Gregorii posthuma, or, Certain learned tracts written by John Gregorie. Together with a short account of the author's life and elegies on his much-lamented death published by J.G.

Of the Axel and Poles of the Globe and of the Hour Circle.

FRom the North and South Ends of this Meridian a strong Wyer of Brass or Iron is drawn, or supposed to bee drawn (for the Artificers do not alwaies draw it quite through) by the Center of the Globe representing the Axel of the Earth. The North End whereof standeth for the North, the South End for the South Pole of the Earth. Upon the North End, a small Circle of Brass is set, and divided into two equal parts, and each of them into twelv, that is, twentie four in all. This Circle is the onelie one above the Globe, which is not imagined upon the Earth, but is there placed to shew the hour of the daie and night, in anie place where the Daie and night exceed not 24 hours: there∣fore it is called Cyclus Horarius. The Hour Circle, for which purpose it hath a little Brass pin turning about upon the Pole, and pointing to the several hours, which therefore is called the Index Horarius.

The small Circle is framed upon this ground, that in the Diurnal Motion of the Heaven 15 Degrees of the Equino∣ctial rise up in the space of everie one hour, that is 360 De∣grees, or the whole Circle in the space of 24. So that the Cyclus Horarius is to bee framed to that Compass, as that everie 24^th part of it, or one hour is to bear proportion to 15 Degrees of the Equator below it. And so in turning the Globe about, one may perceiv, that while the Pin is moved from anie one hour to another, just 15 Degrees of the Equi∣noctial will rise up above the Horizon upon one side, and as manie more go down below it on the other side. But this Circle is not much for the Geographer's use.