Charles Grandison Finney

Charles Grandison Finney (1792-1875) was an American Presbyterian minister and leader in the Second Great Awakening in the USA. He has been called the Father of Modern Revivalism.
Together with other evangelical leaders he promoted social reforms such as abolition of slavery and equal education for women and African Americans. He taught at Oberlin College, Ohio and became their second president form 1851 to 1866.

In V. Raymond Edman’s book They Found the Secret(still available on Amazon) there is chapter of over 10 pages given to how he found the secret. Edman’s begins by saying that Charles’ conversion was sudden, starling, dramatic and dynamic. Edman gives Charles’ own account of what happened around the date of 18th October 1821 - it started on the Sunday and continued through to the Thursday.

In the brief notes I have included from the book it says that Finney’s revival ministry in Rochester, New York, in one year 100,000 came to the saving knowledge of the Lord. Also that there was a falling off of crime and the jail was nearly empty for years afterwards.

Daniel Nash(1775-1831) worked behind the scenes for Charles. Daniel would precede Charles arrival in a city. He would check into a boarding house and begin to pray fervently for the release of the Holy Spirit onto the forthcoming meeting(s). He would pray sometimes for days, even weeks until he felt the spiritual atmosphere was prepared. He would then invite Charles to come. He rarely attended the meetings instead he would be on his knees in prayer.
4 months after Daniel’s death Charles left his itinerate revival meetings to pastor a church.

My other source is Wikipedia.