230 Things not generally Known. 



The account of the trial of Harrison's watch is very interesting. In 

 April 1766, by desire of the Commissioners of the Board, the Lords of 

 the Admiralty delivered the watch into the custody of the Astronomer- 

 Royal, the Rev. Dr. Nevil Maskelyne. It was then placed at the Royal 

 Observatoiy at Greenwich, in a box having two different locks, fixed to 

 the floor or wainscot, with a plate of glass in the lid of the box, so that 

 it might be compared as often as convenient with the regulator and the 

 variation set down. The form observed by Mr. Harrison in winding up 

 the watch was exactly followed ; and an officer of Greenwich Hospital 

 attended every day, at a stated hour, to see the watch wound up, and 

 its comparison with the regulator entered. A key to one of the locks 

 was kept at the Hospital for the use of the officer, and the other re- 

 mained at the Observatory for the use of the Astronomer-Royal or his 

 assistant. 



The watch was then tried in various positions till the beginning of 

 July ; and from thence to the end of February following in a horizontal 

 position with its face upwards. 



The variation of the watch was then noted down, and a register was 

 kept of the barometer and thermometer; and the time of comparing 

 the same with the regulator was regularly kept, and attested by the 

 Astronomer- Royal or his assistant and such of the officers as witnessed 

 the winding up and comparison of the watch. 



Under these conditions Harrison's watch was received by the Astro- 

 nomer-Royal at the Admiralty on May 5, 1766, in the presence of Philip 

 Stephens, Esq., Secretary of the Admiralty ; Captain Baillie, of the Royal 

 Hospital, Greenwich ; and Mr. Kendal the watchmaker, who accom- 

 panied the Astronomer-Royal to Greenwich, and saw the watch started 

 and locked up in the box provided for it. The watch was then com- 

 pared with the transit clock daily, and wound up in the presence of the 

 officer of Greenwich Hospital. From May 5 to May 17 the watch was 

 kept in a horizontal position with its face upwards ; from May 18 to 

 July 6 it was tried first inclined at an angle of 20 to the horizon, with 

 the face upwards, and the hours 12, 6, 3, and 9, highest successively ; 

 then in a vertical position, with the same hours highest in order ; lastly, 

 in a horizontal position with the face downwards. From July 16, 1766, 

 to March 4, 1767, it was always kept in a horizontal position with its 

 face upwards, lying upon the same cushion, and in the same box in 

 which Mr. Harrison had kept it in the voyage to Barbadoes. 



From the observed transits of the sun over the meridian, according 

 to the time of the regulator of the Observatory, together with the at- 

 tested comparisons of Mr. Harrison's watch with the transit clock, the 

 watch was found too fast on several days as follows : 



h. m. s. 



1766. May 6 too fast 16'2 



,,17 03 51-8 



July 6 

 Aug. 6 

 Sept. 17 

 Oct. 29 

 Dec. 10 

 1767. Jan. 21 

 March 4 



14 14 



2.3 58 4 



32 15 6 



42 20 9 



54 468 



1 28-6 

 1 11 23-0 



From May 6, which was the day after the watch arrived at the Royal 

 Observatory, to March 4, 1767, there were six periods of six weeks each 

 in which the watch was tried in a horizontal position ; when the gaining 

 in these several periods was as follows : 



