"To this river the Governor gave the name of Nepean (after Captain
Nepean, of the New South Wales corps). The distance of the part of the
river which was first hit upon from the sea coast is about thirty-nine
miles, in a direct line, almost due west."

In December, 1789, Governor Phillip dispatched a party, under Lieutenant
Dawes, of the Marines, accompanied by Lieutenant Johnson and Mr. Lowes,
to cross the Nepean and try to penetrate the range beyond. They
discovered a ford in the river, and crossing, proceeded in a westerly
direction. So rugged and difficult, however, did they find the country
that in three days they had only covered fifteen miles. At a bill that
they called Mount Twiss they turned back, having penetrated fifty-four
miles in a direct line from the sea coast.

In August, 1790, Messrs. Tench, Dawes, and Morgan explored south and west
of Rose Hill. They struck the Nepean higher up, nearer its source than on
the former occasion, and remained out seven days, penetrating to a
considerable distance in a south-west direction. Near the end of the same
month, the same party made an excursion to the north-west of Rose Hill,
and traced the Nepean to where it was first discovered by Tench's party
in 1789.

In April, 1791, Governor Phillip, attended by a large company, numbering
in all twenty-one persons, including two natives, set out on an
expedition from Rose Hill to determine the identity, or not, of the
Nepean and the Hawkesbury. On the 12th of the month they struck the
river, and followed it down for some distance, but did not accomplish the
object they had in view.