I need to know exactly what is the content of this Bukhari's extensive work. Thought have searched the whole internet and couldn't find one.
Just curious why this precious book, authored by best known author, aren't available in English until today. Or I missed one?
Imam al-Bukhari was among the greatest hadith scholars and had a big knowledge in all the hadith sciences.
He was 18 when he started writing his famous book on hadith narrators which he called at-Tarikh al-Kabeer/al-Kabir (literally "the great history") التاريخ الكبير and he wrote it in Medina sitting close to the grave of the prophet. (The two linked wikipedia articles are my major sources)
This book as among the major sources when it comes to get information about hadith narrators in which you may find snippets of around 40K narrator biography (mentioning narrators of all categories of credibility). So it is one of the earliest books on al-Jarh wa at_Ta'adil (literally (discrediting and accrediting)) or what is also known as 'Ilm ar-Rijal (literally meaning "Knowledge of Men").
As for the content of the book:
Imam al-Bukahri quoted in this book biographies of all the hadith narrators he heard from and the qualification (accreditation and discretization) he could gain by hearing from them about narrators in the hadith they thought him or he himself could conclude.
He started the book by an introduction about the virtuous of the tribe Qur'aish, from among which Allah has chosen our beloved prophet. After that he add a short biography of the prophet, his attributes and his lineage line to the prophet Adam. Before moving to the hijri count.
The book in general is ordered alphabetically (Arabic alphabet) based on the name of the father of a narrator. But he started with those narrators which are called Muhammad as it is the name of the prophet. Then he moved to those beginning with (Alif) etc. beginning with the name of the sahaba, then those of the tabi'yn, then others. He also added those who are only (or better) known by their Kunya.
This book or these kinds of books are basically boring for the layman: As you may in best case for each narrator the following information: Full Name (including Fathers name etc.) dates of birth and death (if known), place of birth and death (if known), names of teachers and students (as far as known) and possibly a qualification of the person addressed (trustworthy, weak, etc.)
Therefore it would only make sense translating this if we would do some research on hadith sciences in a different language, but how many people would do that? In most cases when you find a hadith translation you don't even find a full chain of the hadith narrators so how would you even think about checking people you can't track as they are not mentioned? At least the above description is the case for famous books on 'ilm ar-Rijal.
This is maybe an explanation as to why these kinds of books are rather not translated. Maybe translating a book such as Siyar a'laam an-Nuabal'a of imam ad-Dhahabi would make more sense as it includes lots of reports of narrators and a bit of their attributes it is a mix of a book as described above and short biographies as we would expect.
Finally imam al-Bukhari further is the auhor of several other books on the topic like his small history (a biography collection of the sahaba) and middle history (starts with the hijarh to habashah) the small book on weak narrators (ad-Do'afaa' as-Saghir) and the great book on weak narrators (ad-Do'afaa' al-Kabeer/al-Kabir).
It is a book on Ilm ar-rijal and Jarh Wa at-Ta'dil. It is very specialized book meant for use by scholars so it is no surprise if you can't find an english translation. Translating is a very laborious task there are many many arabic books that are not translated yet.
