24 BENJ. PIKE'S, JR., DESCRIPTIVE CATALOGUE. 



is divided into three equal parts ; and thus you proceed for 

 any number of parts under 10 or 12. There are also some- 

 times placed on the face, a scale of plans, solids, and circles. 

 They are sometimes made with an adjusting screw, or a 

 tooth and pinion to move the slide, and which admits of 

 great nicety in the adjustment of the index. 



Price, in brass, $4.50 ; with rack and ) ~ fi 



pinion motion, j" 



" German silver, $7.00 ; " " $8.50. 



" with adjusting points, $2.00 extra. 



Bisecting Compasses, or whole and halves. (Fig. 26, 

 page 25.) A name given to these compasses, because, 

 when the longer legs are opened to any given line, the 

 shorter ones will be opened to the half of that line ; being 

 always a bisection. 



Price, in brass, $2.00 to $3.00. 



" in German silver, $3.00. 



Triangular Compasses. (Fig. 27, page 25.) They con- 

 sist of a pair of compasses, to whose head a joint and 

 socket is fitted for the reception of a third leg, which may 

 be moved in almost every direction. These compasses, 

 though exceedingly useful, are but little known ; they are 

 very serviceable in copying all kinds of drawings, as from 

 two fixed points they will always ascertain the exact posi- 

 tion of a third point. 



Price, in German silver, $5.00 and $7.00. 



The Pillar Compasses. (Fig. 28, page 27.) A universal 

 instrument, and is, when opened, about six inches long; 

 the points are made to turn up so as to occupy but about 

 half that space ; within the two legs are contained the ink 

 and pencil points, held firmly by a spring joint ; either of 

 these can be taken out and the plain points inserted in their 

 places. Thus, by shifting them around, making a pair of 

 compasses with plain point, ink point, and pencil point. 

 Also, the points can be used taken out of the legs of the 

 instrument as bow pen, and bow pencil, there beino- a 

 small head attached to each for that purpose. This instru- 

 ment forms in itself a pocket case of instruments. 



Price, in brass, $4.00 to $6.50. 



" in German silver, $5.00 to $10.00. 



