4*^4 Notices rcfpecilng New Booh, 



cherter. By Mr. John Dillon. — Appendix. T. Kxplanatiort 

 oF a Roman Infcnption found in Caitle (ieid, Mancheller. 

 By Mr. Thomas Barritt : with a Note on the fame Subject by 

 Dr. Hohiie. — II. Note to Mr, VV. Henry's Paper on Heat. 



Ausfhrliche Gejclnchte <ier TheoreUfch Prakfifchen Uhrma- 

 cberkunji,&'c A Hiftoj-v ot Clock- and Watch-niaking, 

 both Theoretical and Pra<htical, fince the earlieit Method 

 of dividing the Day to the find of the i8th Century. By 

 I. II. MoRiz PopEE, 1801. 8vo. 564. p. 8. 



[Coiunued from p 179] 



V. The invention of clocks moved by wheels and weights, 

 and their progrt/Jive improvement (ill the middle oflhej^ven- 

 teenth century. — Tlie invention of clocks moved by wheels 

 and weights, as well as the period of the invention, is totally 

 unknown. The author, however, hascolieded the refearchesof 

 learned men on this fuhjecl, and refutes the opinion of thofe 

 who make the invention to be not old'.r than the 14th century. 

 The invention, however, was not very great, as the more per- 

 fect water-clocks were before that period fnrnilhed with 

 wheels, fo that the only improvement was the fubftuution of 

 afolid botly to a6t as a moving vveio;ht inftead of vv.iter. The 

 principal point was to produce uniformity in the ac-tion of 

 thefe weights ; and. in this refpecl the firrt clocks moved by 

 weights were deficient till the time of Huyghens. It is not 

 therefore to be wondered at, that the application of weights 

 to clocks as a moving power fhould excite fo little attention 

 as to be fcarcely thought worth notice by cotemporary writ- 

 ers : water and fand were indeed more convenient than a 

 folid weight, which requires too much room for its motion. 

 The author is of opinion that the origin of clocks with weights 

 is as old as the nth century, and adduces verv probable 

 grounds in fupport of it ; but it is not properly afcertaincd, 

 whether the inventor was an European or a Saracen. The 

 oldeft complete clock moved by weights, of which there is 

 any certain teftimony, is th.it fent by the fultan of Egypt iii 

 the year 1232 to the emperor Frederic II, the value of which 

 was at that time ellimate! at 5000 ducats. In the 13th cen- 

 tury many of the church-Ueeples in Italy were furniihed 

 with clocks moved by weights that ftruck the hours. About 

 the fame time the well-knowti clock-houfe at Wcftminfter- 

 hall was furniflied with a clock that ilruck the hours; the ex- 

 penfe of which was defrayed by a fine iinpofed on one of 

 the judges. The clock moved bv weights of the abbot 

 Richard of VVallingford, which by many has been confidcred 

 as the oldeft, was coaftru<^lcd in the 14th ceutury, h\ th© 

 6 year 



