points, too, would have to be brought in, complicating the whole process to an extent that would soften the brain of any one but a calculating astronomer. In Halley’s method, the effort is to obtain two transit lines on the sun as widely apart as possible. For that purpose, the stations must differ in latitude as widely as possible. In Delisle’s method, on the contrary, the longitude becomes of primary importance. The latitude can be easily determined. Hence, in the last century, Halley’s method was almost exclusively adopted. But now we can use both; for we have better instruments and better star catalogues, and can determine longitudes by astronomical observations much more accurately than could ordinarily be done a century ago. In addition, we have now almost faultless chronometers. Besides all these means, we have, and will use to a great extent, the grand American invention of determining the longitude by the electric telegraph with an accuracy which leaves nothing to be desired. While each method requires at least two stations, a greater number would support and control each other, and allow us to take the average result of a greater number of observations. Four stations at the corners of a large quadrangle on the surface of the earth might give two sets of stations for each method. But this year the stations may be nearer a hundred. Careful preliminary studies have already determined on what portion of the earth the transit will be visible. The most available points will be turned to account for stations. We say available; for, unfortunately, much of that space is occupied by oceans, while astronomical stations must perforce be situated on firm land. Some of the best points, too, seem almost inaccessible. Still, there is a vast line of posts determined on in the northern hemisphere, and quite a number, to correspond with them, in the southern. Beginning at Alexandria, in Egypt, the line stretches northward and eastward through Palestine, Georgia, Tartary, Middle Asia, and Northern China to Yeddo, in Japan, perhaps to Honolulu, in the Sandwich Islands. Along a great part of this line, the Russian telegraphic wires will give exact longitudes, thus affording a fine field for the use of Delisle’s method. In the southern hemisphere, the line may be set down as commencing near the Cape of Good Hope, bending southeastwardly to the lately discovered Antarctic lands, passing south of Australia, then turning upwards towards the equator, and terminating at Nukahiva, in the Sandwich Islands, in the South Pacific Ocean. Along this line, at Crozet Island, at St. Paul’s, at Reunion, at Kerguelen Land—further south, if the southern summer will have sufficiently melted the snows and driven back the ice‐barrier to allow the observers to land and work—at Campbell Land, in New Caledonia, and in other places, stations will be established, between which and corresponding stations in the northern line Halley’s method may be used.