“ Section 247 If two platforms are affixed in a wall, and one knows the width of the first and its shade and the width of the second, he may know the shade produced by the second by setting up a proportion: As is the proportion of the width of the first to its shade so is the proportion of the width of the second to its shade, for the angles of two triangles of shade with their platforms are equivalent, as both are right triangles, and both have the same angle of the sun’s height opposite the wall, with the remaining third angle being automatically equivalent as well. ”

“ Therefore, if one knows the height of the sun in degrees he also knows the angle of the reflection. Similarly, if one knows the angle of the reflection he also knows the height of the sun in degrees. Because this is so, all calculations performed on the height of the sun can also be performed on the reflection, bearing in mind the orientation of the mirrored surface, whether it is flat, diagonal, horizontal or vertical. ”

“ There is no difference whether this method is used to measure height or distance along the ground, as was seen in section 248, and the same is true here. [THIS SECTION NEEDS TO BE REVIEWED]
Section 285 All that we have spoken until now revolves around employing a quadrant standing vertically. Now I will explain how to use this tool in a horizontal orientation. If one measures a certain distance along flat ground equal to his eye level he should lay the quadrant down so that when he measures that distance the rod is at its extreme end [90 degrees] . ”