wooden astronomical tablets with Mr Gresswell and others:  they were fully examined by Mr Ellis.—­In this year I was much engaged on schemes for compasses, and in June I sent my Paper on Discussions of Ships’ Magnetism to the Royal Society.—­On Dec. 6th the mast of the Observatory time-ball broke, and the Ball fell in the Front Court.—­On Aug. 4th my valued friend Mr Sheepshanks died; and on Aug. 14th I went to London to see the Standard Bars as left by him.  Afterwards, on Oct. 25th I went to Reading to collect the papers about Standards left by Mr Sheepshanks.—­I made a mechanical construction for Euclid I. 47, with which I was well satisfied.—­On Apr. 13th I joined a deputation to the Chancellor of the Exchequer (Sir G. Cornewall Lewis) on Decimal Coinage.”

Of private history:  “I was at Playford for a large part of January.—­On Mar, 26th I went to Reading, to visit Mr Sheepshanks, and afterwards to Silchester and Hereford.—­On June 21st I went with my wife and two eldest sons to Edinburgh and other places in Scotland, but residing principally at Oban, where I hired a house.  Amongst other expeditions, I and my son Wilfrid went with the ‘Pharos’ (Northern Lights Steamer) to the Skerry Vohr Lighthouse, &c.  I also visited Newcastle, &c., and returned to Greenwich on Aug. 2nd.—­From Oct. 12th to 17th I was at Cambridge.—­On Dec. 24th I went to Playford.”

CHAPTER VII.

AT GREENWICH OBSERVATORY—­1856 TO 1866.

1856

“In the Report to the Visitors there is an interesting account of the difficulties experienced with the Reflex Zenith Tube in consequence of the tremors of the quicksilver transmitted through the ground.  Attempts were made to reduce the tremor by supporting the quicksilver trough on a stage founded at a depth of 10 feet below the surface, but it was not in the smallest degree diminished, and the Report states that ’The experience of this investigation justifies me in believing that no practicable depth of trench prevents the propagation of tremor when the soil is like that of Greenwich Hill, a gravel, in all places very hard, and in some, cemented to the consistency of rock.’—­With respect to the regulation of the Post Office clocks, ’One of the galvanic clocks in the Post Office Department, Lombard Street, is already placed in connection with the Royal Observatory, and is regulated at noon every day ... other clocks at the General Post Office are nearly prepared for the same regulation, and I expect that the complete system will soon be in action.’—­Under the head of General Remarks a careful summary is given of the work of the Observatory, and the paragraph concludes as follows:  ’Lastly there are employments which connect the scientific Observatory with the practical world; the distribution of accurate time, the improvement of marine time-keepers, the observations and communications which tend to the advantage of Geography and Navigation, and the study, in a practical