INFLUENCE OF SUSPENSION ON WATCH. 361 



time when carried in the pocket, or laid on a soft 

 pillow, will go at a different rate if laid on a marble 

 slab, or on a hard board. These variations of rate 

 arc not due to any imperfections of the balance- 

 wheel or mechanism of the watch or chronometer, 

 but arise from reaction clue to the motion of the 

 moving parts. A well-balanced watch will go 

 equally well whether supported in a vertical or 

 horizontal plane ; and a well-made watch will, I 

 believe, not be subject to uncertainty of above a 

 quarter of a second per day, if carried about in the 

 pocket all day and put under the pillow at night. 

 This I can testify from experience of a good 

 pocket-watch which I have tried now for nearly 

 two years ; indeed, a good pocket-watch, if well 

 treated, is comparable in its performances with 

 the best marine chronometer. 



I was very much struck some time ago by a 

 remark made to me by Mr. Archibald Smith, of 

 Jordan Hill, regarding a demi-chronometer, with 

 detached lever and compensated balance, presented 

 to him by the Admiralty for the voluntary assist- 

 ance he had given them in working out methods 



