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Dakshmottara Bhitti is an instrument built
into a wall placed exactly in the North-South direction

The instrument measures the altitude or the
angular height of a celestial object when it crosses the
meridian. The meridian is the are defined by the North,
South and the Zenith. When an object crosses this arc in
the sky, halfway between its rising and setting times, it is
said to transit the meridian.

The instrument uses either the semi-circular arc built on the west facing wall, or the intersecting arcs of the east facing wall, to measure the meridian altitude of a
celestial object.

The circular arc of the west facing wall and the intersecting quadrants of the east facing wall have 90 degrees of altitude marked at the bottom of the scale and 0 degree altitude marked at its top. Altitude is measured with the help of the shadow of the rods (gnomon) ﬁxed on either sides.

The making on the scales are in units of degrees that have been further subdivided into 10 main diyisions, each with further subdivision of 3 small units, which yield a least count of 2 minutes of arc for instrument.