LESSON XXXIX. 



ON THE CIRCULATION OF THE BLOOD. 



The Blood, the fountain whence the spirits flow ; 

 The pen'rous stream that waters ev'ry part, 

 And motion, vigour, and warm life conveys 

 To tv'ry particle that moves or lives. 



ARMSTRONG. 



1 HOUGH it be common to talk familiarly of 

 the Circulation of the Bloody yet perhaps very few 

 of my young readers are well acquainted with it : 

 I shall therefore appropriate this Lesson to the 

 purpose of giving them a brief, though I hope in- 

 .telligible, description of the manner in which the 

 Circulation is performed. This important secret 

 was brought to light by William Harvey, an Eng- 

 lish physician, a little before the year 1600: and 

 when it is considered thoroughly, it will appear to 

 be one of the most stupendous works of matchless 



To form a distinct judgment of the mechanism 

 and importance of the Circulation, it will be 

 necessary to describe the structure of the arteries, 

 veins, and nerves ; and take notice of some expe- 

 riments made upon them; and then must be con- 

 o 4 sidered 



