124 SEC. 3. MEASUREMENT. 



Dead Beat Clock Escapement. 

 Pin Wheel Clock Escapement. 



Zinc and Steel Compensation Pendulum as used in the West- 

 minster Great Clock. 



467a. Compensation Balance arranged in Two Groups. 



GROUP I. Earnshaw's balance with circular rim (1795), and 

 modifications thereof to the present time. 

 Earnshaw's balance. 

 Modification of do. 

 Do. do. 



Do. do., with extra adjusting screws. 



Do. do., with screws for weights. 



Do. do. do. do. 



Do. do., with screws for more minute adjust- 



ment. 



Do. do. do. do. do. 



Do. do., with double weights. 



Do. do., with variation of weights. 



Do. do., with auxiliary by Molyneux. 



Do. do., do. do. 



Modification of Molyneux's auxiliary. 

 Eifle's mercurial auxiliary: 

 Poole's auxiliary. 

 Example of recent auxiliary. 

 Do. do. do. 



Do. do. do. 



Compensation adjustment by the Astronomer Royal (Sir 

 G. B. Airy). 



GROUP II. Balances of a form distinct from Earnshaw's, from 

 Hardy (1805) to the present time. 

 Hardy's balance. 

 Arnold's do. 

 Dent's do. 



Balance with laminated arm and rim. 

 Hartnup's balance. 



Do. do. cup. 



Modification of Hartnup's balance. 

 Kullberg's flat rim balance. 



Do. double-flat rim balance. 

 Cole's balance. 



The British Horological Institute. 



468. Enlarged Model of Compensation Watch Balance. 



The British Horological Institute. 



469. Ordinary Marine Chronometer Compensation 

 Balance. The British Horological Institute. 



