1. The alidade was then aligned with the second object as well. 2. The rim of the alidade has markings for 360 degrees. 3. With skill, this sort of alidade can yield very precise measures. 4. This could be the edge of an alidade or a similar device. 5. Alidades have been made of wood, ivory, brass and other materials.6. The alidade was originally a part of many types of scientific and astronomical instrument. 7. An alidade can be seen in the lower right illustration of the Persian astrolabe above. 8. Eventually, the simple, open-sight alidade was replaced with a sighting telescope. 9. The alidade was free to rotate about a pin through the centre of the instrument. 10. Observations were typically made with an alidade , though newer versions could use a telescope.
