C 66 ] 
fest from inspection, must be south 30 degrees east. 
Remember always to draw the courses towards 
you. 
If a traverse be so large as to require to be pro¬ 
tracted on more than one sheet, draw north and 
south and east and west lines as 1 d. b 7. a 1. c d 
^ through the extreme points of the protraction on 
each of the sheets, before taking them off the 
board, as guides by which to join them properly to 
each other. 
The instrument may be made more complete by 
filling up the spaces at 1. K. L. M. so as to make 
them useful 'receptacles for dividers, pencils See. 
To do which fasten the rims oo. oo. oo. oo. to the 
frame so as not to press on the moveable circular 
board, and make a thin bottom to the spaces be¬ 
tween them and the corners of the frame. 
In the right hand part of the frame a recess may 
be sunk to lay a scale in, when wanted for use, so 
as that it shall not impede the sliding of the square 
over the instrument. 
I HAVE found this instrument to facilitate and 
expedite protracting more than any other that has 
hitherto been brought into use. In lengthy traver¬ 
ses of roads and waters its service has been found 
to be very great. In such protractions as much can 
be done in one day with it as can be done in four at 
