Professor Hoffmann is often mentioned in discussions of disclosures of magic secrets. For example, Jonathan Townsend mentioned Hoffmann recently in another thread.
One of the main points of interest about Hoffmanns descriptions of magic secrets is that in many cases they first appeared in periodicals directed primarily toward boys and girls (mainly boys). The chief examples of those periodicals (as to Hoffmann) were The Young Gentlemans Magazine (which later became Every Boys Magazine) and The Boys Own Paper.
I thought Id briefly mention at this time a few other nineteenth-century examples of magicians who described magic secrets in periodicals for children.
George Forrest (of The Boy's Own Book fame, not sure off hand whether he was a performer) contributed a series of three articles, entitled Conjuring, to Routledges Magazine for Boys, mainly in 1865. (I think the first installment probably was published in 1864.)
In the same periodical, Stodares Fly-Notes; or, Conjuring Made Easy for Juvenile Amateurs was serialized in Routledges Magazine for Boys during 1866. Actually, I think it is likely that the serialization began in late 1865, because the first installment appeared in the January 1866 monthly issue, which was probably published in 1865.
(A little parenthetical note: Modern English Biography, by Frederic Boase (Truro, 1921), Volume VI, columns 504 and 505, contains what I believe is a pretty good summary of the title changes of the periodical just mentioned. By the time the serialization of Modern Magic began, the title was The Young Gentlemans Magazine. It changed to Every Boys Magazine during that serialization.)
The only other serialization I want to mention in this post is that of Lessons in Magic, by P.C.H. (Henry Hatton). The first installment of Lessons in Magic appeared in the March 1865 issue of Our Young Folks (page 189). The effects explained included The Sphinx (in the November 1866 issue of Our Young Folks). The illusion known as Proteus was explained in the same issue.
All of the foregoing serializations had concluded before Professor Hoffmann even met with Edmund Routledge to discuss the work that became Modern Magic (which was serialized beginning in 1872 and ending in 1876).
I believe that nearly all of the serializations mentioned above can be located on Google Books.