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First the globe is chosen. The globe is actually a round bottom chemical flask made in Europe. The globe is hand picked from the inventory of the distributor. Globes with blemishes are rejected. Once the globe has been chosen the neck is removed with a diamond saw. At this point the globe is mounted in a drill press, filled with water for stability, and a circular hole is drilled in the globe again using a diamond drill. This hole will eventually be used to install the central pointer. The globe is then mounted on the laser jig, ready for scribing. The scribing information is then calculated. The latitude and longitude, the local time zone, the use or not of daylight savings time, the use or not of a 12 hour clock, all determine the information that is placed on the globe. This information is fed into a computer program (written in Runtime Revolution on a Macintosh) and using the CIA developed database of the shorelines of the world, the positions of approximately 140,000 dots are determined. This information is fed to another computer that in turn feeds commands to two servo motors that control the position of the globe with respect to the laser. See scribing details for more details of the laser jig and the scribing process. Once the scribing is complete, the base is made. The base is composed of three wooden pieces and a silicon gasket/grommet. The base that supports the globe, the central pointer and the split ring that covers the grommet are made of hard wood. Usually Honduras mahogany or walnut. The split ring is made in two parts so that the ring may be placed inside the globe. Once inside the two halves are joined. The gasket/grommet is cast from Silicon RV, a material that sets up in about 24 hours. The gasket/grommet allows the base and pointer to be aligned and to keep the inner pointer and ring from touching the globe. An O ring in the base keeps the globe from touching the base. This configuration means that the glass globe is cushioned between soft components. |
