Following the discussion in class, it sparks a thought that actually we do not need an arc to read a sundial. Essentially the shadow of the sun always falls at a different length anyway. I drew another idea where a sundial can be read by the length of the shadow or the y position where the shadow end falls on a grid. This sundial can be a horizontal one with a perpendicular gnomon and it will be tilted by the (90 deg - latitude) of one's location (if facing the north).