514 Curved Appearance of Comets’ Tails. (October, 
and cannot help us to discover. When, however, we find 
that a mere jumble of words, in which terms used in 
astronomy and in connection with physical science are 
mixed up together and put forward in a standard work 
intended for the guidance of the public as an explanation— 
when they have no real meaning as regards the facts they 
attempt to explain, we believe every true lover of science 
will agree with us that such proceedings should not only 
cease to be encouraged, but should be exposed and con- 
demned. 
We find also that the writers who thus attempt to explain 
by verbosity that which can only be solved by sound 
geometry almost invariably ignore facts. That the three 
angles of a plain triangle cannot be greater than 180° is to 
them of no consequence, and is to be overlooked if their 
not being greater interferes with some dogmatic theory. 
That these remarks are not uncalled for is, we believe, too 
well known to many really candid men of science. But 
that there should be no mistake on this point, we will now 
give one among many examples of the fact we wish to bring 
forward. 
We have pointed out in this article that a comet’s tail 
which coincided with the equino¢tial would appear as a 
straight line or as a curve, according to the position of the 
observer on earth. We also demonstrated that a comet’s 
tail which passed through the pole and was of considerable 
length would appear as a curve, and six hours afterwards as 
a straight line. The laws shown in these two cases hold 
good for the bending of comets’ tails in all other parts of 
the heavens, and the apparent curvature is due to a geometrical 
law and not to any physical cause. 
When then we find in a work of no less importance than 
the ‘‘ Encyclopedia Britannica,” under the article Astronomy, 
page 78, the following profound nonsense, put forward as an 
explanation of an effect due as we have demonstrated to a 
geometrical cause, it is evident how widely spread is this 
vicious system of explanation and how hollow and unsound 
are the scientific principles of those individuals who by 
such verbiage delude the ignorant and impose on the half 
scientific. 
The following is the explanation given:—‘‘ The slight 
curvature which is generally observed (in a comet’s tail) may 
be accounted for by combining the motion given to the 
vapours by the impulsion of the sun’s rays with the motion 
of the comet in its orbit; for the detached vapours are 
driven by the impact of the luminous particles beyond the 
