This app is an accurate offline calculator for determining the horizon distance and obscured drop behind the earths curvature, which can be used to identify whether an object or land mass should be visible over a set distance from the users location and height. This has no in-app purchases and doesn't collect any personal information. You are only required to give GPS access to use the map features to show your location, no data is logged from this. --------Features:-------- - 8 inch per mile calculator, as mentioned by Samual Birley Rowbotham and Eric Dubay. - Accurate horizon and obscured drop calculator, designed by the wonderful world of Trigonometry. - Flat Earth documents: Samuel Birley Rowbotham's Zetetic Astronomy (Parallax), Eric Dubay's 200 Proofs the Earth is Not a Globe and William Carpenters 100 Proofs the Earth is Not a Globe. - Globe Earth documents: Surveying Theory and Methods, Linear Accelerators, Atmospheric Refraction and more. - Map that displays user location, user altitude and the distance to the centre crosshair, useful for finding the distance to a visible object.