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vatory at Brussels, who says, " Nous sommes a peine au milieu de 

 1832, et deja nous possedons les observations de M. Airy, pour toute 

 l'annee 1831 : et ce qui peut paraitre plus etonnant encore, toutes 

 ces observations sont calculees et discutees avec soin." 



It is interesting to observe the care with which he chose the objects 

 to which he should turn his attention as an astronomer, and the 

 constancy with which he stuck to his choice when once made. The 

 chief object, he says, must be such that it could be accomplished by 

 a single unassisted observer, and yet be so important as to be of 

 public use. After consideration he decided that the observations of 

 planets had at that time been so neglected, that one who wished to 

 revise the planetary tables would find himself destitute of the neces- 

 sary data on which to found his investigation. As soon, therefore, 

 as the Cambridge Observatory was placed under his direction, he 

 made the observation of planets the leading object of his labours. He 

 says in one of his reports that " hardly a single observation of a planet 

 has been lost when the transit was at sach an hour that in the 

 regular routine of observations it was practicable to observe it." The 

 wisdom of his choice is shown by the fact that his successor followed 

 closely the same objects. Other pressing wants in astronomy were 

 also present in his mind, and others again rose unexpectedly in the 

 course of his work. In reading his yearly volumes of observations, 

 one notices among other things the care which is taken to secure 

 accuracy. No labour is spared, no calculation is allowed to pass 

 without repeated examination. " To observe all night and to calcu- 

 late all day " is the description of an astronomer's duties given by an 

 astronomer. In the arrangement of his results, we notice, also, how 

 everything is subordinated to increasing their immediate utility as 

 well as securing accuracy in their details. 



When Professor Airy first went to the Observatory the only large 

 instrument was a transit, though this was one of the best of its 

 kind. So energetic an astronomer was not likely to be satisfied with 

 this ; accordingly in 1834 he obtained a large mural circle. In the 

 report for that year he describes the unexpected and annoying diffi- 

 culties which arose in connexion with that instrument. In the next 

 report we find that these difficulties have been overcome by considering 

 that the effects of the discordance of zenith points on direct and 

 reflexion observations are equal. Later on the great Northumberland 

 equatoreal was added. The establishment to work these was also 

 necessarily increased, and two assistants were given to him. 



Perhaps one of the most remarkable examples of Mr. Airy's insight 

 into astronomical questions is his discovery of a new inequality in the 

 motions of Venus and of the Earth. The attention of the Board of 

 Longitude having been directed to the state of the solar tables used 

 in the construction of the ' Nautical Almanac,' he was desired to 



