322 Prof. E. Loomis on the Aurora of 1859. 
If we combine the last seven observations of the preceding 
Table, we shall find that the lower limit of the auroral light was 
elevated fifty miles above the earth’s surface, and that its south- 
argin was vertical over the parallel of 25° 15’ north lati- 
tude in Florida. Now the dip of the magnetic needle in Florida 
in latitude 25° 15’ is 55° 40’; and if we draw GH, figure 2, 
making an angle of 55° 40! with the curve line EF, which rep- 
resents a portion of the earth’s surface, and assume that the line 
GH represents the southern boundary of the auroral illumina- 
tion, and that the first five observations of Table III. were made 
upon the point H, we shall find that the wpper limit of the auro- 
ral light was elevated 495 miles above the earth’s surface, and 
that its southern margin was vertical over the parallel of 22° 
30’ N. latitude in Cuba, 
This illumination consisted chiefly of luminous beams or COb 
Tisealicni of a magnetic nee 
when freely suspended; that is, in the United States, these 
