the Dead Escapement. 5 



other pallet is obtained. There are several other practical methods 

 which are easy of application, but. difficult to explain." 



And again, at Nos. 1324 and 1325, page 449, (in what follows 

 the 'scape wheel is supposed made, and the original text is 

 abridged, such parts only being translated as immediately relate 

 to the laying down of the lines of the escapement,) " To draw the 

 anchor piece of the escapement," (Berthoud here supposes the 

 drawing to be made upon a brass plate, and the distance between 

 the centers already determined,) " the distance on the pillar plate 

 between the center of the scape wheel and the center of the verge 

 of the pallets must be taken* : from the center a of the anchor, see 

 Fig. 3, Plate I. (Berthoud, Vol. ii. Plate XXIII. Fig. 3 ; part of 

 Berthoud's figure is omitted, no more being drawn than immedi- 

 ately relates to the text,) the line a b must be drawn just to touch 

 the circumference, b c, of the wheel ; if from the point b, where 

 the two lines touch each other, the radius B b is drawn, it will be 

 perpendicular to b a (as may be geometrically demonstrated,) and 

 conformable to mechanical principles the action of the wheel 

 upon the pallets should be at the point b; consequently, a b is the 

 length to be given to the arm of the anchor, to enable the wheel 

 to act upon the pallets in the most favourable manner possible." 



1326. " Place the wheel in the plate with its center on the point 

 B, then place one of the points of a pair of compasses on the 

 center o of the pallets, open the compasses to the quantity ac, 

 and turn the wheel on the center B, until the front of one of its 

 teeth meets the other point of the compasses on the circle of the 

 wheel at b ; that done, keep the wheel immoveable, transport the 



* From this it would appear, that M. Berthoud's plan is to determine the 

 distance of the two centers from each other on the plate of the clock, and 

 then to adopt his escapement to those distances ; which, as the number of the 

 teeth of the wheel is regulated by the length of the pendulum, to preserve the 

 angles B 5 A, BOA, fie A, and gf A, Fig. 1. Plate I. right angles, can 

 only be done by making the pallets take over a greater or lesser number of 

 teeth, or, if necessary, by altering the size of the wheel ; or, if this cannot 

 be done for want of room or any other cause, then, and quite contrary to his 

 leading principle, the angles B 5 A and B 6 A, §c, must be increased or di- 

 minished. 



