Page:Popular Science Monthly Volume 6.djvu/237

Rh, is perfectly impartial, and whose observations take the form of an instantaneous but permanent record.

Preparations of the most elaborate kind have been made by the leading nations of the world for this event for years beforehand; and the side of our globe, turned sunward on the important day, will be occupied by over seventy astronomical stations. As an amicable interchange of results is to be counted on, the means for trying every method here alluded to, as well as others, will be of the amplest kind; and there is every reason to hope that they will give us a value of the sun's distance, accurate in proportion to the knowledge, energy, and skill, which have gone to furnish them.

From what has been already said, it must be abundantly plain that, unlike an eclipse of the sun, which is total over a very small area, the transit of Venus will be visible over a whole hemisphere of the earth—over more, in fact, since the rotation of our globe brings new countries into the sunlight during the hours the passage lasts, and some will see it begin who will not see it close; others see it close

who do not see it begin. While the transit continues, wherever the sun can be seen, there Venus will be seen on it, with the exception of the few minutes of entry, when those on the extreme left of the earth will see her before the rest, and the corresponding time of exit.

We do not see the phenomena at all in the United States, because all America is on the night side of the earth at the time, a fact made plainer by the accompanying diagrams, showing the earth as it is poised in space, viewed from the sun; first at the beginning of the