OPERATION VI. To know what a Clock 'tis at any time, in any place of the World.
THere is no Operation perchance in the whole Treatise,* 1.1 more diverting and pleasant than this; nor scarce any more readily perform'd after a very little Reflection, even in the most difficult Cases. For having Compos'd your Globe, if it be then 12. a Clock with you, the standing Hour Circles or Me∣ridians already described, will (by the Common or little Figures which lye within or upon the Roman ones, that surround the Po∣lar Circles,) shew you exactly the Hour, wheresoever you cast your Eye; That is to say, that 'tis about 2. of the Clock at Con∣stantinople, 3 at Aleppo, &c. But now, if it be not 12. with you▪ but (v. g.) 3 in the afternoon, when you desire to know the then hour at Constantinople, add the said 3 a Clock to the Figure 2. (which you see lyes, as I now mention'd on the Meridian or Hour-Circle, that runs near that City) and 'twill tell you that 'tis about 5 a Clock there; and thus you must always do, un∣less the time of the Day with you, and the Figure that lies on the Meridian of the place in question make a greater number than 12; for then the Hour sought for, is what remains above 12; as for Example, if it be 11 with you, then this with 2, (i. e. the Figure near the Meridian of Constantinople) making