90 I. P. Косн. 
which formed the vertices of an equiangular triangle, while the fourth 
hole was in the centre of this triangle. In the latter hole a small 
brass bolt was placed; in the three others were cast the legs of a 
solid iron table (Fig. 3) the top of which was about 2.5 cm thick. In 
the centre of the top of the table there was a hole for the central 
screw of the instrument. When the instrument was clamped on to the 
iron table, it was thus solidly connected with the granite pillar. When 
adjusting it by means of letting 
the plumb down over the brass 
bolt in the surface of the pillar 
(see Fig. 3), one could with great 
accuracy replace the instrument 
in its original position, when- 
ever it had been removed from 
the pillar, which circumstance, 
however, came to be of no im- 
portance in our case, as we did 
not succeed in getting a meridian 
mark of which we could make 
any practical use.!) 
By levelling with a Stampher 
levelling instrument the height 
over mean sea level was deter- 
mined as: 
Brass bolt in the granite 
Pullers.) Kran ae 13.46 m 
Top of the iron table . 13.67 - 
Teleseopen er 20 13.89 - 
Upper part of the wall 
of the Observatory. . 13.84 - 
Fig. 3. Granite pillar with iron table and DUR! 
instrument. From this it will appear that 
from the Observatory we could 
measure zenith distances of a little more than 90°. 
The construction of the granite pillar turned out to be practical, 
and this was also the case with the manner in which the fundamen- 
tal plinth was arranged. 
We had originally intended to establish a meridian mark, chiefly 
to be used in the observations of time. However, we had made no 
1) An error in the adjustment through the plumb of 5mm must, in case the di- 
stance of the meridian mark was one kilometre, occasion an error in azimuth of 
= 
2 
ee about 1”. 
