POPULAE LECTUEES 



ON 



SCIENTIFIC SUBJECTS. 



/ " 



H. 'hELMHOLTZ, 



PROFESSOR OF PHYSIC:J IN THE UNIVEIISITX OF BERLIN. 



TEANSLATED BY 



E. ATKINSON, Pu.D. F.C.S. 



PBOPESSOR OB- EXPERIMENTAL SCIENCE, STAFF COLLEGE. 



WITH AN INTRODUCTION 



BT 



. PROFESSOR TYNDALL. 



NEW YOEK: 

 D. APPLETON AND COMPANY, 



549 & 551 BROADWAY. 

 1873. 



