Very few placenames appear but both show numerous physical features. Below each sphere are two smaller spheres and another diagram, all showing mathematical or astronomical calculations. All items are subject to prior sale. Prior customers, libraries and institutions can be billed.
Prior payment is required from new customers.
All items are subject to prior sale. Prior customers, libraries and institutions can be billed. Prior payment is required from new customers. All items are subject to prior sale. Prior customers, libraries and institutions can be billed.