382 
errors in Dr. Tyndall’s popular works ; and to join the too thin 
ranks of those who, like Mr. Sedley Taylor, are not to be im- 
posed upon by a popular reputation—but venture to think for 
themselves and to give the public the benefit of the result. 
8. Opportunities for such public warning have never been 
wanting, but now they are so numerous that a long essay would 
be requisite to do justice to them all. 
In the meantime, as an example or two, I may call attention 
to the way in which Sir Charles Wheatstone, and (by implica- 
tion) Sir William Thomson, and others, some of whose splendid 
scientific labours have had the misfortune to become profitable 
in a pecuniary sense, are treated in Dr. Tyndall’s ‘* Lectures 
on Light,” just published. The contrast between the utter con- 
tempt for money shown by their censor, and the (implied) 
opposite which is condemned as unworthy of scientific men, is 
brought out with all the flow of word-painting and righteous in- 
dignation which Dr. Tyndall so abundantly possesses. Besides, 
the monstrous doctrine is inculcated that men who devote them- 
selves to practical applications are men incapable of original re- 
search, 
g. But, to conclude for the present, I would simply call atten- 
tion to the following passage, which comes from an author who 
in the same work treats of the relative merits of such giants as 
Young and Fresnel. What confidence can one have in the ac- 
curacy of any statement on a scientific matter made by the author 
of it? :— 
«¢ And here we may devote a moment to a question which has 
often been the subject of public discussion—whether, namely, 
a rainbow which spans a tranquil sheet of water is ever seen 
reflected in the water? Supposing you cut an arch out of paste- 
board, of the apparent width of the rainbow, and paint upon it 
the colours of the bow; such a painted arch, spanning still 
water, would, if not too distant, undoubtedly be seen reflected 
in the water. The coloured rays from such an arch would be 
emitted in all directions, those striking the water at the proper 
angle, and reflected to the eye, giving the image of the arch. 
But the rays effective in the rainbow are emitted only in the 
direction fixed by the angle of 41°. Those rays, therefore, 
which are scattered from the drops upon the water, do not carry 
along with them the necessary condition of parallelism ; and, 
hence, though the cloud on which the bow is painted may be 
reflected from the water, we can have no reflection of the bow 
itself.” —“ Lectures on Light,” p. 25. 
If Dr. Tyndall, with the assistance of his scientific advisers, 
fails to see the justice of my remark on this passage, perhaps 
you will permit me to make it the text of a little essay in a 
future number. 
T have all along said, and still say, that I cordially recognise 
the services of Dr. Tyndall in popularising certain parts of 
Science. But his readers must be cautioned against accepting 
as correct great parts of what he has written. It is granted to 
very few men to do this useful work without thereby losing 
their claim to scientific authority. Dr. Tyndall has, in fact, 
martyred his scientific authority by deservedly winning distinc- 
tion in the popular field. One learns too late that he cannot 
“make the best of both worlds.” 
I would request Dr. Tyndall for his own sake, not for mine, 
should he favour me witha reply, not to pick out one or two iso- 
lated passages of a letter, which absence from books may possibly 
have rendered slightly inaccurate—but to answer me, as he has 
not answered Forbes, in the full spirit and not in the partial 
letter. P. G. Tair 
St. Andrews, Aug. 20 
W. S.J. on Hegel 
I RESPECTFULLY request admission, into an early number of 
Narure, for an explanatory word or two, in reference to 
W. S. J.’s review of my poor book on Law, &c., in the valuable 
publication named, for July 24, 1873. 
W. S. J.’s very first sentence speaks of the said little book as 
containing ‘‘a discussion of Hegel's opinions concerning gravi- 
tation and the differential calculus.” In the first place, Hegel 
has nothing to say against either gravitation as a fact, or the dif- 
ferential calculus as an established method of indubitable scien- 
_ tific calculation ; he would only attempt to philosophise both by 
placing metaphysical principles under them. Now this is part 
of Newton’s own action, and he certainly would not object to 
any attempt, Hegel’s or other, in the same direction. In the 
second place, I discuss no opinion of Hegel in this reference : I 
only attempt to expose erroneous opinions of Hegel’s relative 
NATURE 
opinions, To this I strictly confine myself, and this goes much 
deeper than the reader may, at first, think. 
