Some 42 million viewers were in front of their TV sets watching the final hour of the manhunt for the Boston bomber Friday night -- nearly twice the number who usually have their sets on on a Friday, generally a light night for TV viewing. According to Nielsen, during the three hours of primetime between 8:00 p.m. and 11:00 p.m., the three major broadcast networks (ABC, CBS and NBC) and the three major cable news networks (CNN, Fox News, and MSNBC) together averaged 35.9 million viewers versus 21.9 million for a typical Friday. NBC, usually the lowest-rated of the broadcast networks on Friday nights, saw its audience nearly quadruple for its coverage of the manhunt. CNN, whose ratings have been in freefall in recent years -- and the brunt of scathing criticism for its inaccurate reporting following the bombings -- drew its best ratings in a decade -- save for political coverage.