346 SECTION MECHANICS. 



the workman has greatly advanced, science has not kept pace with it, 

 and pocket chronometers are fast giving place to the best form of lever 

 escapement that invented by Mudge and strangely enough abandoned 

 by Mudge himself in favour of a much inferior escapement. 



The model of the balance shown by Mr. Dent differs in form from 

 that in general use, the ordinary form being that of a ring or rim com- 

 posed of a lamina of brass and steel melted together and so propor- 

 tioned to each other that when cut open the rim contracts in heat, 

 thereby decreasing its diameter and expands in cold, which increases 

 its diameter, and thus compensating for the error which is principally 

 in the balance spring, caused by its elongation and loss of elastic force 

 in heat, and its greater resistance when cold ; and it may be of impor- 

 tance to those who wear watches without compensation balance to 

 know on the authority of the Astronomer Royal, that for every difference 

 of ten degrees in temperature there is a difference in twenty-four hours 

 of one minute in the time of these watches. 



Unfortunately for the scientific progress of watchmaking the trade 

 spirit so predominates that scientific men have not of late years 

 devoted themselves to its study as might have been expected from the 

 nature of the great interest attached to it, otherwise we might have 

 been further advanced than we are at present. 



But what I want to say is this, and I am glad of the opportunity of 

 saying it here, the mode of testing and purchasing chronometers for 

 the navy is not satisfactory, and is not calculated to encourage the men 

 by whose efforts alone we can hope for a higher standard of excellence. 

 In the first place the prices paid by the Government are too small to 

 tempt such men from their ordinary pursuits to make the long and 

 careful experiments necessary for perfecting any new form of balance 

 or even improving upon old forms, and secondly, chronometers are sent 

 to Greenwich by scores from all the little towns in the kingdom, bear- 

 ing names of men who perhaps have never seen the instruments to 

 which they are affixed, but if purchased they are " chronometer makers 

 to the Admiralty," the chronometers being made in London. 



I think this should not be, and that some means should be adopted 

 to insure that "chronometer maker to the Admiralty" be a distinction 

 worth coveting and competing for, and not merely to be used as a 

 trade "puff" by men who know nothing of chronometers. 



