Question

Statement I: Open cross staff is used for setting out right angle at a given point on the chain line.
Statement II: French cross staff can set angle at 45${}^o$ and 135${}^o$ other than 90${}^o$ at a given point on the chain line.
The correct combination of the above statement is

• A. I-False II-True
• B. I-False, II-False
• C. I-True, II-True
• D. I-True, II-False

Answer 1

The correct option is C I-True, II-True

Cross-staffs are of following types:
(i) Open cross-staff:
It is used for
* Finding the foot of a perpendicular offset.
* Setting out a right angle at a point of the chain line.
(ii) French cross-staff
It is used for setting out right angles,
* It has the advantages that the lines can also be set out at angles of 45${}^o$ and 135${}^o$. In that respect, a french cross-staff is superior to an open cross staff.
(ii) Adjustable cross-staff
It is used to take off sets and to set out any desired angle from the chain line.