SLATE AND PEN-WIPER. 37 



SELF-INFLATING GLOBES. 



All the different kinds of flexible globes described, may be 

 made self-inflating by suspending them from the top or north 

 pole, when they are hooped on the inside. This is done by a 

 series of hoops, which may be made of wood, metal, or caout- 

 chouc whalebone, according to the size of the globe, and the 

 materials of which they are made, the hoops lessening in cir- 

 cumference from the equator north and south, as they approach 

 the poles, each globe requiring about seven of these hoops ; they 

 are covered with tissue, and cemented to the globe on the inside 

 during the process of manufacture. When packed, the hoops 

 fit one within the other, causing the globe to occupy but a very 

 small space. Although they cannot be packed in so small a 

 space as those that are not hooped, they are in other respects 

 much the most convenient ; and the whalebone hoops may also 

 be bent or doubled crosswise, and they will again resume their 

 shape, see fig. . These, as well as all the globes before de- 

 scribed, may be mounted like other globes by the insertion of an 

 axle, or pivot, in the tubes at the poles, one of which, the self- 

 acting valve tube, is designed for inflating the globe, the other 

 for letting off" the air. 



BLACK AND WHITEBOARD. 



SLATE AND MEMORANDUM PAPER. 



Experiments have recently been made with the gritted goods 

 for these purposes, which promise to be successful. A par- 

 ticular account of them will be deferred until more is known of 

 their utility. 



SLATE AND PEN-WIPER. 



This trifling article is made of gum-elastic sponge, and is very 

 complete for the use for which it is designed. 



