Noiiccs reffeBmg Nc"u> Booh. 1 79 



period that attempts were made to conftru£t hour-glaffes ia 

 an elegant and ingenious manner. Many of them are de- 

 fcribed by Francis de Lanis, as well as by Scliott and Oza- 

 11am. Rivaiilt employed fuch fand-glafles for aftronomical 

 obfervations; and likewife Tycho Brahe, who ufed alfo 

 clorks conftriiftcd with quiekfilvcr. 



IV. IngeriioKS luater-clocks arid other mi chines, the moving 

 frincLplc of ivhich ivas different from that of our common clocks 

 that go by ivhecl-iuork. — [Jnder this liead the author fpeaks 

 of the machine which king Gonebaud received as a prefent 

 from Theodoric king of the Goths. He aives alfo a defcrip- 

 tion of the before-mentioned t lock fent by Harun al Rafchid 

 to Charlemagne. At that period the eaftern princes prefent- 

 ed clocks to the weUern ; at prefent this mode is reverfed. 

 This chapter contains alfo a dcfcription of fome other inge- 

 nious clocks from Schott, Kircher, Ozanam, Martinelli and 

 de Lanis ; alfo Perranlt's pendulum-clock, which was moved 

 by water, and a Chinefe one w hich Y-Hang caufed to be 

 conftrufted. 



[To be continued] 



Tratte Elementaire dtt Calcul D'lff'ercnt'tel et Integral, ^c. 

 An Elementary Treatife on the Differential and Integral 

 Calculus, preceded by fome Reflcftions on the Method of 

 teaching the Mathematics, and appreciating in Examina- 

 tions the Knowledge of thofe who have lludied them. 

 By S. F. Lacroix. Paris, An. 10. 



THE author of this work is well known by his large trea- 

 tife on the Differential and Integral Calculus, in three vols, 

 quarto, in which he has given a complete view of every 

 thing taught on the fubje£t, and which ought to be ftudied 

 by thofe who are defirous of enlarging the boundaries of this 

 fcience. The time devoted, ufually, to a courfe of analyfis 

 being far from fufficient to follow with the proper atten- 

 tion fo many objects, the author found it nccelfary to make 

 a feledion. This publication, however, is not merely an 

 extradl from the abf)ve large work ; it is a new treatife, 

 which cannot fail of interelting thofe who are in the pof- 

 fedion of the other. It is founded on the fame principles, 

 and will form an excellent introduction to the (ludy of the 

 more learned works. 



Vilements of Cheviiflry. By J, MuRiiAV, LcHurcr on Che- 

 m'lllry. Materia Medica, and Pharynacy. 2 vols. iJvp. 

 Edinburgh 1801. 

 TIII.S work will be found very ufcful to the chemical ftu- 



Jent. The author has given a corrccl view of the prefent 

 Ma ftatc 



