the Dead Escapement: 21 



There is a construction of the dead escapement, in which the 

 point of action of the wheel upon the rests may be at right angles 

 to the centers on both pallets, and consequently the rests at equal 

 distances from the center of motion of the pallets ; but in that 

 case the impulse upon the two pallets is not at an equal distance 

 from their center, but the thickness of a pallet further from the 

 center upon one pallet, than upon the other. See Fig. 2, Plate II. 

 The impulse upon the inclined planes of the pallets being at an 

 unequal distance from their center, is a most serious defect, and 

 the cause that this construction of pallets is no longer employed*. 



Another advantage resulting from the mode of placing the center 

 of action of the pallets as above proposed, is that the wheel will 

 require to be undercut the least possible quantity ; for if the center 

 of action of the pallet is raised above its proper center of motion, 

 it will cause the wheel to be more undercut than it need otherwise 

 have been, to free the pallet upon the inner rest on which the 

 wheel acts, otherwise the point of intersection of the inclined 

 plane, and rest of the pallet will cause the wheel to recoil, by 

 coming into contact with the face of the tooth of the wheel : and 

 if the center of the pallets is brought lower than the proper center 

 of motion, it will cause the wheel to be more undercut to free the 

 pallet upon the outer rest on which the wheel acts, otherwise the 

 action of that rest will occasion the wheel to recoil, (though the 

 effect is very much less considerable in this case than in the 

 former,) consequently, the proper centre of motion of the pallets is 

 the most advantageous to the shape of the teeth of the wheel : 

 for, as has been before noticed, the less the teeth of the wheel 

 are undercut, the shorter, and consequently the stronger, they 

 will be. It may be further observed, supposing the center of the 

 pallets to be in its proper place, that the greater the number of the 



* It has been before noticed tbat I. A. Le Pautie, in his Traite d'Horlo- 

 gerie, 4to. Paris, 1167, page 188, mentions, that Mr. Graham made his dead 

 escapement for clocks with the rests at equal distance from the center of mo- 

 tion of the pallets, and has so represented them in the plates to his work. 



I do not recollect ever having seen a clock of Mr. Graham's with the pallet 

 made in this manner, though I have seen such applied in old clocks. 



