The English globe being a stabil and immobil one, performing what the ordinary globes do, and much more / invented and described by the Right Honorable, the Earl of Castlemaine ; and now publish't by Joseph Moxon ...

Operation I. To set the Globe level or parallel to the Horizon.

I Begin here, because 'tis what we first suppose done in most Operations, especially in the nice ones, nor is the perform∣ance difficult, for we have nothing to do, but to place the String and Plumet exactly upon the South side of the Meridian or 12 a Clock hour Circle, and if it hangs just over the little Star on the Pedestal, then the Plane where the Globe stands is Horizontal and Level; otherwise 'tis faulty as much as the Plummet varies from being Perpendicular to the said Star; for the Star (you must suppose) is engraved by the Globe-maker there, where he found the Plumet to hang upon his Placing the Globe truly level.

Let therefore the String and Plumet be always long enough to touch almost the Pedestal, for thereby you may better per∣ceive any Error; and remember also that in case the said Pe∣destal (to be less cumbersom) be not as big as the Diameter of the Globe, then there is to be under it a little wooden Ruler, which being drawn out, and markt with a Star will serve for this and several other uses as you will see anon.

There is another way speculatively true, tho perchance not so exact in practice, which is thus perform'd. Place your Globe on your Plane with the String lying on the Meridian as before, and if the Extuberancy or swelling of the Globe just touches and bears up the String at the Horizontal Circle, then

the Plane is Level, or Parallel to the Horizon, otherwise it differs as many degrees, as are between the point, where the said String touches the Globe, and its Horizon.

The reason of this is, That seeing the greatest and most extu∣berant Circle on a Globe is that which lies 90 degrees from its Pole, the Horizon becomes here the greatest and most extube∣rant one that can be described from the Zenith, therefore the Globe being on a Level which makes its Zenith to correspond with the Zenith in the Heavens, the String cannot fall short of the Horizon, because it must rest on the most extuberant Circle that occurs; nor can it touch below it, because the Plum∣met drawing the said String perpendicular from the greatest extuberancy, hinders its bending, and consequently its inclina∣tion to any part of the Globe beneath the Horizon. Now if the Plane be not level, then the Zenith of the Globe and Hea∣vens not corresponding, another Circle or part of the Globe, in∣stead of the Horizon must have the greatest extuberancy and this Circle, being 90 Degrees from the point of the Globe, (which lies directly under our Zenith) it must differ from the Horizon of the Globe, as many Degrees as its Zenith differs from that in the Heavens; therefore the way prescribed is at least speculatively true.

Notes

• The first way.
• A Memoran∣dum.
• The second way.
• The Reason and Demon∣stration of the Operation.