H. C. Lewis—Zodracal Light. 443 
band, along? always much fainter than any central portions 
of the Via Lactea. It often appears to form an oval whose 
major axis is parallel to the ecliptic. At such times its major 
axis may be 15° in length. This effect is probably caused by 
the brightness of the zodiacal band on either side of it, for care- 
ful observations show that the brighter portion is approximately 
circu 
in the arene of. the gegenschein. Th nucleus is a small 
nue 
erally the gegenschein appears as a nebulous pass of equally 
diffused light. 
Perhaps the most interesting fact concerning the gegenschein 
which is clearly deduced from ee maps of its position, is that 
it always lies some 2°+ north of the ecliptic. ile a num- 
ber of observations place its center 8°—4° north of the ecliptic, 
not a single one makes it south of that line. This fact will be 
of importance in a theory of the gegenschein. 
he extreme faintness of both the gegenschein and the 
zodiacal band made it impossible to obtain any spectrum 
other than that given by diffuse star-light. 
Explanation ot Plate.-—Plate VI represents those apd det ch of vain Beeen- 
schein which were taken while it was ape the vernal equinox. These observa- 
tions, made at ‘different times and upon different maps, are (ors for the firat time 
plotted on one map and the line of the etigtin added. The bounding lines of the 
different gegenscheins represent boundaries of more or less diffuse portions; an 
the various circular figures on the plate are oe to be regarded as showing differ- 
ya : ty: 
e are merely indices to locali 
The dates of observations were as follows 
1. Feb. 4, 1880. 8. Mar. 5, 1872. 19. Apr. 5, 1880. 
2. Feb, 4, 1878, 9. Mar. 9, 1877. 14. Apr. 6, 1877. 
3. Feb. 7, 1880. 10. Mar. 15, 1877. 15. Apr. 6, 1878. 
4. Feb. 9, 1877. 11. Mar. 25, 1879. 16. Apr. 7, 1880. 
5. Feb. 14, 1879. 12. Mar. 31, 1880. 17. Apr. 10, 1877. 
6. Feb, 21, 1879. 13. Apr. 5, 1877. 18. Apr. 14, 1877, 
7. Mar. 5, 1880. 
just before moonrise. It may have been owing to an snferigr 
horizon, but, although careful search was made, at no time 
has the ‘present writer been able to detect any such 2 ain gee 
The light which precedes the rising of the moon is uni- 
formly to rise at right angles to the horizon. This light 
* U.S, Japan Exped., iii, 329, et seq. - 
