For information about surveying in Islam we are dependent upon two valuable treatises, together with scattered references in works on geometry and the use of the astrolabe. The first of the two treatises is called Inbāṭ al-miyāh al-khafiyya ( The Search for Hidden Waters, an edition of which was published at Hyderabad, Deccan, in 1945). It was written by a certain al-Karajī, a native of the town of al-Karaj in the Iranian province of Jibal (the Media of the Greeks). Little is known of his career; much of his life appears to have been spent in Baghdad, but eventually he returned to his native province, where he must have died after 1019, the probable date of his Search for Hidden Waters. This is an excellent manual on hydraulic engineering that includes, in addition to a chapter on levelling, a section dealing in a very practical way with the construction of qanats.

The second treatise was written by an unknown author in Iraq, probably in the second quarter of the eleventh century. It is entitled Kitāb al-ḥāwī li l-a'māl al-sultāniyya wa rusūm al-diwāniyya ( Book comprising public works and regulations for official accounting). It includes a section dealing with commercial and fiscal problems and another concerned with irrigation. This latter has been published by Claude Cahen (see Bibliography). It is divided into three parts: a brief survey of water-raising machines, a longer section on levelling instruments and their use, and a series of problems concerned with the construction and maintenance of canals, dikes and embankments. The second section is obviously of interest to us, and the third section has some instructions on quantity surveying that are probably unique in Arabic writings.

Al-Bīrūnī and other scholars wrote works on the uses of the astrolabe that include instructions for its application to geodetic surveying. As mentioned in Chapter 2, one of the meanings of the words misāḥa is 'land surveying'.