552 THE POPULAR SCIENCE MONTHLY. 



determined to erect a great astronomical institution. He found 

 most of the labor of fitting up the observatory yet to be done. 

 He was given, as temporary quarters, with poor provisions for 

 his work, a bastion on the Rhine called the Old Zoll. 



With irrepressible industry he composed his beautiful work, 

 the New Uranometry, or charts of the stars visible to the naked 

 eye in central Europe, with their true magnitudes taken immedi- 

 ately from the sky. Taking up the field, hitherto but little 

 worked, of the variable stars, he adopted the methods of Herschel, 

 improving the notation. He expressed all the differences in light 

 by numbers, and thereby opened the possibility of investigating 

 phenomena which no one before him had subjected to calculation. 

 Beginning in December, 1838, with observations of Mira Ceti, he 

 included Algol in February, 1840, /? Lyra3 and other stars in the 

 summer of the same year, and, with these, telescopic stars. At the 

 same time he tried to excite interest in the subject in other quar- 

 ters, at first with limited, afterward with increasing success ; and 

 in a short time this branch of our knowledge of the fixed stars 

 assumed a new form. The discovery in 1843 of the decrease in 

 Algol's period led to more thorough researches on the changes of 

 the periods and their laws. Closer examinations of the older ob- 

 servations were brought in, and much that had been almost lost 

 was looked up and collected. The observations were continued 

 for many years, and it was not till 1859 that Argelander, without 

 giving up his interest in the work, ceased to prosecute it actively, 

 when his eyes were becoming weak, and when the general par- 

 ticipation of others in it had satisfied him that it would be car- 

 ried on. 



The New Uranometry had originated, not only in the desire to 

 present an enumeration of the stars, to clear the charts of errors 

 of position and designation, and to furnish observers with the 

 naked eye Avith a good atlas for orientation, but also out of the 

 conviction of the importance of leaving to posterity a good repre- 

 sentation of the relative magnitudes of the brighter fixed stars, in 

 order to make the real secular variations in brightness distin- 

 guishable from fancied ones. The dissertation, De fide Uranome- 

 tricB Bayeri, is a contribution in this direction, and has the great 

 merit of setting out in the right light the true principles from 

 which Bayer had allowed himself to be led in the construction 

 of his charts. Argelander's methods of observation in this field 

 are summarized in an essay in Schumacher's Jahrbuch for 1844, 

 from which many who have interested themselves in this line 

 have drawn their instructions. The same work contains the first 

 general summary of our knowledge of the subject from Arge- 

 lander's hand, an important revision of which is found in Hum- 

 boldt's Cosmos. This treatise also bespeaks many other phe- 



