98 ANNUAL OF SCIENTIFIC DISCOVERY. 



inch lens, would be 52,320times ; and that again by the six-inch, dis- 

 tant from the eye twelve feet, or twenty-four times its focal distance, is 

 reduced twenty-three times; making the total reduction 1,203,360 

 times. 



It becomes now an important matter to ascertain, as nearly as possi- 

 ble, the proportion of Alight lost by and through the media above de- 

 scribed the looking-glass, the prism, and two lenses though joining 

 the little lens with balsam to the prism, it may be regarded as one 

 piece. I have only investigated by experiments with artificial lights ; 

 but I find, when the mirror is placed at the angle which the sun re- 

 quires at the date above given, the difference in the distance at which 

 a direct light, and the same light reflected, are brought to a minimum 

 visible, does not exceed one-eighth part of the entire distance, and 

 could not reach one-seventh, when the prism and lenses were in- 

 terposed. 



Again : the image of the highly-illuminated atmosphere, for some 

 degrees about the sun, is admitted with the sun's direct light, through 

 the little lens, to the dark chamber ; and the light, thus augmented, is 

 observed in contrast with a darkness greater than that of a clear noc- 

 turnal sky. The entire loss by reflecting and absorbing is manifestly so 

 small, and the light of the sky in the immediate vicinity of the sun, so 

 great, that I can readily believe the waste, in effect, is fully made up ; 

 especially when considering the absolute blackness of the ground upon 

 which the light in the dark chamber is projected ; and I can find no 

 reason to doubt that the sun would appear as a star of the sixth magni- 

 tude, or be only just visible to the unassisted human eye, even setting 

 aside the idea of an extinguishing medium, if removed 1,200,000 times 

 his present distance; and at 100,000 times his present distance, he 

 would only rank as a pretty bright star, of the first magnitude ; though 

 his parallax would be double that imputed to any star in the whole 

 heavens. If his intrinsic splendor generally proves to be less than that 

 of those stars whose distances have been measured, we need not infer 

 that it is less than the average of existing stars ; for, in case of a diver- 

 sity among them, bearing any proportion to that among organic bodies, 

 on the face of the earth, or the planets of our system where the num- 

 bers are so comparatively small, the visible stars would, of course, ex- 

 ceed, upon the average, our sun ; for, by the laws of perspective, the 

 small ones would be lost to our view, at distances from which the 

 brighter individuals would appear as conspicuous objects. Such would 

 be the case with telescopic magnitudes, as well as with those visible to 

 the naked eye. The number of stars visible, by aid of the more pow- 

 erful telescopes, is far less, in proportion to the power of the instru- 

 ments, than those visible to the unassisted eye, or with smaller tele- 

 scopes. This fact has given rise to the doctrine of an extinguishing 

 medium in space ; which is accepted by the most able astronomers as 

 the truth, and has been the foundation of much ingenious reasoning. 



Plausible or probable, as this appears, I see no difficulty in under- 

 standing that an exceedingly great diversity in the intrinsic brightness 

 of the stellar orbs, promiscuously scattered through space, might result 

 in the same appearances as those on which this doctrine is founded. 

 For, at the smaller distances, we should see the whole, both great and 

 small, when using only moderate powers ; but in the regions bounding 



