HimaAwava Mounrains. 24} 
that nothing of this kind had taken place, and this attention, so necessary, 
io give any certainty to the operation, I never omitted. 
20. Tue rods being now placed on the stands, which had been. pre- 
viously adjusted, being near the truth, a few minutes. sufficed to set them 
_ perfectly correct. or this purpose the same telescope was used, and a 
small piece of wood placed on the rod;: the top of which had the same 
height above it as the axis of the telescope. - This was made to correspond 
with the cross on the picket, by means of small wedges puslied underneath, 
or on one side of the rod. Such ar adjustment was only required for the 
fore end of the advanced rod, -and for the junetion of the two;. the athe 
parts were easily brought right, by means of the brass wire stretched 
on them. 
91. Tue rods lying now truly on the_line- of the base, and in the 
hypothenusal plane, the languette was pushed out to meet the fore end of the 
fixed pair, and the reading entered in the book. The interlocking Nonius 
of the pair was next read and entered, and then the Comparator with the 
thermometer. When it became necessary to change the direction of the 
hypothenuse, and before the last pair of rods of the old hypothenuse had 
been removed, the inclination was observed with the theodolite, which had 
been originally set to the proper height as before noticed. The angle of 
elevation was observed on both faces, and the theodolite always careiully 
levelled, and as the instrument is capable of measuring vertical angles to a 
minute, there can be no great chance of error, involved in the reduction, 
depending on this element. 
