The Coming Transit of Venus ^*

Abstract

III.

IN the previous articles various methods have been indicated by means of which we may discover the scale upon which the plan of the solar system is drawn. The last article concluded by illustrating the nature of the methods of employing a transit of Venus, as proposed by Halley. It will be noticed that this method can be utilised in the way there indicated only when Venus passes nearly across the diameter of the sun. Halley, in fact, founding his calculations upon erroneous data, was led to conclude that this would be the case in 1761. In this he erred, and another slight but important mistake having been made in his calculations, it followed that at Hudson's Bay, his northern station, the transit was invisible.