lOS 

 tioner had better be silent. When stating this the 

 author must be understood as expressing the con- 

 viction at which almost exclusive attention to the 

 subject, and much necessary consideration, has en- 

 abled him to arrive. It must not, however, be 

 thought that he is arrogating a power of measuring 

 the capabilities of genius ; his wish is only to declare 

 the truth as he perceives it. The intention to pub- 

 lish a work upon the teeth has not been concealed ; 

 opinions have been solicited and information sought ; 

 the author has many obligations to acknowledge; 

 all to whom he has made application have been 

 liberal in their communications ; but from no one 

 has he been able to obtain anything opposed to the 

 conclusions he has here promulgated. It may be 

 that hereafter the power of judging of the age shall 

 be extended. Pessina and the Girards thought it 

 could be done with exactitude up to an exteme 

 point, and saw a principle in the latest changes 

 which the teeth undergo. The general experience 

 in this country, however, seems to have decided that, 

 after the eighth year, there is no certainty. With 

 that decision the author is reluctantly obliged to 

 acquiesce, and even to add that certainty is not to 



