How do you determine latitude using an astrolabe?

This was really useful in determining one's location during the times when technology wasn't that advanced yet. First is that it depends as to what time of the day is it being used. If used at day, most probably at high noon, the altitude of the sun would be measured and recorded and/or remembered. Most of the times, the latitude is determined during the day since it is much easier. At night, a star of known declination will be substituted to the sun. Most of the times, the North Star is used. Then, an almanac will be utilized to determine the declination of the Sun or the star, depending on which was used. After which, the formula is applied, which is latitude = 90 degrees - measured altitude + declination.