PREFACE TO THE FOURTH EDITION. 



At a meeting of the Managers of the Royal Institution 

 Leld on December 12, 1825, 'the Committee appointed to 

 consider what lectures should be delivered in the Institu- 

 tion in the next session,' reported c that they had consulted 

 Mr. Faraday on the subject of engaging him to take a part 

 in the juvenile lectures proposed to be given during the 

 Christmas and Easter recesses, and they found his avoca- 

 tions were such that it would be exceedingly inconvenient 

 for him to engage in such lectures.' 



At a general monthly meeting of the members of the 

 Royal Institution, held on December 4, 1826, the Managers 

 reported 6 that they had engaged Mr. Wallis to deliver a 

 course of lectures on Astronomy, adapted to a juvenile 

 auditory, during the Christmas vacation.' 



In a report dated April 16, 1827, the Board of Visitors 

 express c their satisfaction at finding that the plan of juve- 

 nile courses of lectures has been resorted to. They feel sure 

 that the influence of the Institution cannot be extended too 



