33 



to the exclusion of all other methods, to the determination of the 

 right ascensions of the stars, on the accuracy of which all the 

 fundamental problems of astronomy are based, and on which the 

 art of navigation is mainly dependent. I therefore claim for 

 Graham that he was not a mere dreamy speculative philosopher, 

 but that he applied his talents with unwearied assiduity and perse- 

 verance to the practical purposes of life, and to the promotion of 

 the welfare and happiness of mankind. - 



Probably there are none of you who have not observed that 

 in old-fashioned kitchen clocks which are furnished with a seconds 

 hand, the hand recoils at each beat of the pendulum. Though 

 somewhat of a technical matter, I will here give Dr. Pearson's 

 description of the distinction between the old "recoil escapement" 

 and Graham's "dead beat escapement," remarking in passing that 

 Dr. Pearson was himself a Cumberland man of considerable 

 reputation. 



"The recoil escapement, and which is most commonly applied 

 to ordinary clocks, impels and retards by turns, the alternate 

 motion of the pallets by its continued action on their faces, 

 occasioned by a force derived through the media of the wheels 

 and pinions from a suspended weight denominated the maintaining 

 power; while the crutch on the axis of the pallets, transmits this 

 modified force to the rod of the pendulum, and thus perpetuates 

 the vibrations. The constancy of the escapement-wheels' action 

 with the pallets in this construction, owing to their cuneiform shape, 

 is so circumstanced that the force of the returning pendulum makes 

 each pallet in its turn oppose the force derived from the maintaining 

 power, when the wheel is obliged to recede for a moment, and the 

 seconds hand inserted on its axis at the same time recoils. The 

 effect of such action is the alternate pushing and opposing of the 

 pendulum in different parts of each vibration, that an increase in 

 the maintaining power accelerates the rate of going ; and conse- 

 quently, any irregularity in the action of the wheel work, which 

 deals the force out in small portions, or any foulness from dirt or 

 thickened oil, will have an undue influence on the rate by varying 



