diagram showing the exact position of Venus on the
Sun's disc, which corresponded in every respect with Horrox's
observation; he also estimated the diameter of the planet to be 7/200
that of the Sun, which when calculated gives one minute three seconds;
Horrox having found it to be one minute twelve seconds. This transit of
Venus is remarkable as having been the first ever observed of which
there is any record, and for this we are indebted to the genius of
Horrox, who by a series of calculations, displaying a wonderfully
accurate knowledge of mathematics, was enabled to predict the occurrence
of the phenomenon on the very day, and almost at the hour it appeared,
and of which he and his friend Crabtree were the only observers.

Having thought it desirable to write an account of the transit, Horrox
prepared an elegant Latin treatise, entitled 'Venus in Sole
Visa'--'Venus seen in the Sun;' but not knowing what steps to take with
regard to its publication, he requested Crabtree to communicate with his
bookseller and obtain his advice on the matter.

In the meantime Horrox returned to Toxteth, and arranged to fulfil a
long-promised visit to Crabtree, which he looked forward to with much
pleasure, as it would afford him an opportunity of discussing with his
friend many matters of interest to both. This visit was frustrated in a
manner altogether unexpected. For we read that Horrox was seized with a
sudden and severe illness, the nature of which is not known, and that
his death occurred on the day previous to that of his intended visit to
his friend at Broughton. He expired on January 3, 1641, when in the 23rd
year of his age.

His death was a great grief to Crabtree, who, in one of his letters,
describes it as 'an irreparable loss:' and it is believed that he only
survived him a few years.[5] Of the papers left by Horrox, only a few
have been preserved, and these were discovered in Crabtree's house after
his death. Among them was his treatise on the transit of Venus which,
with other papers, was purchased by Dr. Worthington, Fellow of Emmanuel
College, Cambridge, a man of learning, who was capable of appreciating
their value. Ultimately, the treatise fell into the possession of
Hevelius, a celebrated German astronomer, who published it along with a
dissertation of his own, describing a transit of Mercury.

Horrox did not live to see any of his writings published, nor was any
monument erected to his memory until nearly two