BENJ. PIKE S, JR., DESCRIPTIVE CATALOGUE. 

 Fig. 76. 



The Pantagraph. (Fig. 76, as above.) The pantagrapli 

 is usually made of ebony or brass, from 12 to 24 inches long, 

 and consists of four flat rules, two of them long and two of 

 them short. The two longer are joined at the end by a 

 double pivot, which is fixed to one of the rules, and works in 

 two small holes placed at the end of the other. Under the 

 joint is an ivory castor, to support this end of the instrument. 

 The two smaller rules are fixed by pivots near the middle of 

 the larger rules, and are also joined together at their other 

 end ; by the construction of this instrument, the four rules 

 always form a parallelogram. There is a sliding box on the 

 longer arm, and another on the shorter arm. These boxes 

 may be fixed at any part of the rules, by means of their 

 milled head screws ; each of these boxes is furnished with 

 a cylindrical tube, to carry either the tracing point, crayon, 

 or fulcrum. The fulcrum or support, B, Fig. 76, is a leaden 

 weight ; on this the whole instrument moves when in use, 

 there being movable rollers under different parts of the in- 

 strument to facilitate the movement thereof. The gradua- 

 tions are placed on two of the rules, B and D, with the pro- 

 portions of ^, ^-, ^, &c., to yV, marked on them. The pencil 



