Yesterday we made some alterations in the mounting of the great mirror.  We found that sundry levers were loose which ought to be firm, and we conjectured with great probability the cause of this, for correction of which a change in other parts was necessary.  The mirror was then found to preserve its position much more fixedly than before....  At night, upon trying the telescope, we found it very faulty for stars near the zenith, where it had been free from fault before.  The screws which we had driven hard were then loosened, and immediately it was made very good.  Then we tried with some lower objects, and it was good, almost equally good, there.  For Saturn it was very greatly superior to what it had been before.  Still it is not satisfactory to us, and at this time a strong chain is in preparation, to support the mirror edgeways instead of the posts that there were at first or the iron hoop which we had on it yesterday.

Nobody would have conceived that an edgewise gripe of such a mass of metal could derange its form in this way.

Last night was the finest night we have had as regards clouds, though perhaps not the best for definition of objects.

THE CASTLE, PARSONSTOWN,
1848, Sept. 2.

I cannot learn that the fault in the mirror had been noticed before, but I fancy that the observations had been very much confined to the Zenith and its neighbourhood.

1849

“In July the new constant-service water-pipes to the Observatory were laid from Blackheath.  Before this time the supply of water to the Observatory had been made by a pipe leading up from the lower part of the Park, and was not constant.—­In May the new staircase from my dwelling-house to the Octagon Room was commenced.—­In the Report to the Visitors there is a curious account of Mr Breen’s (one of the Assistants) personal equation, which was found to be different in quantity for observations of the Moon and observations of the Stars.—­The most important set of observations (of planets) was a series of measures of Saturn in four directions, at the time when his ring had disappeared.  They appear completely to negative the idea that Saturn’s form differs sensibly from an ellipsoid.—­Among the General Remarks of the Report the following appears:  ’Another change (in prospect) will depend on the use of galvanism; and as a probable instance of the application of this agent, I may mention that, although no positive step has hitherto been taken, I fully expect in no long time to make the going of all the clocks in the Observatory depend on one original regulator.  The same means will probably be employed to increase the general utility of the Observatory, by the extensive dissemination throughout the kingdom of accurate time-signals, moved by an original clock at the Royal Observatory; and I have already entered into correspondence with the authorities of the South Eastern Railway (whose line of galvanic communication