NOTES. Ixvii 



composing art, first in the decrees of Diocletian against "the old writings of 

 the Egyptians which treat of the 'chemie' of gold and silver (irepi xnt* 10 * 

 apyvpov Kai XOVGOV)." Compare my Examen crit. de 1'Hist. de la Geogra- 

 phic et de 1'Astronomie nautique, T. ii. p. 314. 



( 34S ) p. 221. Reinaud et Fave du Feu gregeois, des Feux de Guerre, ct 

 des Origines de la Poudre a Canon, in their Histoire de 1'Artillerie, T. i. 

 1845, p. 8997, 201, and 211; Piobert, Traite d'ArtiUerie, 1836, p. 25; 

 Beckmann, Technologic, S. 342. 



C 349 ) p. 221. Laplace, Precis de I'Hist. de I' Astronomic, 1821, p. 60; 

 and Sedillot, Menioire sur les Instrumens astr. des Arabes, 1841, p. 44. Also 

 Thomas Young (Lectures on Natural Philosophy and the Mechanical Arts, 

 1807, Vol. i. p. 191) does uot doubt that Ebn-Junis, at the end of the teufh 

 century, applied the pendulum to the measurement of time, but he ascribes 

 the first combination of the pendulum with wheel- work to Sanctorius, in 

 1612 (44 years before Huyghens). Respecting the very skilfully made time- 

 piece which was among the presents which Haroun Al-Raschid, or rather the 

 Caliph Abdallah, sent, two centuries before, from Persia to Charlemagne at 

 Aix-la-Chapelle, Eginhard says distinctly, that it was moved by water (horo- 

 logium ex aurichalco arte mechanica mirifice compositum, in quo duodecim 

 horarum cursus ad Clepsidram vertebatur) ; Einhardi Annales, in Pertz's 

 Monumenta Germanise Historica Scriptorum, T. i. 1826, p. 195. Compare 

 H. Mutius, de Germanorum Origine, Gestis, &c. Chronic, lib. viii. p. 5^, in 

 Pistorii Germanicorum Scriptorum, T. ii. Francof. 1584; Bouquet, Recueil 

 des Historiens des Gaules, T. v. p. 333 and 354. The hours were marked 

 by the sound of the fall of small balls, as well as by the coming forth of small 

 horsemen from as many opening doors. The manner in which the water 

 acted in such timepieces may indeed have been very different among the 

 Chaldeans, who " weighed time" (determined it by the weight of fluids), and 

 among the Greeks and the Indians in Clepsydras ; for the hydraulic clock- 

 work of Ctesibius, under Ptolemy Euergetes II. which gave the civil hours 

 throughout the year at Alexandria, according to Ideler was never known 

 under the common denomination of nXetyvSpa (Ideler's Handbuch der Chro- 

 nologie, J825, Bd. i. S. 231). According to Vitruvius's description (lib. ix. 

 cap. 4), it was a real astronomical clock, a " horologium ex aqua," a very 

 complicated "machina hydraulica," working by means of toothed wheel* 

 (versatilis tympani denticuli sequales alius alium impellentes). It is thus not 

 improbable, that the Arabians, acquainted with the accounts of improved me- 

 chanical constructions under the Roman Empire, succeeded in making an 



