s ^Jfe^^W 



v, A*. ~ .\ '- ( ~ " 



x-',W .- ' \s >** * ; ^ 



ia^c^ifc.i^j 



^ , ?*fe. 



r-^W^/' 



FIG. 1 8. Hydrogen Flocculi surrounding Sun-spots, showing 

 right- and left-handed Vortices, September 9, 1908. 



mirrors, much thicker than those of the Snow 

 telescope, are but little affected by the sun's heat. 

 Elevated 60 feet in the air, they also escape some 

 of the warm currents rising from the hot soil. 

 The results are a decided improvement in the 

 sharpness of the image and a prolongation of the 

 period during which good observations are possible. 

 Another advantage, quite as important, follows 

 from the use of an underground chamber to con- 



