MECHANICAL DRAWING SUPPLIES 227 



lead has been placed. This second slat is coated with glue 

 before being fitted over the lead, so that the two slats hold 

 fast after being brought together. After the glue has se', 

 thoroughly, the slats are fed lengthwise into another machine 

 which separates their six parts into six pencils. 



Since there is a demand for pencils of every grade, from the 

 soft pencil of the news editor to the hard pencil of the drafts- 

 man, pencils are made in sixteen grades of hardness. These 

 grades vary widely enough to meet every demand. 



272. Drawing Paper. Paper is a fabric or kind of cloth 

 composed of numerous fibers or threadlike filaments, the 

 rough edges of which cause them to stick together. Draw- 

 ing paper and other fine grades of paper are made from linen 

 rags. The first step in the process of manufacture is to 

 place the rags in a vat filled with water and to beat and 

 tear them until they are transformed into paper pulp, a 

 substance which looks very much like cottage cheese. The 

 pulp is then taken to another vat where it is mixed and 

 churned with more water until in its more diluted form it 

 becomes of the thickness or consistency of cream. This 

 creamlike substance is then allowed to flow over the screen 

 of the paper machine on which ifc is transformed imo long 

 rolls or sheets of paper. 



The paper machine consists of a fine screen of wire about 

 6 ft. wide and 200 or more feet long. The screen runs over 

 rollers on the principle of an endless belt. The creamlike 

 pulp is allowed to flow on one end of the traveling screen 

 which vibrates as it moves along. The water in the pulp 

 gradually drains through the screen on which the fibers settle 

 evenly in the form of a porous sheet, like ve:y spongy blot- 

 ting paper. As the screen travels along it passes between 