On Law, whatever is said by W. S. J., concerns only the old 
difficulty of Hegel’s dialectic ; and perhaps the italicising of this 
word, together with my own intellectual deficiences, may be 
respectfully offered in explanation of as much, W. S. J. here, 
then, is evidently misintelligent himself, and, accordingly, only 
speaks so as to induce misintelligence in others. Nevertheless, 
it is worth saying that the reader may or may not gain from the 
particularity of satire in W. S. J.’s hands—so keen is it that it 
cows, and, again, so kindly that it disconcerts. 
Mathematically, according to W.S. J., ‘‘the critical state- 
ment of the necessary outcome of Hegel’s philosophy,” reduces 
itself to this, that the principle in question is placed ‘‘in that in 
which the quantum has disappeared, and there remains the rela- 
tion only as qualitative relation of quantity.” W. S. J. has for 
this only the mildly-authoritative contempt of a duly-elevated 
position ; and when it is said ‘* What is called infinitely Zi7#/e is 
only qualitative, and is neither little nor great, nor quantitative 
at all,” he at once squelches all by an ‘‘on the contrary!” 
Now all this contemned matter comes directly, not from Hegel, 
but from Newton; for the former, ‘quoting from the latter, 
says :— 
‘These (N.’s increments and decrements) are not to be taken 
as particles of a definite magnitude (farticule finite). Such 
were not themselves moments, but magnitudes, generated out of 
moments ; what is to be understood, rather, is the principles or 
beginnings (elements) of finite magnitude :” that is, plainly, what 
is concerned lies “in that in which the quantum has disappeared 
as quantum, and there remains the relation only as qualitative 
relation of quantity.” 
What concerns comets is naively amusing. We have not had 
to wait in their regard (as W. S. J. seems to think) for the in- 
formation of ‘‘ Chambers’ Handbook.” The astronomers of 
the last century, as it appears, were able to speak better than 
even the ‘‘ Handbook.” Comets that return, they say, though 
after a great many years, travel in ellipses of enormous axes ; 
whereas those that do not retum may describe parabolas or 
hyperbolas. Such is the opinion of Science yet, though it may 
talk of many other explanations of non-return, as dissipation, in- 
terception, &c. This, I say, ishow Science looks yet; but W.S.J., 
for his part, is under the belief that Science has actually within 
its ken comets that (so to speak) vevo/ve in hyperbolas, as well as 
others that revolve in ellipses. (Positively such seems his idea. 
Now, Hegel is never once at fault here—in his own way, I 
mean ; for whether in ellipse, in parabola, or hyperbola, Hegel’s 
assignation of the moment of singularity to the comet is, on his 
own principles, justifiable. May not a non-returning comet, 
too, be attributed to that contingency which is, and must be, 
inherent in externality as externality? On the whole, it may be 
well for us all to let comets alone yet. Our greatest living au- 
thority can only philosophise them into stone-rattles which the 
sun (for his amusement ?) whirls about his head. 
One has only to consider these things and others the like—the 
exquisite little gibes, not forgotten, about a secret in two volumes 
and a secret in fifteen pages, &c.—to perceive that what we have 
here is only once again the blind rush of prejudice from its usual 
dark corner of relative ignorance—an ignorance which it will 
persist in, and not (through study) convert into the light of day. 
There is that approbative allusion to Mr. Smith, too; W. S. J. 
will yet be ashamed of that. 
On the whole, however, I hope I have not spoken disrespect- 
fully, for I cannot fancy who W. S.J. maybe. He talks of 
law and logic, and is possibly a lawyer ; he certainly has a pro- 
found contempt for “ Hegel and his satellite Stirling ;’ but were 
he (what his initials may indicate) ‘‘the eminent Jaggers” 
himself, I cannot, whateyer his power of fracfice, admire his 
capacity for principles. 
Edinburgh, July 28 J. HutTcHIson STIRLING 
Lakes with two Outfalls 
In Nature, Aug. 14, a paper under this heading concludes 
thus :—‘‘ Colonel George Greenwood, who is, I presume, the 
same as the former active correspondent about this subject, 
visited this lake (Lesjeskaugen) last summer, as appears from 
the entry of his name in the day books. I am not aware that he 
has since published any opinion, but the lake seems, so far as I 
can judge, to support his view of the matter.—W. Stanley 
Jevons.” I sent an account of my visit to Lesjeskaugen Lake 
[ Sept. 11, 1873 
a 
