HISTORY OF PHYSICAL ASTRONOMY.

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sufficient attention on the subject, may have been misled to some extentby this groundless clamour, we deem it not altogether out of place to sub-mit a few remarks here in relation to it. We have not indeed the slightestdoubt that if a diligent search of the heavens had been instituted in themonth of November, 1845, it would have resulted in the discovery of theplanet. But, while fully conceding this point, we are by no means pre-pared to admit that existing circumstances would have warranted the im-mediate appropriation of the resources of any official Observatory to suchan object. It must be borne in mind that Mr. Adams’ results were thefruits of the first solution of the problem of planetary perturbation whichthe geometer, aided by analysis, had yet arrived at. It was reasonablethen to suppose that the position of the planet was not assigned with ahigh degree of accuracy, and that, in order to secure its discovery, a con-siderable region of the heavens would require to be submitted to a carefulexamination. In carrying this operation, however, into effect, no aid couldbe derived from any previous labours in Uranography, since a star maphad not yet been constructed for the part of the zodiac in which the planetwas then moving. The search, therefore, could only be accomplished bythe prosecution of an extensive course of observations, similar to thatwhich Mr. Cliallis undertook in the following year. Under such circum-stances it was imperative on the part of the astronomer, charged withofficial duties, to exercise due discretion in selecting the most favourableperiod for devoting the resources at his disposal to a systematic search forthe planet. This line of conduct was more especially prescribed in thepresent case, as two months had already elapsed since the planet was inopposition, and the chance of effecting its discovery before it was lost inthe rays of the sun had in consequence considerably diminished. The sub-sequent history of the circumstances connected with the discover}' of theplanet confirm this view of the subject. Although M. Le Verrier an-nounced the existence of the undiscovered body as early as the 1st June,1840, and confidently asserted, as the result of a careful analysis, that theerror in the position he assigned to it did not exceed 10°, it does not ap-pear that a single telescope was directed to the heavens in search of thedisturbing body at any Observatory on the Continent of Europe previousto the night of its actual discovery towards the close of the month of Sep-tember of the same year. Even at the Royal Observatory of Paris, whichis under the direction of the illustrious philosopher who originally sug-gested to M. Le Verrier the subject of the perturbations of Uranus , andwhere it might have been expected that the remarkable results obtained bythe geometer would have excited peculiar interest, no steps appear to havebeen taken towards the actual discovery of the planet, although a monthhad elapsed between M. Le Vender's announcement of his final results onthe 31st August, 1846, and the receipt of the intelligence from Berlin,containing the accounts of Galle’s discovery. That a search for the dis-turbing body would eventually have been undertaken at more than oneObservatory is quite certain; but it was not the opinion of any astronomer,that without the aid of a star map, this object could be successfully accom-plished, except by an extensive and systematic course of observation.“ Had it not been for the infinitely favourable circumstance,” says M. Encke,“ of possessing a map whereon one might be sure to find the positions of allthe fixed stars down to the tenth magnitude, I do not think that we shouldhave found the planet.” * These remarks will appear superfluous to those

Comptes Rcndus, tome xxiii. p. 6C2.