spherical triangle P F K, the longitude of F corresponding to its latitude as given 
by the foregoing formula, and if the difference between the two determinations 
amounted to 2" (as it sometimes did, when the azimuth of the line of observation 
thus reducing the size of the trapezoid C N D M, and the consequent error. Also, 
from this same triangle the arc F K was computed. 
The heights of the meteor (column 14th), for the different positions of F, were 
readily obtained by proportional parts from the 5th column of Table 1st, and the 
mean time at Washington was obtained, in the same way, from the 9th column of 
that table, which, corrected for the difference of longitude, gave the local time 
(column 15 th). 
The altitude and parallax of the meteor, at the several points (columns 8th and 
11th) were computed thus: Let G in the following dia 
gram represent the centre of the earth, M the meteor, K 
the place of observation, H K the sensible horizon, K F G 
the vertical circle in whose plane the altitude M K H was 
measured, and K F an arc of the same, as in the preced 
ing diagram. Then in. the plane triangle K M ( 7 , the sides 
K G and M G being known, and also the angle at G , 
since it is measured by the arc K F , already found, the 
angles at M and K were readily found, the former of which 
is the parallax, and the latter, diminished by the right 
angle H K C gave the altitude.