less than 1/6.  The wires were promptly dismounted, and silk skeins substituted for them.  With these, the torsion-coefficient is about 1/210.’—­The Dip-Instrument, which had given great trouble by the irregularities of the dip-results, had been compared with two dip-instruments from Kew Observatory, which gave very good and accordant results.  ’It happened that Mr Simms, by whom our instruments now in use were prepared, and who had personally witnessed our former difficulties, was present during some of these experiments.  Our own instrument being placed in his hands (Nov. 10th to 19th) for another purpose, he spontaneously re-polished the apparently faultless agate-bearings.  To my great astonishment, the inconsistencies of every kind have nearly or entirely vanished.  On raising and lowering the needles, they return to the same readings, and the dips with the same needle appear generally consistent.’  Some practical details of the polishing process by which this result had been secured are then given.—­After numerous delays, the apparatus for the self-registration of Spontaneous Earth Currents was brought into a working state in the month of March.  A description of the arrangement adopted is given in the Report.—­’All Chronometers on trial are rated every day, by comparison with one of the clocks sympathetic with the Motor Clock.  Every Chronometer, whether on trial or returned from a chronometer-maker as repaired, is tried at least once in the heat of the Chronometer-Oven, the temperature being usually limited to 90 deg.  Fahrenheit; and, guided by the results of very long experience, we have established it as a rule, that every trial in heat be continued through three weeks.’—­’The only employment extraneous to the Observatory which has occupied any of my time within the last year is the giving three Lectures on the Magnetism of Iron Ships (at the request of the Lords of the Committee of Council on Education) in the Theatre of the South Kensington Museum.  The preparations, however, for these Lectures, to be given in a room ill-adapted to them, occupied a great deal of my own time, and of the time of an Assistant of the Observatory.’—­’Referring to a matter in which the interests of Astronomy are deeply concerned, I think it right to report to the Visitors my late representation to the Government, to the effect that, in reference to possible observation of the Transit of Venus in 1882, it will be necessary in no long time to examine the coasts of the Great Southern Continent.’”

Of private history:  “There were the usual visits to Playford at the beginning and end of the year.—­From June 18th to 26th I was on a trip in Wales with my sons Hubert and Osmund.—­From Sept. 6th to Oct. 2nd I was staying with most of my family at Portinscale near Keswick:  we returned by Barnard Castle, Rokeby, &c.”

CHAPTER VIII.

AT GREENWICH OBSERVATORY—­1866 TO 1876.

1866