Remains of Astronomical Observatory at Penllergaer

Cadw's description

Summary description and reason for designation

The following provides a general description of the Scheduled Monument.

The monument consists of an observatory, a building containing celestial telescopes in which astronomical phenomena may be observed. The observatory was constructed in 1851 by John Dillwyn Llewelyn. It comprises a circular stone built telescope chamber measuring 5.5m in diameter. In the centre of this is a conical drum which supported the telescope and a rectangular chamber with vaulted roof abuts on the east side. The chamber is made out of triangular hollow brick. The use of this unusual material was probably to insulate or perhaps to decrease any vibration which would affect the operation of the telescope.

The monument is of national importance for its potential to enhance our knowledge of scientific techniques and processes. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits. The structure itself may be expected to contain archaeological information concerning chronology and building techniques.

The scheduled area comprises the remains described and areas around them within which related evidence may be expected to survive.