Various wind gauges and other meteorological recording instruments are attached to the roof of the tower.
They cannot carry out weather observations because they have no rain or wind gauges or thermometers.
The third method of determining the wind is used in conjunction with the wind gauge bar.
Any number of wind measurements or navigation calculations could be carried out on the compass face using the wind gauge bar.
If the wind is strong enough, then the snow may be blown across the wind gauge and the amount of snow fallen will be under-reported.
It is the same type of back-sight, but the wind gauge has been put on and it is a delicate thing.
