PRELIMINARY EXAMINATION
is made into the patentability of an invention by personal search at the Patent Office, among the models of the patents pertaining to the class to which the improvement relates. For this special search, and a report in writing, a fee of $5 is charged. This search is made by a corps of examiner of long experience.
Inventors who employ us are not required to incur the cost of a preliminary examination. But it is advised in doubtful cases.