On April 16, 1999, about 2200 Eastern Daylight Time, a Cessna 172M, N12469, was substantially damaged during a landing at the Flying W Airport (N14), Lumberton, New Jersey. The certificated private pilot and passenger were not injured. Visual meteorological conditions prevailed for the flight that originated from the Pennridge Airport, Perkasie, Pennsylvania. No flight plan was filed for the cross-country flight conducted under 14 CFR Part 91. The pilot stated that during his first approach to Runway 19, the airplane was too high, and he performed a go-around. During the go-around, he did not notice any fog on the runway. On the second approach, the airplane touched down at approximately 75 knots, bounced, and began to float. The airplane touched down again, in fog. Due to restricted visibility, the pilot decided not to perform an aborted landing. The airplane traveled off the end of the runway and down a ravine. The pilot further stated that he obtained a full weather briefing, and fog was not forecasted at N14. According to a Federal Aviation Administration Inspector, the airplane landed approximately 1,750 feet beyond the approach end of Runway 19, a 3,496 foot long, 75 foot wide, asphalt runway. The airplane overran the runway, and came to rest at the bottom "...of a steep hill." The Inspector further stated that the left wing spar was damaged, but there was no evidence of pre-impact mechanical malfunctions to the airplane, nor did the pilot report any. Weather was not reported at N14. The weather reported at an airport approximately 3 miles away, at 2154, was: wind calm; visibility 1/4 mile; haze; ceiling 400 feet broken; temperature 41 degrees Fahrenheit; dewpoint 30 degrees; altimeter 29.64 inches Hg. The pilot reported a total night flight experience of approximately 4 hours.