178 Solar Eclipse of July Sth, 1842. 



tinctly to see some of these appearances through the red eye-piece 

 of the former, though none was visible through the green screen 

 of the latter instrument. At Washington, where the eclipse was 

 nearly central, no distortion of the hmb of the moon could be 

 seen through the double screen above mentioned, and the cusps 

 of the sun just before and after the ring, were as pointed as nee- 

 dles. The Committee of the Philosophical Society of Philadel- 

 phia, in their report on this eclipse, say, " This suggestion is one 

 of great importance, as it seems to furnish evidence of the exist- 

 ence of a lunar atmosphere, through which, as through our own, 

 the red rays have the greatest penetrative power. It also leads 

 to new views concerning the cause of the remarkable appearances 

 of the beads of light and the dark lines frequently noticed ; since 

 it shows that their appearance may be completely modified by a 

 change in the color, and consequently in the absorbing power of 

 the screen glass through which they are observed." It is be- 

 lieved that on another account will this suggestion if well founded 

 be of great importance, viz. in its obvious tendency to diminish 

 if not wholly remove, the discordancies not unfrequently found 

 in the best observations on solar eclipses and transits of Venus, 

 and which with regard to the latter in 1761 and 1769, were so 

 great as materially to diminish the value of this method of deter- 

 mining the distance between the earth and the sun. 



The elements of the eclipse were computed from the lunar tables, 

 both of Burckhardt and Damoiseau, and as they appeared to differ 

 in their results by about 13''' of longitude, the mean or average 

 of the results was adopted, which it is hoped will be found more 

 conformable to observation. As these tables are adapted to the 

 meridian of Paris, the time of that meridian has been retained, 

 but the longitudes of the places are counted from Greenwich, 

 which is 2° 20' 23" west of the former. The eUipticity was 

 considered g^oth. Bui no correction was applied for irradiation 

 and inflection, which if allowed would cause the eclipse at each 

 place to begin about ten seconds later, and to end about eleven 

 seconds earlier than the time herein after stated. The latitudes 

 and longitudes of the several places, were with a few exceptions, 

 taken from the English and French Nautical Almanacs. 



