EFFECTS OF INSOLATION ON A HORIZONTAL TILT OF SAINT GEORGE BASILICA'S TOWERS AT PRAGUE CASTLE

The measurement of historical monuments is one of the basic parts of engineering geodesy. The area of Prague Castle is being measured for many years, but continuous and precise measurement is being done only for a few years. One of the oldest monuments of Prague Castle is a Saint George's Basilica with its two towers. For a clear evaluation of a horizontal tilt of the towers it is necessary to know outer influences such as temperature, humidity, insolation etc. The towers are really special objects, because a horizontal tilt on the top is mostly influenced by the change of structure in the lower part. The article is focused on influence of insolation on the top of the towers during the day. For measuring of the tilt a total station was used, and a polar method for a calculation. For better understanding of horizontal tilt of the towers several measurements in various parts of the year and with different degree of insolation were compared.