Question

what did Halley devise in the 18th century​

Answer 1

Answer:

In 1716 he devised a method for observing transits of Venus across the disk of the Sun, predicted for 1761 and 1769, in order to determine accurately, by solar parallax, the distance of Earth from the Sun.

Answer 2

Explanation:

In 1716 he devised a method for observing transits of Venus across the disk of the Sun, predicted for 1761 and 1769, in order to determine accurately, by solar parallax, the distance of Earth from the Sun.