XI. TIME. 123 



No. 8. A compensation bar is formed, as in No. 5, by brass being melted 

 upon steel, and this bending upwards or downwards, with any change of 

 temperature, tilts the weights carried by the staples towards or away from 

 the axis of motion. But the staples are themselves compensation pieces, and 

 they lift the weights higher with any increase, and depress them with any 

 decrease of temperature, and in this manner increase the rate at which 

 they approach the axis of motion, and diminish the rate at which they recede 

 from it. (Dent's patent balance.) 



No. 9. A balance of nearly the same form as No. 6, but the section of its 

 rim is somewhat in the shape of a prism ; the form of the rim offers less re- 

 sistance to the motion of the compensation weight inward than outward. 

 (Dent's registered balance.) 



No. 10. A balance similar to No. 5 is mounted upon the arm of a balance 

 similar to No. 6. With any increase of temperature, the first balance can 

 assist the second, but with any decrease of temperature its motion is checked. 

 The whole combination, therefore, is more effective in the heat than in the 

 cold. (Glover's form.) 



No. 11. An experimental balance, contrived for the purpose of removing 

 weight from the centre, both with an increase and decrease of temperature. 

 (Wetherill's form.) 



No. 12. An auxiliary compensation is added to a balance similar in form 

 to No. 6. The auxiliary consists of two double compensation pieces, and the 

 effect is to carry weight towards the axis of motion, both for an increase and 

 decrease of temperature. The effect of the main compensation weights is 

 therefore increased in the heat and diminished in the cold. (Dent's balance.) 



No. 13. A balance of similar design to No. 8, but arranged so that tho 

 secondary compensation can be altered with greater facility. (Dent's 

 balance.) 



No. 14. A balance having the same general operation as No. 8, but the 

 effect is obtained by straight bars only. The secondary compensation can 

 also be altered without inconveniently disturbing the main compensation, and 

 both without producing any great alteration in the time of the chronometer. 

 (Dent's balance.) 



467. Drawings of Compensation Balances, Escape- 

 ments, and other appliances connected with the construction of 

 Clocks and Watches. The British Horological Institute. 



Lever Escape Wheel. 



Lever Escapement. 



Double Roller Lever Escapement. 



Two Pin Lever Escapement. 



Chronometer Escapement. 



Duplex Escapement. 



Club Tooth Lever Escapement. 



Verge Escapement. 



Horizontal Escapement. 



Double Roller Lever Escapement with Compensation Balance. 



Marine Chronometer Escapement. 



Compensation Adjustment by Sir G. B. Airy, Astronomer Royal, 

 1875. 



Double Three-legged Gravity Escapement as used in the West- 

 minster Great Clock. 



