3."A Practical Essay on 3."A Practical Essay on
   Cancer,” by C. T. Johnson.  Cancer,” by C. T. Johnson.

4."The Sharper Detected 4."The Sharper Detected
   and Exposed,” by R. Houdin. and Exposed,” by R. Houdin.

5."The Sign of the Four,” 5."The Sign of the Four,”
    by A. Conan Doyle. by A. Conan Doyle.

6."Cancer, a New Method of 6."Legal Chemistry:  A
   Treatment,” by W. H. Guide to the Detection of
   Broadbent.  Poisons, Examinations of
                                      Stains, etc., as Applied to
                                      Chemical Jurisprudence.” 
                                      From the French of A. Naquet
                                      by J. P. Battershall, Nat.Sc.D.

7."Reports of Trials for 7."Traite Pratique des
   Murder by Poisoning,” Maladies Cancerences,”
   by G. L. Browne and C. par H. Lebert. 
   G. Stewart.

8."A Practical Treatise on 8."A Practical Treatise on
   Poisons,” by O. H. Costill.  Poisons,” by O. H. Costill.

9."Poisons, Their Effects 9."A Treatise on Poisons in
   and Detection,” by Alexander Relation to Medical
   Wynter Blyth.  Jurisprudence, Physiology,
                                      and the Practice of Physic,”
                                      by R. Christison,M.D., F.R.S.E.

10."Poisons, Their Effects 10."Poisons, Their Effects
    and Detection,” by Alexander and Detection,” by Alexander
    Wynter Blyth.  Wynter Blyth.

“There, do you wonder that the perusal of that list excited me? 
Come, now, before I go any further, tell me what you make of it,
Doc,” and he passed it to me.

“There seems to me to be a singular unanimity of purpose existing between these two men,” I said; “not only as regards the subject-matter of their reading, but in no less than six cases they have both perused the same volume.  This never happened by chance.  Clearly, they are acquaintances, and are working together toward some common end.  I should think it very likely, judging from their interest in cancers and toxicology, that they were medical students.  Numbers four and five don’t exactly seem to strengthen my medical hypothesis, but they are only two out of the ten.  That’s about all I can make out of it;” and I returned the list to him.