earth a part of the vibrations thus produced. The earth is in 
this condition.” He then goes on to state that the moon pro- 
duces the greatest effect, and, the tide running round the earth 
in a direction opposed to that of rotation, ‘‘we have here a 
cause, on which we can count with certainty, incessantly reducing 
this rotation by as much as it may be capable of.” A little 
further on he says: ‘‘ When the earth steadily draws nearer and 
nearer to the end of its rotation, this period of change will be 
completed when its surface is, relatively to the moon, at rest ; 
z.e. when it rotates round its axis in the same time in which the 
moon revolves round it, and will, consequently, always show the 
same face to the moon. . . . If the earth were entirely fluid the 
attraction of the moon would very soon reduce its rotation to 
this minimum. Herein we at once see a cause why the moon 
always shows the same face to the earth. . . . From this we 
may conclude with certainty that when the moon was originally 
formed, and still fluid, the attraction of the earth must, in the 
manner above described have reduced the speed of rotation, 
which then in all probability was greater, to the present measured 
limit.” I have given only a few short abstracts, and I have no 
doubt that mathematicians may find many faults in the paper, 
but it is nevertheless clear that Kant had recognised the influence 
of tidal action, both on the earth and on the moon, and has 
given a glimpse through the corridors of time a century earlier 
than any of the authorities mentioned by Prof. Ball. 
After Kant it was, I believe, R. T. Mayer, of Heilbron, who, 
long before Prof. Helmholtz drew attention to the influence 
exerted by the tidal wave on the rotation of the earth. 
Westminster Hospital, December 5, 1881 A. Duprs 
Dante and the Southern Cross 
I HAD supposed the query—in reply to which I ventured to 
offer the very brief note which was printed in Nature (vol. 
XXV. Pp. 173) —to have proceeded from some English reader, un- 
acquainted with the various solutions of the difficulty involved 
in the question, which have been suggested, and who might have 
been satisfied with a reference to such a discussion of the matter 
as that in the ‘‘Cosmos,” by a critic in whom were united all 
the needful qualifications to a degree which can hardly be looked 
for elsewhere. 
Dr. Wilks appears to bave written with a similar impression in 
referring the querist to the commentary of the late distinguished 
Dantophilist, Dr. H. C. Barlow, whose fervid belief in the extent 
of Dante’s knowledge (‘‘ ottimo Astronomo, summo Teologo”’) 
could not be exceeded by the most ardent patriotism, and was 
never qualified by the judicious reservation which Signor N. 
Perini admits. What I venture to add, refers to the notes 
which have appeared, rather than the original query as I under- 
stood it. 
For a solution of the apparent paradox in Humboldt’s retain- 
ing the old view of the sense of ‘‘ prima gente” while accepting 
—not Galle’s ‘‘ opinion,” but—the result of his computations as 
to the visibility of the stars of the Southern Cross to the earlier 
inhabitants of Europe, I would refer Signor N. Perini to the 
earlier and much fuller development of Humboldt’s views, con- 
tained in the last twenty pages or so of vol. iv. of the Zxamer 
Critique de 1 Histoire de la Geographie Moderne, where, at the 
same time, will be found a great deal of valuable and suggestive 
information relative to the Arabian celestial globe theory, and 
also to the probability (the words ‘‘non viste mai; . . ”’ not- 
withstanding) of Dante having derived some knowledge of the 
constellations of the southern hemisphere from the description of 
“Les voyageurs pisans ou yénitiens qui visitaient l’Egypte, 
VArabie et la Perse.” But I would at the same time urge that 
the whole of what is said in the ‘‘ Kosmos” on the subject of 
the Southern Cross is not intended to be applied to the Dante 
question, but to the larger one of the progress of oceanic discovery, 
and that it was in connection with this larger topic that Hum- 
boldt availed himself of Dr. Galle’s computations. Dr, Barlow 
appears to have been misled by failing to notice this distinction 
in his enthusiastic letter to the Athen@um (September 1860) of 
which the article quoted by Dr. Wilks from the volume of 
“*Contributions to the Study of the Divina Commedia” is a 
condensation. 
Count St. Roberts’s essay, to which Signor N. Perini refers, 
is probably little known, and not easily obtained, in England ; 
but we may conjecture that its object was to argue against the 
supposition of the element of ecclesiastical mysticism—hateful 
to modern Italian liberalism—as entering into the Divina Com- 
media and affecting its imagery and modelling. If the essay 
had thrown any néw light on the subject of the query, we may 
conclude Signor N. Perini would have imparted it to us. How- 
ever, I believe that everything that can be found to throw light 
on this interesting question has been adduced and weighed with 
the dispassionate calmness of a master mind, as it is set forth 
with candour and perspicuity in the exhaustive discussions to 
which I have referred. In conclusion may I remark on the 
importance, in such correspondence as we have been engaged in, 
of quoting the original words of an author—with or without 
translation, as may be thought proper. In the quotation, as 
from ‘‘ Cosmos,” by Dr. Barlow, given by Dr. Wilks and the 
passage is re-quoted by Signor Perini—nonsense is made of a 
sentence by *‘da” being rendered ‘‘ since,” instead of ‘‘ where- 
as.” Jn the sare translation ‘‘ mit vieler Orientalischen Rei- 
senden aus Pisa” isimproved into ‘ with many /earned Oriental 
travellers of Pisa.” Such changes might sensibly affect any 
argument founded on the passages. For the same reason I 
would have preferred heading this correspondence ‘‘ Dante and 
the quattro stelle.” J. J. WALKER 
University Hall, December 31 
A Pet Baboon 
I KNow not if the inclosed account, written by a friend of 
mine now resident at Zanzibar, for whuse accuracy and trathful- 
ness I can answer, is worthy of a place in your columns. 
JuLIA WEDGWwoop 
“You ask after my quaint little pet baboon, and I really must 
give you the history of her end. She grew and she grew till 
