Explain various instruments used for Tacheometer.

TACHEOMETER

 A tacheometer is a transit theodolite having a stadia telescope fitted with two horizontal hairs called Stadia hairs(stadia lines) in addition to the usual cross hairs. The stadia diaphragm has three horizontal hairs: a central horizontal hair, and upper and lower stadia hairs. The upper and lower stadia hairs are equidistant from the central horizontal hairs.

•  The value of multyplying constant should be 100.
•  The value of additive constant should be zero.
•  The telescope is fitted with analytic lens.
•  The magnification of telescope should be 20 to 80 diameter.
• Magnifying power of eye piece is kept high.

 Stadia rods/Levelli....Show More

TACHEOMETER

 A tacheometer is a transit theodolite having a stadia telescope fitted with two horizontal hairs called Stadia hairs(stadia lines) in addition to the usual cross hairs. The stadia diaphragm has three horizontal hairs: a central horizontal hair, and upper and lower stadia hairs. The upper and lower stadia hairs are equidistant from the central horizontal hairs.

fig:  Tacheometer

 Characteristics of tacheometer:

•  The value of multyplying constant should be 100.
•  The value of additive constant should be zero.
•  The telescope is fitted with analytic lens.
•  The magnification of telescope should be 20 to 80 diameter.
• Magnifying power of eye piece is kept high.

 Stadia rods/Levelling staffs:

 The stadia rod is about 3m to 5 m long. For short sights, an ordinary levelling staffs may be used. For long sights, special staff called stadia rods is generally used.