566 JOHANN FRIEDRICH JULIUS SCHMIDT. 



prehensiveness it far exceeds any other attempt of its kind. Thus, 

 while Lohrmanu's map includes about 7,200 craters, and Miidler's 

 7,800, Schmidt's chart includes the extraordinary number of nearly 

 33,000. 



Next or perhaps equal in importance is Schmidt's series of ob- 

 servations on the variable stars, which extend from 1842 to 1883, and 

 which probably outnumber those of all other observers of his time 

 combined. It has been his practice to publish annually, in the As- 

 tronomische Nachrichten, the provisional results, and it seems pecu- 

 liarly fitting that the same number of that journal which contains the 

 announcement of his death contains also the last of this memorable 

 series. Schmidt made several notable discoveries of new variables. 

 The original records of his observations have been deposited in the 

 Astro-Pliysical Observatory at Potsdam, and will form an almost 

 mexhaustible treasure to future workers in this field. 



In still another department, that of the solar phenomena, Schmidt 

 was a remarkably fruitful and persevering observer. In 1857 he pub- 

 lished the results of a continuous eleven-year series of observations 

 on the vm-spots, which are simultaneous with, and serve to complete 

 and supplement, those of Schwabe. He gives tables of the daily 

 number of spots and groups, with remarks on special phenomena, 

 and adds a discussion of them. His speculations on the possible 

 connection of the sun-spot period with the varying position of the 

 centre of gravity of the solar system with reference to the centre 

 of the sun itself, have not met with general acceptance. During the 

 last twenty years, also, this kind of observation has been perse- 

 veringly kept up by Schmidt, with the help in recent years of his 

 assistant, Alexander Wurlisch. 



The other labors of Schmidt, although important and in extent 

 sufficient to absorb the whole time and energy of an ordinary maTi, 

 can only be mentioned briefly here. lie was a persistent ol)server 

 from 1843 to 1879 of the phenomena pertaining to the Zodiacal 

 Light; made very large contributions to the fund of observations of 

 shooting-stars during the same period ; published a thirteen years' 

 series of observations on the Northern Lijrht ; determined micromet- 

 rically the positions of about three hundred nebul?e ; made very 

 elaborate drawings of the Great Nebula in Orion, and a chart of tlie 

 surrounding region ; has deposited at Vienna a beautiful drawing of 

 the Milky Way ; accumulated during forty years voluminous observa- 

 tions on the brightness of the principal planets, besides nearly six 

 hundred drawings of the surface of Mars and Jupiter ; made impor- 



