A little more than a month after the execution of his friend, Hariot is
found in his observatory at Sion taking observations of the comet of
December 1618. His valuable observations are preserved among his
mathematical papers. During the eleven years following his primitive
observations of the ' Hariot' comet of 1607, first at Ilfracombeand
later at Kidwely, great advances had been made in the science of
astronomy, chiefly in consequence of the invention of the telescope, and
the discoveries by means of it. No mathematician in Europe was probably
further advanced in this science than Hariot.

What particular discoveries belonged to him and what to Galileo, Kepler
and other contemporaries, it is very difficult to determine, since it is
now positively known that from 1609 or 1610 Hariot was a manufacturer
and dealer in lenses, or perspective glasses, as well as in perspective
trunks or telescopes; and that he was in correspondence with Kepler, and
probably with Galileo. He was easily the chief of astronomers in
England, and is known to have possessed the earliest books of Galileo
and to have sent them to his disciples, Lower and Protheroe, in Wales.
Respecting this comet of 1618, he was in correspondence with Alien and
Standish of Oxford and other scholars at home and abroad.

In 'Certain Elegant Poems, Written By Dr. [Richard] Corbel, Bishop of
Norwich. R. Cotes for Andrew Crooke, 1647, 16°- The mirth-loving Bishop,
in 'A Letter sent from Doclor Corbetto MaJler [Sir Thomas] Ailebury,
Decem. 9. 1618' [on the Comet of that year] is the following allusion to
Hariot:

_Burton_ to _Gunter_ Cants, and _Burton_ heares
From _Gunter,_ and th' Exchange both tongue & eares