INFLUENCE ON THE HUMAN SYSTEI\r. 115 



the habitual drunkard would by alcohol. Of 

 course, for the sake of the argument, I suppose 

 the habitual smoker to exceed the limits permitted 

 by his cerebral organisation. This is a point 

 which each individual must learn by experience 

 alone. Nihil nimis must be the motto and guide 

 of all who would enjoy their powers to the end. 

 If your horse can trot twenty miles per hour, 

 always keep him at ten, if you wish him to last; 

 and so in all things appertaining to human exer- 

 tion and enjoyment, keep below rather than at the 

 mark — let a little appetite always remain unsatis- 

 fied, if you would preserve your functional activity 

 to the utmost. 



By the Turkish and Indian pipes, narguileh 

 and hookah, in which the smoke is made to pass 

 through perfumed water and a tube of great 

 length, it is thought that a large portion of the 

 poisonous vapours is arrested ; it may be so to 

 an extent proportionate to the length of the tube ; 

 but the latter I found just as rapidly fouled as 

 any others, even to the very tip of the mouth- 

 piece, with the disgusting and tarry oil before 

 mentioned. 



I2 



