Xll PREFACE. 



done my best to be accurately informed by repeated 

 dissections, and .by reference to the highest authorities. 

 The latter was happily put into my power, by the 

 well-furnished library of the Alms House and of the 

 Pennsylvania Hospital; and by a private collection, 

 containing many of the most approved productions. 

 This balancing of the opinions of others with one's 

 own dissections, is, unquestionably, best suited to cor- 

 rect inferences : to follow exclusively the one- or the 

 other, is attended with great liability to error. An un- 

 due deference to approved authorities makes our opi- 

 nions habitually wavering and uncertain, from the 

 discrepance of writers among themselves; while an in- 

 sufficient attention to such means of information pro- 

 duces very serious mistakes in correctness of descrip- 

 tion, and very false ideas of scientific acquirements. 

 If we presume on our own infallibility and originali- 

 ty, we are apt to suppose ourselves possessed of sur- 

 passing skill, as floating triumphantly on an ocean of 

 discovery, as extending in every direction the bounda- 

 ries of the science and giving a new impulse to it ; 

 while, on the contrary, our faulty modes of examina- 

 tion, and neglect of competent writers, have caused us 

 to flounder ridiculously on common-place and well 

 settled points. It is thus that imaginary originality is 

 not unfrequently in an inverse proportion to the recent- 

 ness of one's induction into the science, and to the ex- 

 actness with which it has been studied. 



In the absence of knowledge, the young and enthu- 

 siastic, but heedless anatomist, is frequently prolific, 

 from the commencement, in discoveries : he makes 



