An instrument for ascertaining whether a surface is horizontal, vertical,
or at a 45* angle, consisting essentially of an encased, liquid-filled
tube containing an air bubble that moves to a center window when the
instrument is set on an even plane. Also called a spirit level. A box
level including an elongate body, plumb and level vials, and spaced
handholds having outer edges together defining first and second parallel
application planes beyond first and second face planes of the elongate
body.