22 On the Theory of 



teeth of the wheel the pallets take over, the less the teeth of the 

 wheel require to be undercut. It must not be concluded from 

 this, that the number of teeth the pallets take over can be too 

 great, for I believe the contrary to be the case, inasmuch as it is 

 more advantageous in practice to communicate the impulse to 

 the pallets at a moderate distance from their center of motion, 

 which will be the case when they take over six, seven, or eight 

 teeth ; than at a very considerable distance, as in the case when 

 they take over eleven, twelve, or thirteen teeth. 



To conclude, the great advantage of the mode of determining 

 the distance between the centers of the wheel and pallets, and 

 laying down the lines of the escapement as above described ; con- 

 sists not only in enabling the escapement to be made with the 

 least possible drop, and consequently with the least loss of power, 

 and with the action of the wheel and the friction upon each pallet 

 as equal as it can be in the dead escapement made according to 

 the usual construction with the wheel between the pallets ; but 

 on its being of general application, and equally correct whatever 

 may be the size of the wheel, the number of its teeth, or the num- 

 ber of teeth the pallets are made to take over. 



In the above, the drop of the escapement has only been men- 

 tioned incidentally, and no allowance made for that part of the 

 action of the escapement, which by clockmakers is termed the 

 drop, or beat. In the dead escapement, in common with all other 

 escapements, the drop is an unavoidable evil; and it is sufficient 

 to observe, that the more correctly in principle, and accurately in 

 execution, the escapement is made, the less will be the quantity 

 of drop requisite, and consequently the less the quantity of power 

 lost. 



The following observations have arisen out of the preceding 

 pages, and although not immediately relating to the subject of this 

 paper, are, from the relation they bear to the construction of the 

 dead escapement, here inserted : 



It has before been observed, (see note, page 3, and Fig. 4, 

 Plate II.,) that the quantity of the angle of lead of the escape- 

 ment depends upon two things ; the angle of the inclined planes, 



