344 IMPLEMENTS FOR DRAWING. 



The best kind of drawing-boards, however, are 

 made with a frame and a moveable pannel, upon 

 which the paper is simply put wet, and then 

 forced into the frame, where it is confined by 

 wedges at the back. This strains equally well 

 without the trouble of pasting, so that you may 

 dry it at the fire ; and it also looks much neater. 

 These drawing-boards may be bought at most 

 colour-shops. It is necessary to mention, that all 

 the angles of drawing-boards should be exactly 

 square. 



Parallel rulers are for drawing parallel lines 

 readily : they are made of two pieces of ebony fas- 

 tened together by brass bars, so as always to move 

 parallel to each other. They may be bought of 

 different kinds and prices, at the mathematical 

 instrument makers. 



Tee-squares are rulers made in the form of the 

 letter T, which are used with the drawing-boards ; 

 the short end, called the stock, being apphed to 

 the edge of the board, so as to slide forwards and 

 backwards ; while the long part, called the blade, 

 is used for drawing lines by. These are more con- 

 venient than parallel rulers, wlien a drawing-board 

 is used, as by them you draw lines at right 

 angles to each other at once, without using the 

 compasses. 



Dividing compasses are instruments of brass and 

 steel, for dividing lines, and laying down measures 

 from scales, &c. : they are generally sold in cases, 

 containing also a steel pen for drawing lines cleaner 

 than can be done by a common pen, which is very 

 useful where neatness is required ; and points with 

 a black lead pencil, for putting into the compasses, 

 when circles are to be described. These cases 

 also contain scales of equal parts, and protractors 



