'One should have seen M. Lescarbault,' says Moigno, 'so small, so simple, so modest, and so timid, in order to understand the emotion with which he was seized, when Leverrier, from his great height, and with that blunt intonation which he can command, thus addressed him: "It is then you, sir, who pretend to have observed the intra-mercurial planet, and who have committed the grave offence of keeping your observation secret for nine months. I warn you that I have come here with the intention of doing justice to your pretensions, and of demonstrating either that you have been dishonest or deceived. Tell me, then, unequivocally, what you have seen."' This singular address did not bring the interview, as one might have expected, to an abrupt end. The lamb, as the Abbé calls the doctor, trembling, stammered out an account of what he had seen. He explained how he had timed the passage of the black spot. 'Where is your chronometer?' asked Leverrier. 'It is this watch, the faithful companion of my professional journeys.' 'What! with that old watch, showing only minutes, dare you talk of estimating seconds. My suspicions are already too well confirmed.' 'Pardon me, I have a pendulum which beats seconds.' 'Show it me.' The doctor brings down a silk thread to which an ivory ball is attached. Fixing the upper end to a nail, he draws the ball a little from the vertical, counts the number of oscillations, and shows that his pendulum beats seconds; he explains also how his profession, requiring him to feel pulses and count pulsations, he has no difficulty in mentally keeping record of successive seconds.
Having been shown the telescope with which the observation was made, the record of the observation (on a piece of paper covered with grease and laudanum, and doing service as a marker in the 'Connaissance des Temps,' or French Nautical Almanac), Leverrier presently inquired if Lescarbault had attempted to deduce the planet's distance from the sun from the period of its transit. The doctor admitted that he had attempted this, but, being no mathematician, had failed to achieve success with the problem. He showed the rough draughts of his futile attempts at calculation on a board in his workshop, 'for,' said he naïvely, 'I am a joiner as well as an astronomer.'
The interview satisfied Leverrier that a new planet, travelling within the orbit of Mercury, had really been discovered. 'With a grace and dignity full of kindness,' says a contemporary narrative of these events,[55] 'he congratulated Lescarbault on the important discovery which he had made.' Anxious to obtain some mark of respect for the discoverer of Vulcan, Leverrier made inquiry concerning his private character, and learned from the village curé, the juge de paix, and other functionaries, that he was a skilful physician and a worthy man. With such high recommendations, M. Leverrier requested from M. Rouland, the Minister of Public Instruction, the decoration of the Legion of Honour for M. Lescarbault. The Minister, in a brief but interesting statement of his claim, communicated this request to the Emperor, who, by a decree dated January 25, conferred upon the village astronomer the honours so justly due to him. His professional brethren in Paris were equally solicitous to testify their regard; and MM. Felix Roubaud, Legrande, and Caffe, as delegates of the scientific press, proposed to the medical body, and to the scientific world in Paris, to invite Lescarbault to a banquet in the Hôtel du Louvre on January 18.
The announcement of the supposed discovery caused astronomers to re-examine records of former observations of black spots moving across the sun. Several such records existed, but they had gradually come to be regarded as of no real importance. Wolff of Zurich published a list of no fewer than twenty such observations made since 1762. Carrington added many other cases. Comparing together three of these observations, Wolff found that they would be satisfied by a planet having a period of revolution of 19 days, agreeing fairly with the period of rather more than 19-1⁄3 days inferred by Leverrier for Lescarbault's planet. But the entire set of observations of black spots require that there should be at least three new planets travelling between Mercury and the sun. Many observers also set themselves the task of searching for Vulcan, as the supposed new planet was called. They have continued fruitlessly to observe the sun for this purpose until the present time.
While the excitement over Lescarbault's discovery was at its height, another observer impugned not only the discovery but the honesty of the discoverer.
M. Liais, a French astronomer of considerable skill, formerly of the Paris Observatory, but at the time of Lescarbault's achievement in the service of the Brazilian Government, published a paper, 'Sur la Nouvelle Planète annoncée par M. Lescarbault,' in which he endeavoured to establish the four following points:—
First, the observation of Lescarbault was never made.
Secondly, Leverrier was mistaken in considering that a planet such as Vulcan might have escaped detection when off the sun's face.
Thirdly, that Vulcan would certainly have been seen during total solar eclipses, if the planet had a real objective existence.