Range and resolution in the Victorian kitchen at Penryn Castle

This lovely spring balance has a range up to 200 lb. I'll call that a Full Scale Deflection like I would for an analogue ammeter because the needle is actually deflected. The resolution is usually taught to be the smallest scale division: in this case +/- 1 lb. But this is a single point measurement so +/- 0.5 lb would be better. For a ruler where it is being lined up at either end, the +/- 0.5 divisions error at each end then gives you the +/- 1 scale division resolution.