XLII 



INTRODUCTION. 



THE LINES ON THE CHARTS, &c. 

 Represents the sun in its position at the time of observation. 

 Star of the first magnitude, 8 rays. 

 Star of the second magnitude, 7 rays. 

 Star of the third magnitude, 6 rays. 

 Star of the fourth magnitude, 5 rays. 

 Star of the fifth magnitude, 4 rays. 



The central, straight line, up and down the page, is the ecliptic (consult chart No. 1), the 

 guiding line in these charts.- The scales of degrees, at the bottom and sides of the plate, are 

 those of latitudes and longitudes. 



The upward line, curving about the ecliptic, is the equator. (See also chart No. 1.) 



The lines across the plates, mostly towards the bottom 

 of the plate, either full, or composed of full lines and 

 dashes/ represent the spectator's horizon at the times 

 specified. 



The line with dots, towards the top of the plate, shows the course of the spec- 

 tator's zenith during the observations, his zenith point at each observation being 

 noted. The object is to show his relative positions toward the ecliptic or plane of 

 the nebulous ring, during this period. Where there is but one observation, his 

 zenith is denoted by a dot with a circle around it ; the time also being specified. 



The full lines which pass upward on (he chart, curve 

 ver and return again, are the boundaries of the 

 h-onijer Zodiacal Light, at the times noted with each. 

 i In some instances, the apex is omitted. 



