200 MEMOIR OF ENCKE. 



steadfastness of the instruments was thereby still more prejuiliced, and the con- 

 cussion of the intercourse in the streets hindered all exact measurement. To 

 this must be added the continued noise and the impurity of the atmosphere. 

 Eucke wrote, soon after his arrival, to Bessel, that the only serviceable instru- 

 ment was the Frauenhofer heliometer, though this, too, could scarcely be used 

 on account of the insecure stability. The best thing about the observatory was 

 the library, limited as it was. 



After Bode's death the erection of a new observatory was canvassed, and if 

 at first Encke expressed himself with some humor about the proposed destina- 

 tion thereof, he nevertheless soon entered earnestly into the scheme. Bessel 

 urged him to consider well " whether the satisfaction in the possession of an 

 observatory or the hindrance to those labors to which he owed his renown, were 

 greatest." In a following letter it is said: ^' I regard you as the astronomer on 

 whom the superintendence of the calculations is obligatory. Others have other 

 functions : you, my dear Encke, can undertake nothing new without neglecting 

 what has earlier claims upon j^ou, and is in reality of more essential importance. 

 Be cautious, I pray you, in this matter." 



Encke now addressed himself to Humboldt with the request that he would 

 decide upon the proper objects of an observatory for this country. Ordinary 

 observations, such as can here be scarcely conducted, are at present, he argued, 

 without value. If it were proposed to afford opportunity for serviceable astro- 

 nomical observations, a new observatory' Avould be indispensable. This commu- 

 nication led Humboldt to second the movement for building a new observatory, 

 which was authorized October 15, 1828, at the same time with the ordering of 

 several important instruments from artists of the besf repute. The purchase of 

 a large refractor, which Frauenhofer had nearly finished, immediately follo\ved. 



Encke's questions drew from Bessel a prompt answer respecting the judicious 

 arrangement and equipment of the observatorj'^, but still accompanied with pre- 

 cautionary counsels : "I think that neither your efficiency nor satisfaction will 

 gain anything if you convert yourself into an observatory astronomer. In my 

 opinion the observatory^ should not be the main point with you. An assistant, 

 adjunct, or whatever you may please to call him, should do the work therein. 

 Immeasurably more is to be done in order to save the material collected from 

 being lost and suitably to use it. If this is once accomplished, it will be then 

 for you to show to what ends further observations may be directed with the most 

 fruitful results." 



In the beginning of 1835 the building was finished, the instruments soon after 

 put in position, and the activity of the new observatory commenced with the 

 observation of Halley's comet. The observations which, since that epoch, have 

 been instituted, partly by Encke himself and pavtly b}' his assistants, have been 

 publislied in four volumes, which will soon be followed by a fifth. 



How close were the friendly relations between Bessel and Encke is Seen from 

 the foregoing comnnmications. They were knit still more closely when Encke 

 took charge of the corrections of the press for the Fundamcnta Astronomia;. 

 After Bessel, on a journey in 1819, had formed a jiersonal acquaintance with 

 Encke, he wrote to him : " I see in you not only a firm stay of astronomy in Ger- 

 many, but a cherished and outspoken friend ; botli considerations prompt me to 

 wish that you should continual to accord to me a portion of your aff'ectionate regard." 



On his return to Konigsberg Bessel spoke with enthusiasm of the gifted and 

 estimable astronomer whose first labors had deservedly raised him to the highest 

 consideration. The correspondence which followed was not restricted, lilvc that 

 between Olbers and Bessel, to scientific connnunications and the more serious 

 affairs of life, but was rather a confidential intercoranmnioii, which embraced at 

 once their respective enterprises, whether begun or contemplated, and the frankest 

 utterances on subjects of ever}' nature. It is not to be disguised, however, that 

 Bessel gave freer scope to his feelings, while Encke often observed a certain 

 iiegree of reserve. This intercourse had already lasted some years, when we 



