Comparison of underwater odors is the idea behind some mechanical searching devices now in use by the military.

VOA: special.2010.08.03

The simple mechanical pump draws water from a shallow well or nearby stream or river for use in irrigation.

VOA: standard.2009.12.18

Abdulmutallab,a 23-year-old Nigerian who had studied mechanical engineering at University College London between 2005 and 2008,was refused a visa to reenter Britain in May.

VOA: standard.2009.12.28

Meanwhile in London, the multi-million-dollar apartment where Abdulmutallab lived during his days as mechanical engineering student at University College between 2005 and 2008 continues to be searched by police forensic teams.

VOA: standard.2009.12.27