ZyS Koikes refpeBhig Keiv Booh, 



cated the hour?, but ftruck tliem alfo. Andrew Heinlcin, 

 who trod in Ilele's footftep?, mndc fniall clocks in tlic I'mcll- 

 ing-balls which were ul'ed in his time. In the architcCrtural 

 office at Auglbiirg there is a watch, above 200 years old, 

 which flrikes the hours: it is cf)ntaincd in a crvftal cale, 

 and was made l)v Buichman. There were ftriking watclies 

 in France in the time of Louis XI. The oldelt watch in 

 England, that goes ttill prcltv well, is of the year J 540, and 

 is preferved in the palace of Hampton Court. 



VII. InvcnlKju of the fuft'c^ piiululuvi, mid fpiraJ fpring. — 

 Thefufeewas in all probability invented in England about the 

 end of the i6lh century, by whom is not known, and was 

 thence introduced into Germany. It was examined geometri- 

 cally by Varignon and De la Hire, in order to determine the 

 moft advantageous form ; which, however, docs not always 

 avail, on account of the inequality of the fpring, and therefore 

 advantage is taken of other meclianical means : of this kind is 

 the balance, by means of which the power of the fpring can 

 be adjufted, and which undoubtedly was invented in Swifler- 

 land about the beginning of the icSlh century. In the firft 

 watches with fufees, the diameter was fmall, and the box 

 large and broad. The catgut, by which it was wound up, 

 palled eight or nine times around the fufee. This made the 

 watch clunily and ill-(haped. The calgut, however, was foon 

 exchanged for a chain, which confifts of fmall plates of fleel 

 united together with great labour. In tlie middle of the 17th 

 century, Huvghens invented a better method of regulating the 

 movement of clocks. In the year 1657 he applied the pen- 

 dulum as a rc2ulati.'r to large clocks moved by weiahts; and, 

 fonie years after, recommended the balance fpriu'j for watches. 

 Before that period fome had u(ed, inltead of the Ipoon-formed 

 balance, one in the form of a ring, or employed a fmall 

 fly wheel; and Hautefeuiile ufed at lirft a fwine's briftic, and 

 then a weak, ftraight, (feci fpring, for regulating the balance. 

 In the year 1674 lluyghens eaufed a watch with a fpiral ba- 

 lance fprins to be conltructed by Turet at Paris. Dr. Hook 

 entered intoadifpute with IJuyghens in regard to this inven- 

 tion, and proved that he had invented fuel) a watch for 

 Charles II., which had the infcri])lion Robert Hook invcnil 

 1658, Tomp'ion fecit 167.J ; and that he had folicitcd a patent 

 for fuch watches in 1660, but did not obtain it till 1675. 



[ To bt cojiriuu-.tl ] 



XL VIII. Fr(,. 



