





Ganka Kamisheva [1], Alexander Kamishev [2] 
Abstract: Distance measuring is a human practice from the antiquity. There are many different methods (direct, and indirect). Access to the measuring area is requirement for direct method. Indirect methods will be discussed in this work only.
The area that is out of reach has been measured by trigonometrical method. Thales described this method for the first time in 6 century before Christ. He described how to calculate the ship remoteness from the seaside. Two observers from the lànd measured distance between them (L) and angles between L and ship lines (A and B). In that case D is an altitude of isosceles triangle. It is equal D = L/(1/tg A + 1/tg B). Thales described determination of the altitude of pyramids in Egypt too.
We use measuring units and their transformation to evaluate circumference of the Earth because some Bulgarian sources show its different value.
Key words: Methods, Measuring, Distances, History
Created: 1 August 2016
Updated: 21 January 2017