238 
LITTLEHALES. 
cumferences and a series of equally spaced radial lines have 
been drawn over the projection in lines of dashes. For the 
purpose of identification, the overlaid system of concentric 
circumferences is numbered serially from the center of the 
projection outward to the bounding meridian, and the radials 
are also marked by numbers indicating their angular dis¬ 
tance in minutes of arc counted in a clockwise direction 
from some fixed origin, like the line OS; so that, having 
plotted the declination and hour-angle of the observed celes¬ 
tial body at M, it is only necessary to note the number of 
the circumference and the number of the radial which pass 
through this position, and then, adding the co-latitude ex¬ 
pressed in minutes to the number of the radial, find the 
intersection, M', of the noted circumference with the radial 
whose number is the sum just found, and read off from the 
graduated arcs of the projection the altitude and azimuth 
of this point of intersection. 
In order that the required results may be found to the 
nearest minute of arc, the stereographic projection is being 
constructed with a diameter of twelve feet; but this in one 
continuous sheet will obviously be of unmanageable size for 
ordinary use, and will be changed to convenient form by 
being cut up into the overlapping sections which form the 
pages of a book. In this form the projection can be used 
with the same facility as if preserved in one continuous sheet; 
for it has been pointed out that in effecting the required solu¬ 
tion only those parts of the projection are involved which lie 
in the immediate vicinity of the points whose coordinates 
are to be plotted or read off. 
To complete the illustration of the method it will be suffi¬ 
cient to treat one example, inasmuch as the process of solu¬ 
tion is identical in every case. 
EXAMPLE. 
At sea, April 2, 1902, about 6 h 35 m p. m., in latitude 39° 
16' N. and longitude 60° 00' W. by estimation. Observed 
a Aurigse, bearing N. 60° W. per compass, to be in altitude 
