174 Captain Owen on Circummeridian Altitudes. 
Z; o being o X sin. A‘ and t' =t X sin. L’; since, then, the ZP Zo, 
P©Z may be found by any two of the three differences, and A‘ 
and D*are given, so L’, the colatitude, may be found. (To reduce 
i to“, a near latitude may be used without error.) 
Explanation of Figure No. 3. 
Let OTA#R represent a part of the apparent track of a celes- 
tial object near the meridian. 
Let ZT PN represent a part of the meridian, in which Z the 
zenith, N the nadir, T the point of the object’s meridian passage, or 
ztQn may represent the meridian in which ¢ is the point of the 
object’s meridian transit. 
Let Txt be a parallel of altitude equal to the altitude when the 
object is in the meridian, and 
Let OPyQR be another parallel of altitude, taken at any given 
time from (T or A) the meridian, or from the apex A (the point 
where the celestial object attained its greatest altitude, or nearest 
approach to the zenith). 
Let A be the apex or summit of the celestial object’s apparent 
track, or point of its nearest approach to the zenith. 
