GLOBES. 33 



FRAMED MAPS. 



The various kinds of gum-elastic maps may be framed with 

 the same material, and inflated with the self-acting valve tube, 

 as represented in plate , fig. . When gilded or bronzed, 

 these aerial frames resemble very closely the wooden gilded 

 article ; and when collapsed, they occupy very little space. 

 Maps framed in this way may also be used as bathing mats and. 

 carpets for children, without injury to the engraving or coloring, 

 while the increased expense of the map on account of the frame 

 is very trifling. 



CHARTS. 



Are made of vegetable leather, or what might for this use be 

 properly termed gum-elastic parchment. The same general re- 

 marks that have been made in regard to maps, will apply to 

 charts. They also possess another superior quality, which is 

 particularly requisite for charts. The dimensions of this parch- 

 ment do not vary like paper when damped for printing ; in 

 like manner the dimensions of these charts do not vary from 

 change of atmosphere. They may be exposed to wet, and to 

 salt water for any length of time with impunity. The vessel's 

 course can also be marked on them with pencil or ink, and 

 afterwards washed off", if desired. 



GLOBES. 



The globe has heretofore been so expensive as to be found in 

 schools only of the higher class. No form of map or atlas can 



