The types of compass that are used commonly are: (i) prismatic compass; and (ii) surveyor compass.
The essential parts of both type are:
(i) A magnetic needle,
(ii) A graduated circle,
(iii) A line of sight, and
(iv) A box to house them.
There are some differences in the essential parts of the two type of compass. The construction of the two types of compass is explained and the difference in them is pointed out in this article.