IMPLEMENTS FOR DRAWING. 34,5 



for laying down angles. . All these may be had at 

 the instrument makers. 



Black lead pencils are made of plumbago sawed 

 into slips, and fitted into sticks of cedar. They are 

 of various qualities. The best are fine, without any 

 grit, not too soft, and that cut easily without break- 

 ing. An inferior kind is made by mixing up the 

 dust of plumbago with gum or glue, and thus form- 

 ing a composition, which is fitted into sticks in the 

 same manner as the best : these are always gritty, 

 and do not answer so well for most drawings ; yet, 

 being cheaper, they may be used upon many occa- 

 sions. It is necessary to examine pencils before 

 any quantity is bought, by cutting one of them, 

 because the composition pencils, having the same 

 outward appearance, are often sold for the best. 



Indian rubber > or elastic gum, as it is also called, 

 is a substance much like leather, which has the 

 curious and useful property of erasing or defacing 

 lines drawn with black lead ; it is, therefore, much 

 used for this purpose. It is brought chiefly from 

 South America, in the form of small bottles, which 

 are cut up into slips. It is originally the juice of 

 a tree that grows very abundantly in Surinam, and 

 is like milk when exuded from the tree, but soon 

 becomes solid when exposed to the air. The na- 

 tives form balls of clay, which they smear over 

 with this milk : when this coating is almost dry, 

 they apply another, and so on, till it is of the re- 

 quired thickness ; they then moisten the clay with 

 water, which does not dissolve the Indian rubber, 

 and wash it out. These bottles are used by the 

 natives for containing water, or other liquors. It 

 is a production common to the East Indies also, 

 from whence it is imported in various forms, 



