--For the service of the
Clock Movement of the Great Equatoreal, a water-cistern has been
established in the highest part of the Ball-Turret, the necessity for
which arose from the following circumstance: The Water Clock was
supplied by a small pipe, about 80 feet in length, connected with the
3-inch Observatory main (which passes through the Park), at a distance
of about 250 feet from any other branch pipe. In spite of this
distance I have seen that, on stopping the water-tap in the
Battery-Basement under the North-East Turret, the pressure in the
gauge of the Water Clock has been instantly increased by more than 40
lbs. per square inch. The consequent derangement of the Water Clock in
its now incessant daily use became intolerable. Since the independent
supply was provided, its performance has been most satisfactory.--With
the Spectroscope the solar prominences have been mapped on 28 days
only; but the weather of the past winter was exceptionally
unfavourable for this class of observation. After mapping the
prominences, as seen on the C line, the other lines, especially F and
b, have been regularly examined, whenever practicable. Great care has
been taken in determining the position, angle, and heights of the
prominences in all cases.
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