|mathematical instruments: collections of instruments of assorted kinds for performing functions in practical mathematics.
|measuring rod: an instrument used to measure distances or depths. See also gauging rod.
|measuring rods: see measuring rod.
|meridian: the plane containing the observer and both celestial poles, or containing the observer, the zenith and the pole, or, more colloquially, the north-south line at a particular position on the earth.
|meridian circle: circular scale of degrees which in use is aligned with the meridian.
|mining instruments: in this period mining instruments were principally for surveying, adapted for the special conditions of working underground in mines.
|nautical circle: generic term for a circular mathematical instrument of use in navigation, but likely to carry a range of mathematical and astronomical scales.
|nautical hemisphere: a combination of graduated arcs and circles used for navigational calculations, see article on the nautical hemisphere.
|navicula dial: type of altitude dial in the shape of a ship.
|nocturnal: instrument for finding the time at night from the orientation of the stars, see article on the nocturnal.