PREFACE. IX 



vision should receive more attention than is usually 

 given. 



He also begs leave to inform his patrons and the 

 public, that he has recently much enlarged his estab- 

 lishment, increased his stock of instruments, and added 

 to his machinery, tools, and fixtures; and as these 

 instruments are mostly manufactured on his own 

 premises, he is enabled to improve and simplify their 

 construction, and personally attend to the finishing, 

 proving, and packing of the same. With very few ex- 

 ceptions, they are kept ready made, and orders will be 

 executed without delay. 



