414 ‘ &. Newcomb on observing the Corona, 
behind the larger screen and see whether he can make it hid 
the entire luminosity surrounding the sun, and, if not, w 
note very carefully the position of any object or luminosity 
not hidden. He will then make similar observations with the 
other screens in succession until one is found which shows the 
corona on all sides at once. 
_ The law of diminution of light from the inside to the out- 
side of the annulus can, perhaps, be most accurately deter- 
phere Surrounding the sun in a state of equilibrium. Though 
such an atmosphere were of hydrogen, and at a temperature of 
100,000° Fahr nheit, its density would be reduced one-half in 
ve | . . . 
miles, it would rare as to be altogether invisible, unless 
sup temperature to be many times 100,000 
eclipses of the sun, and that its ter brilliancy on the side 
— the moon least atid! would be very strongly 
