THE ARTS AND INDUSTRIES 



practical application of the lever, and is used to enlarge 

 drawings or to make them smaller. It is made from four 

 long, thin sticks which have holes, at regular intervals, 

 in which pegs may be inserted. The block on the right 

 hand lower corner is fixed to the table. All the rest of 

 the pantagraph is free to move. The point under 

 the hand does not mark; the point over the smaller pic- 

 ture is a pencil. The little wheel at the left of the 

 pantagraph is not necessary but allows it to move more 

 freely. By moving the point over all the lines in a 

 drawing an exact copy is made by the pencil only the 

 new drawing is smaller in this case. To enlarge a draw- 

 ing the non-marking point is placed where the smaller 

 picture is, and the pencil is placed where the hand in the 

 picture now is. 



When studying the lever you learned that the small 

 force moves a longer distance than the large force. The 

 pantagraph may be considered as four levers all acting 

 together. A certain motion of one part will make a 

 larger or smaller motion of another part according as 

 the lengths of the arm are changed by changing the pegs. 

 Make a pantagraph and copy some drawings. 



81. Levelling. 



It is very often desirable to know how to make level 

 the foundations of a building. The illustration shows a 

 very simple method which has been used for many years. 

 The apparatus is made of the size as shown. The plumb- 

 bob hangs from (b), and the plumb-line is kept from 

 swinging too much by some wide staples. To adjust 

 the apparatus rest the two ends upon two stakes driven 



