The second part, from the fascinating forgotten work Oddities: A Book of Unexplained Facts (Allan, London 1928) by R.T. Gould, on the non-existent planet Vulcan. The first part can be found here.
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| Vulcan Landscape (from Star Trek, the Motion Picture) |
It did not escape him that, supposing its mass to be in anything like the same proportion, Vulcan could not be held responsible for more than a small fraction of the disturbances observed to be taking place in Mercury's orbit.
He also calculated that Vulcan ought to be in transit on the sun's face on or about April 3rd and October 6th of every year, at which times it should, of course, be visible in the same manner as it had been to Lescarbault. He did not hold out much hope of its being seen at other times, since he computed that its lustre would be so feeble that it might easily remain unseen, even during a total eclipse of the sun.*
* Proctor has questioned this statement. By his calculations, Vulcan and Mercury, seen during eclipse at their greatest angular distance from the sun, would appear about equally bright.
The existence of Vulcan did not remain unchallenged for long. Shortly after Lescarbault had been decorated, news arrived from Brazil that another astronomer, Liais, whose observations exactly coincided, in point of time, with Lescarbault's, had been examining the same part of the sun with a more powerful telescope, and had seen no vestige of any such spot as Lescarbault had described. Animated, apparently, by the scientific equivalent of the old odium theologicum, Liais made no bones about imputing bad faith to his French confrère; and he took especial glee in pointing out that while Lescarbault had originally stated that he had watched the black spot enter on to the sun's disc, he had afterwards admitted to Leverrier that it was already on the sun when he first noticed it. A slanderous personal attack of this kind was quite unwarranted, and it is scarcely surprising that Lescarbault (who, whatever his defects as an observer†, was an honest man) did not reply to it.
† Long afterwards, early in 1891, he announced the discovery of a new and brilliant star–which proved to be Saturn!
For some years astronomers in general, stimulated by a circular issued from the Paris Observatory, kept a special watch upon the sun during the periods indicated by Leverrier, hoping to see Vulcan in transit. They were uniformly disappointed. On April 4, 1875, however, interest in the missing planet was revived by a telegram from Weber, a German astronomer stationed at Pechili, N.E. China, stating that he had observed a small round spot upon the sun, which had vanished a few hours later. As Leverrier had indicated April 3rd as one of the two possible dates for seeing Vulcan in transit, the coincidence was sufficiently striking.
Unfortunately, this spot had also been carefully examined at Madrid through a much more powerful telescope than Weber's, while it had been photographed at Greenwich. It proved to be an ordinary sun-spot, and not even quite round.
Another German astronomer, Wolfe, patiently collected details of nineteen observations, made during the period 1761–1865, of dark bodies, unlike sun-spots, having been seen on the sun's disc. It is, however, a significant fact that such appearances have almost invariably been reported by men who are almost unknown as observers, and never by any of the astronomers who, like Schwabe, Carrington, and Secchi, have devoted many years of their lives to making a daily scrutiny of the sun.
But although Leverrier's predicted transits of Vulcan had failed to materialize, it appeared in 1878 as if his views as to the impossibility of seeing Vulcan near the eclipsed sun had been over-cautious.
During the total eclipse of July 29, 1878, Professor Watson, already mentioned, who was well known both as a competent observer and a mathematician, made a careful search for intra-Mercurial planets, and believed himself to have discovered no less than two. Unfortunately, neither of these could be identified with Vulcan) and the question was further complicated by a report from Lewis Swift (another American observer) that he, too, had discovered an intra-Mercurial planet during the eclipse–which planet differed, as was apparent by its. position, both from Watson's pair and from Vulcan.
The matter is somewhat confused and difficult to follow. Briefly, the facts are these. Watson, at Rawlins, Wyoming, sweeping with his telescope over the space on the western side of the eclipsed sun, picked up a star which he took to be ζ Cancri, and then, on the way back towards the sun, observed another star, θ Cancri, with, close eastward of it, a much brighter body, which showed a perceptible disc.* It did not correspond in position with any known Star, and he took it to be an intra-Mercurial planet.
* The magnifying power used by Watson was only forty-live.
Subsequently, when checking the position of the pointers which he had used for recording the various star-positions (eclipses do not last long, and he had adopted this device to save time as much as possible), he became convinced that the star which he had taken to be ζ Cancri was itself a new body, about a degree eastward of that star, and presumably another intra-Mercurial planet.
Swift, a man of less standing than Watson and without (at that time) much astronomical experience, made his observations at Pike's Peak, Colorado. He observed two stars close together on the western side of the sun, of which one was apparently θ Cancri, and the other an intra-Mercurial planet. So far, his observation might be regarded as corroborating Watson's. Unfortunately, he did not determine which of his pair was θ Cancri, giving as his reason that both appeared equally bright; and it will be remembered that the new body seen by Watson close to θ Cancri was, most definitely, very much the brighter of the two.
It was found quite impossible to reconcile Watson's observations with Swift's, and the conclusion generally arrived at was that both observers had made several mistakes. It was considered that what Watson thought he mistook for ζ Cancri was, actually, that star: that his other intra-Mercurial planet was really θ Cancri: and that what he thought to be θ Cancri was a small 6th-magnitude star near it. By a similar process of substitution, it was inferred that what Swift took for θ Cancri and an adjacent intra-Mercurial planet were really 25 Cancri and a neighbouring 7th-magnitude star. These suppositions at least explain the various contradictions and discrepancies in the evidence. Fig. 19 shows the positions of the various bodies supposed to have been seen by Watson and Swift, and of the other stars referred to.
