Lower gained an estate called Traventi or Treventy in Carmarthenshire through his marriage. On the night of 17 September 1607 he was on a ship in the Bristol Channel on his way to Kidwelly to go to his estate, when he saw a comet. He recorded his observations then, and every night until 6 October and sent them to Harriot. Next time it returned it was recognised as Halley's Comet.
According to Allan Chapman, 'In the light of the above, and the information contained in Lower's letters to Harriot, two historical claims might be advanced. Firstly, Sir William Lower may have been the first to have received a telescope as a Christmas, or maybe a New Year's gift (having been observing for over a month by 6 February 1610). Secondly, “We Traventine [Trefenti] Philosophers”, who met at Lower's house to discuss Kepler and look at the moon through a telescope, might qualify as the earliest amateur astronomical society to meet in the British Isles.' (Stargazers: Copernicus, Galileo, the Telescope and the Church, p.270)