Prob. IX. To find the Antœci, Periœci, and Antipodes to any given place.
Bring the given place to the meridian; and having found its latitude, count the same number of degrees on the meridian from the equator towards the contrary Pole, and that will give the place of the Antœci. The globe being still in the same position, set the hour index to XII at noon, then turn the globe about ’till the index points to the lower XII; the place which then lies under the meridian, having the same latitude with the given place, is the Periœci required. As the globe now stands, the Antipodes of the given place are under the same point of the meridian, that its Antœci stood before: Or, if you reckon 180 degrees upon the meridian from the given place, that point will be the Antipodes. Let the given place be London, in the latitude of 51½ degrees North, that place which lies under the same meridian and the latitude 51½ degrees South, is the Antœci; that which lies in the same parallel with London, and 180 degrees of longitude from it, is the Periœci, and the Antipodes is the place whose longitude from London is 180 degrees, and latitude 51½ degrees South.
Prob. X. The Hour of the Day at one place being given; to find the correspondent Hour (or what o’Clock it is at that time) in any other place.
The difference of time betwixt two places is the same with their difference of longitude; wherefore having found their difference of longitude, reduced into time (by allowing one hour for every 15 degrees, &c.) and if the place where the hour is required lies (Easterly/Westerly) from the place where the hour is given, (add/subtract) the difference of longitude reduced into time (to/from) the hour given; and the sum or remainder will accordingly be the hour required. Or,
Having brought the place at which the hour is given to the meridian, set the hour index to the given hour; then turn the globe about until the place where the hour is required comes to the meridian, and the index will point out the hour at the said place.
Thus when it is Noon at London, it is
| H. | M. | ||||
|---|---|---|---|---|---|
| At |  | Rome | 0 | 52 | P. M. |
| Constantinople | 2 | 07 | P. M. | ||
| Vera-Cruz | 5 | 30 | A. M. | ||
| Pekin in China | 7 | 50 | P. M. | ||