As already stated, whatever Watson and Swift saw it was not Vulcan. Since their time no one claims to have seen that planet, unless we except an American weather-prophet named Tice, the John Partridge of his day. During the 'eighties he evolved various astronomical theories in connection with his system of weather-prediction, and as these theories postulated, inter alia, the existence of Vulcan, he took the bold step of asserting that he had himself witnessed, on a certain day in September, a transit of that planet across the sun. Incidentally, be mentioned that he bad at first mistaken it for Mercury–a statement affording quite conclusive evidence as to the extent of his astronomical knowledge.* He pointed out that this transit was separated by an exact number of "Vulcanian years" (19 days 17 hours) from that seen by Lescarbault in March 1859. Unfortunately, be had not realized (although be was afterwards given every opportunity of doing so) that the interval between a spring, and an autumn transit of Vulcan ought (the Earth being then at the opposite side of her orbit) to be a whole number of "Vulcanian years" plus 9 days 20½ hours, and that what he was really claiming was that he had seen Vulcan through the sun.
* A transit of Mercury can only occur in May or November.
"The planet of romance," as the Abbé Moigno, one of its staunchest champions, once termed Vulcan, is now definitely regarded as "the planet of fiction". It is, perhaps, fitting that it should play a considerable part in a serial story "Planetoid 127" (penes me), written by Edgar Wallace, an author whom, although the fact is not definitely stated, I identify (by internal evidence) with the celebrated and prolific author-dramatist who gave us The Four Just Men, The Strange Countess, Sanders of the River, and many other novels whose number and circulation alike, I understand, have attained almost astronomical figures.
Professor Watson and his work figure in the story, which deals with a planet (hitherto undiscovered) of which the bodies supposed to have been seen by Watson are, in reality, the satellites. The planet is a duplicate, in all essential particulars, of our own earth, and revolves in exactly the same orbit at exactly the same speed. But, being situated diametrically opposite to us, it is perpetually obscured by the sun, and in consequence invisible! It is a great pity that Leverrier is no longer alive to discuss the mathematical consequences of this remarkable theory.
Our present telescopic resources do not permit of our making certain that there are no intra-Mercurial planets, but it is safe to say that if any such do exist they must be of the nature of asteroids (minor planets) and small at that. There is practically no doubt that Lescarbault's Vulcan cannot be one of them. It is, however, still doubtful what he actually saw.
In all probability it was a sun-spot. On the other hand, it must have been a very peculiar one, for he had already observed Mercury in transit, and therefore knew, at least, what a planet should look like when on the sun's disc. Another objection is the rapid motion of the body he observed. The sun-spots have an apparent motion due to that of the Earth, and they also are carried round by the sun's rotation at a speed which, curiously enough, is not the same for all parts of the sun's disc, but diminishes towards its poles. But the combined effect of both these motions would not account for more than a fraction of the rapid movement observed by Lescarbault.
On the other hand, if he actually saw an intra-Mercurial planet which has never been seen since, it must have been an exceedingly small one–from which two conclusions necessarily follow. In the first place, he must have been greatly deceived as to the apparent size of the body which he saw; and, secondly, if it was so small that it has not been seen since by the most powerful modern telescopes, it is almost incredible that Lescarbault, with his rather rudimentary telescopic equipment, could ever have seen it at all.
He is by no means the first observer to be misled by appearances. That has occurred to many quite eminent astronomers. The satellite of Venus is a case in point. During the seventeenth and eighteenth centuries it was observed by many astronomers of standing–by the elder Cassini in 1672 and 1686, by James Short in 1740, by Mayer in 1759, by Montbarron in 1764, by Montaigne in 1791, and at various other times by such men as Rodkier and Horrebow. All agreed that it appeared to be about a quarter as large as Venus (i.e. about two thousand miles in diameter). Yet it is quite certain that Venus has no satellite of this size–nor, so far as we know, has she any at all; from which it follows that she never can have had one, since if it had fallen on to her surface in the last century her aspect and orbit would have altered considerably; if it had fallen into the sun the resulting conflagration would be a commonplace of the astronomical textbooks; while if (which is quite impossible) it had fallen on to the earth it would have changed the face of every continent and might even, conceivably, have interfered with the publication of this book.
Some of the observations of this satellite may be explained by reflection in the object-glass, after the manner of the celebrated "companion of Procyon".* But Short observed it with two reflecting telescopes, employing with one of them three different eyepieces of varying powers.† It is quite impossible that he could have been so deceived–and he was a most careful observer.
* Otto Struve, of Pulkova, announced in 1873 that he had observed the dark companion of Procyon, whose existence had been suspected, on theoretical grounds, by Bessel (1844.) and Auwers (1861). He continued, for some years, to publish his observations of it. It was then discovered to be an optical illusion, due to a flaw in his objectglass, which was found to give similar spurious companions to Arcturus, Capella, and Regulus. † 60, 140, and 240. A reflecting telescope, of course, has no object-glass.
There can be little doubt, finally, that most, if not all, of the celebrated "canals" of Mars (first reported by Schiaparelli in 1877 and since observed in large numbers by the late Professor Lowell, of Flagstaff, Arizona, and others) are the product of imagination–not, of course, of deliberate deception. It is claimed that some have been photographed; but, as a well-known amateur astronomer) the late Dr. W. H. Maw, once remarked to me, "I've had a look at those photographs, and you want the eye of faith to see the canals on them". And it is worth noting that Barnard (Director of the Lick Observatory at the time when it possessed the largest telescope in the world), when asked whether he had made many observations of the canals, replied gravely that he regretted his telescope was too powerful to show them.
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