DESCRIPTION OF A NEW ESCAPEMENT. 253 



tooth, fb that the tooth 1, Fig, 5, falls upon the pallet a, 

 while the tooth 5 winds the lever pallet B again into the po- 

 rtion exhibited in Fig. I. And the balance upon its return 

 receives a fecond impulfe under the circumitacces already de- 

 tailed. 



It remains only to be fhewn in what manner the middle The deren-s or 

 prone of the fork is employed. Its ufe is to fecnre the lock- ) cck,n ? P al | ets 

 ing of the pallets a and b. When the unlocking is performed anc i are veiy 

 by the aclion of either of the pallets mm, Fig. 4, the middle &&. 

 prong falls into the fmall notch in the roller ?/, which lies be- 

 tween thofe pallets ; and when the unlocking is performed, 

 and either a or b has received its tooth, the arm F renders it 

 impoffible it fliould be accidentally difengaged, becaufe that 

 arm is prevented from returning by the circular face of n, pafl 

 which it could not return at all, if the notch or excavation 

 were not made to permit to pafs at the proper time. 



Laftly, as the pallet lever B always refts againfl one of the Light preflure 

 teeth of the wheel A, the preflure againft the pallets a or /, on the detent, 

 may be rendered extremely light, fo as to deduct fcarcely any 

 thing from the momentum of the balance at unlocking. 



Fig. 3. exhibits a Ampler mode of conftruction, in which a Another con- 

 fpring is fubftituted inftcad of the pallet lever with its fpiral. ftluftion - 

 The inventor remarks, that he fhould prefer this confiruciion 

 for a clock, but that the difadvantage from the weight of the 

 fpring in different pofitions is obvious *. 



III. 



Rajiarks on the Procejfes for clarifying Liquids, By Citizen 

 Parmentier. 



(Continued from page 234.J 



NEVERTHELESS, though the ufe of the filter for water in- Filtered water Is 

 tended to be drank is of high antiquity, we mutt confefs that ™ fi P w »**«»<« 



. o ''it • deprived of gas. 



the fountains conftru&ed for this purpofe not only deprive 

 them of the earth which rendered them muddy, but likewife 



* Some account of Time-pieces and Efcapements are given in. 

 the Philofophicai Journal, Quarto Series, I. 56, 429. II. 50. III. 

 187, 342, 416. 



of ■ 



