Photos by Luke Abaffy for ENR The iPhone beeps when its magnetometer, in the upper right of the phone, is near metal. Related Links: Stud Find App on the iTunes Store Stud Find is an iPhone application that uses the device's built-in magnetometer to find metal studs, screws, nails and anything metallic in a wall.The iPhone's three-axis magnetometer is an instrument that measures magnetic forces. Internal Apple software uses the instrument to position the phone's 360° orientation. Stud Find uses the magnetometer as a metal detector.Testing the app on an iPhone 5, we found it works best when moved slowly
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.