Origin of "The Scoop"

"The journalistic sense of 'news published before a rival' is first recorded 1874, American English, from earlier commercial slang sense of 'appropriate so as to exclude competitors' (c.1850)."
http://etymonline.com/index.php?term=scoop&allowed_in_frame=0

This source confirms the date and suspected meaning discussed in class. I'm still curious about the story behind "the scoop." Do you know of any other explanations?