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Considered from a scientific point of view, some of the gravest errors into which the author has fallen are the suppositions, that the perihelia and nodes of the planetary orbits move uniformly, and that they can ever become exactly circular.
Those and they are many who vaguely think that science is something different from common-sense, and that any book is scientific which talks about perihelia and asymptotes and cetacea, will find their vague notions here well corroborated.
He proves, that as the planets make their revolutions in ellipses, and consequently being at a much greater distance one from the other in their Aphelia, and a little nearer in their Perihelia; the earth's velocity, for instance, ought to be greater when it is nearer Venus and Mars, because the fluid that carries it along, being then more pressed, ought to have a greater motion; and yet it is even then that the earth's motion is slower.
Crossing as they often do the paths of the planets in their progress to and from their perihelia, it cannot but be that they should now and then come in contact with one of these spheres. One, called Lexell's, did come athwart the satellites of Jupiter in 1769, and once again in 1779, so as to be deranged in its own course.
Ordinarily, comets are conspicuous at their perihelia, as being their shortest distances from the sun, which is the focus of their orbit, and inasmuch as a parabola is but an ellipse with its axis indefinitely produced, for some short portion of its pathway the orbit may be indifferently considered either one or the other; but in this particular case the professor was right in adopting the supposition of its being parabolic.
"Those minor planets all are known to rotate in a narrow zone between the orbits of Mars and Jupiter; in their perihelia they cannot approximate the sun as we have done; we shall not be classed with them." "Our lack of instruments," said the count, "is much to be deplored; it baffles our investigations in every way." "Ah, never mind! Keep up your courage, count!" said Servadac, cheerily.
The art has also been applied to the observation of comets at distances from their perihelia so great as to prevent their visual observation. Thus has Wolf, of Heidelburg, found upon old plates the position of comet 1905.v., as a star of the 15.5 magnitude, 783 days before the date of its discovery.
Professor Newton's inquiries into the tracks pursued by meteorites previous to their collisions with the earth tend to distinguish them, at least specifically, from shooting-stars. He found that nearly all had been travelling with a direct movement in orbits the perihelia of which lay in the outer half of the space separating the earth from the sun.
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