HISTORY OF PHYSICAL ASTRONOMY.

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Almanac for 1850. If anything was wanted to complete the vindicationof Mr. Adams’ claims, it v>m> amply supplied by this Memoir. Apart fromall consideration of the brilliancy oi Uio result in relation to theplanetary system, it exhibits an admirable specimen oi 01 .^ of

analysis to one of the most difficult subjects of physical astronomy, beingplanned with a sagacious appreciation of the difficulties peculiar to suchabstruse researches, and pursued throughout its details with exquisitemathematical skill.

The impression produced by tlio communication of Mr. Airy to theAstronomical Society was such as always naturally ensues when truth ispresented in the form of a plain statement of facts, stripped of all ingenuityof reasoning or flourish of rhetoric, and relying for acceptance solely onthe authenticity and innate strength of the evidence by which it is sup-ported. The most illustrious philosophers, of Europe , while justly acknow-ledging the originality and brilliancy of M. Le Vender’s researches on theperturbations of Uranus , have cordially concurred in awarding a similartribute to Mr. Adams, and tlie names of both these geometers are nowimperishably associated with the theoretical discovery of the planet bywhich these perturbations were produced.

It has been asserted that as M. Le Vender’s researches alone wereinstrumental in leading to the actual discovery of the planet by Galle,Mr. Adams, whose labours exercised no influence on the observations ofthe German astronomer, cannot justly be placed in so high a position ashis illustrious contemporary. This opinion we imagine to have originatedin an imperfect discrimination of the respective functions of the geometerand tlie observer. The geometer, relying upon tlie firmly-establishedprinciples of the theory of gravitation, recognises in the irregularities ofone of the planets unequivocal evidence of the existence of an unseenmember of the solar system, and, by a successful application of analysis,he arrives at a knowledge of its position. The observer, guided by theinstructions of the geometer, searches the heavens, and succeeds in dis-covering optically what the geometer had previously discovered theoretically.Each has his peculiar duties, totally distinct from those of the other; andwe should be acting in opposition to the plainest maxims of justice byascribing to the one any credit on account of duties performed by thoother. The eclat which so justly surrounds the optical discovery of theTrans-Uranian planet must be shared severally by the Berlin Academy ofSciences under whose auspices the charts of the zodiac have been con-structed, by Dr. Bremiker who so skilfully designated the region of theheavens in which the planet was moving, and by Dr. Galle, who sopromptly availed himself of the publication of Dr. Bremiker ’s chart. Ifwe would look for the real grounds of M. Le Vender's renown, we mustabandon the glorious spectacle of the heavens and enter the solitarychamber of the geometer. It is there that he justly becomes the object ofour admiration, as he advances step by step along the intricate maze ofhis researches, vanquishing each successive difficulty by the ready re-sources of his genius, and cheerfully executing calculations which arealmost appalling to contemplate; until a bright flood of light is finallydiffused over his labours, and the distant member of our system, whichhuman eye has not yet seen, discloses itself to his purely intellectual scru-tinies with all the certainty of demonstrative reasoning. If this be thejust view of M. Le Vender's labours in relation to the discovery of theTrans-Uranian planet, we are then constrained by parity of reasoning to