GOODK.] 
TRANSIT AND STADIA WORK. 
II 
rods being divided so as to read to hundredths. In point of !. 
probably neither of these conditions existed, even when the instrument 
was fresh from the hands of the maker and when the rods were newlj 
graduated at Spokane, and much less likely is it that they existed 
when the instrument was subject to rough field usage and the rods 
were used under entirely different and variable circumstances. Ii 
was believed, however, that they could be relied upon in determining 
intermediate distances between points the exact distances between 
which were known, and so long as the ratio hot wen the wire interval 
and the graduated portions of the rods remained 
nearly constant the purpose intended to be sub- 
served would be accomplished. Tims, when a lino 
was run with the stadia between two points whose 
positions were rigidly fixed by triangulat ion and t he 
resulting error was proportionately distributed, su Hi- 
ciently accurate results were obtained, much more 
nearly accurate than could have been obtained l>y 
chaining, especially after certain corrections had 
been applied. 
The method used in running the random line was 
as follows: 
The line started from an astronomic azimuth, the 
initial point being on a high ridge and marked with 
a large signal. This signal was, when possible, used 
as a backsight, the instrument being transited in t he 
direct and reversed position and the mean of the t wo 
points determined for the foresight being adopted. 
Of course in a timbered country it was generally 
not possible to see the backsights for any great 
distance, but whenever a ridge was crossed the 
trees were cut out (see Pis. IX and X) and a new 
backsight was established. In addition, frequent 
observations for astronomical azimuth were made, 
and thus additional checks were obtained. If any 
considerable discrepancj^ was discovered between 
the astronomical azimuth and the instrumental line, m U i 
the latter was rerun in order to obtain a satisfactory 
check. Further, the line was connected with the triangulation and 
accurately adjusted thereto in azimuth as well as in distance. When 
the line was adjusted to the triangulation it was apparent that the 
transit man had introduced into his work a decided personal equation, 
which had the effect of constantly swinging his Line in azimuth too far 
to the westward, as will appear hereafter. The stadia distances were 
read from both backsights and foresights, so that the Length of each 
sight was obtained in duplicate, one distance depending on rod No. l 
and the other on rod No. 2, the mean being adopted. In the name 
