INCOMPRESSIBLE GLOBES. 35 



SECTIONAL GLOBES. 



Sectional globes, as represented in the diagrams, Plate , 

 figs. are made from caoutchouc boards or whalebone, which 



is coated with India rubber tissue. or elastic compound. The 

 sections are fitted into the edges of the polar circles or discs, 

 which are formed with grooves to secure them in their several 

 places. When the sections are matched together, before they 

 are fitted to both the polar discs, they are fastened together at 

 the equator by a caoutchouc whalebone hoop, wdiich is sHpped 

 into catches upon the sections on the inside, and also by an axis 

 passing through the globe and fastened at the poles. This method 

 of manufacturing globes from gum-elastic is the invention of 

 another.* They may be easily taken apart, and combine the 

 firmness of the ordinary pasteboard or plaster globes with the 

 compactness and portability of the flexible ones which are made 

 of India rubber. 



INCOMPRESSIBLE GLOBES. 



The only question which has been raised as to the utility of 

 caoutchouc compressible or inflated globes is, whether they can 

 be made firm and exact enough to be mounted for working 

 problems with as much precision as the common plaster globe. 



If this be granted, the objection may be removed by making 

 the shells and horizon of caoutchouc whalebone covered with 

 printed India rubber tissue, instead of paper, and the frame of 

 caoutchouc-ivory. Globes made in this manner will be lighter, 

 stronger, and as exact for the working of problems as the 

 plaster globe. 



* Charles Goodyear, Jr. 



