CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This is a continuation of co-pending U.S. patent application Ser. No. 11/332,598, filed Jan. 9, 2006, priority of which is claimed and which is incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable  
       REFERENCE TO A “MICROFICHE APPENDIX” 
       [0003]     Not applicable  
       BACKGROUND  
       [0004]     The present invention generally relates to rulers and compasses.  
       SUMMARY  
       [0005]     In one embodiment is disclosed a ruler for drawing or measurement of circles, straight lines, and angles. The ruler body has a longitudinal slot in the middle and parallel with the length of the ruler. A sliding pen or pencil holder is placed within the slot for drawing or measuring. A compass is included in the combinations.  
         [0006]     In one embodiment is disclosed a compass ruler wherein it is easy to compare SAE or English units with Metric units for measuring, sketching, or using the ruler as a compass for drawing a circle.  
         [0007]     In one embodiment all lines to be sketched, radii of circles, or other objects may be measured in both SAE and Metric units at the middle of the ruler.  
         [0008]     In embodiment is compared the different units of SAE and Metric before drawing.  
         [0009]     In one embodiment is disclosed the combination of a straight ruler, protractor, and compass, which can be used as a simple ruler for sketching or drawing a line using a track in the middle of the ruler and parallel to the ruler&#39;s length.  
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0010]     For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:  
         [0011]      FIG. 1  is an overall top view of one embodiment.  
         [0012]      FIG. 2  is a top view of the body of the ruler shown in  FIG. 1 .  
         [0013]      FIG. 3  is a side view of the body shown in  FIG. 2 .  
         [0014]      FIG. 4  is a top view of a holder.  
         [0015]      FIG. 5  is a top view of a nut.  
         [0016]      FIG. 6  is a top view of a screw.  
         [0017]      FIG. 7A  is a top view of the upper section ruler of  FIG. 1  showing various measuring scales.  
         [0018]      FIG. 7B  is a top view of the lower section ruler of  FIG. 1  showing various measuring scales. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]     The professional compass-ruler  10  combines the advantages of a compass, protractor, and ruler. It can be used for finding, drawing, or measuring an angle, circle, or straight line at the center of the ruler&#39;s length.  
         [0020]      FIG. 1  is an overall top view of one embodiment of compass-ruler  10 .  FIG. 2  is a top view of the body  20 .  FIG. 3  is a side view of the body  20 .  FIG. 4  is a top view of a holder  100 .  FIG. 5  is a top view of a nut  80 .  FIG. 6  is a top view of a screw  90 .  FIG. 7A  is a top view of the upper section compass-ruler  10  showing various measuring scales.  FIG. 7B  is a top view of the lower section ruler of compass-ruler  10  showing various measuring scales.  
         [0021]     In one embodiment compass-ruler  10  comprises body  20  with upper  30  and lower  40  sections, track or slot  50 , and pen or pencil holder  100  slidably connected to track or slot  50 . Track or slot  50  can have centerline  56 , along with first 200 and second 300 liner measuring scales. First measuring scale  200  can have inner  210  and outer  220  indicia. Second measuring scale  300  can have inner  310  and outer  320  indicia. Upper section  30  can be fixed to lower section  40 . Upper section  300  can include angular measuring scale  400  and larger angular measuring scale  410 .  
         [0022]     When drawing lines a pen  5  (not shown) travels along and through the ruler&#39;s  10  track  50  to leave a mark (e.g., on drawing paper). The ruler&#39;s  10  track  50  is straight from O dimension  60  to the end  70  of the ruler&#39;s  10  length.  
         [0023]     For finding or drawing an angle—start from the central line  56  of the ruler&#39;s  10  track  50  at 180 or O (at upper opening  60 ) and then read the number of an angle on scale  400 . If the angle is larger than 180 on the left of a central line, the degree appears on the retractor scale  410 , and is the same of the degree at the opposite straight to another side below of an axis; add these numbers for the degree of an angle.  
         [0024]     The professional compass-ruler  10  may also be used as a compass for drawing circles which have a radius within the length the ruler&#39;s  10  track  50  (between 1/16th of an inch to 12 inches as shown in  FIG. 7A and 7B ). For drawing a circle; the compass-ruler  10  can be held down by spindle screw  90  with nut  80  at upper opening  60 —this point is center of the circle to be drawing. The pen or pencil holder  100  can be slid down track  50  to the selected radius of the circle to be drawn, and ruler  10  swung or rotated to make a circle.  
         [0025]     The material for reproduction of the professional compass-ruler can include cleared mica, thin wood or stainless steel; and the ruler&#39;s  10  track  50  can be magnetic to easily slide or clutch holder  100  on tight when drawing.  
         [0026]     The following is a list of reference numerals.  
                                                   LIST OF REFERENCE NUMERALS            Part Number   Description                    5   pen or pencil       10   compass ruler       20   body       30   upper section of body       40   lower section of body       50   track or slot       52   upper end of track or slot       54   lower end of track or slot       56   center line of track or slot       60   upper opening for nut and screw       70   lower opening for nut and screw       80   nut       90   screw       100   pen or pencil holder       110   opening in holder       200   first linear measuring scale       210   inner indicia       220   outer indicia       300   second linear measuring scale       310   inner indicia       320   outer indicia       400   angular measuring scale       410   larger angular measuring scale                  
 
         [0027]     All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise.  
         [0028]     The foregoing embodiments are presented byway of example only; the scope of the present invention is to be limited only by the following claims.
A ruler for drawing or measurement of circles, straight lines, and angles. The ruler body has a longitudinal slot in the middle and parallel with the length of the ruler. A sliding pen or pencil holder is placed within the slot for drawing or measuring. A compass is included in the combinations.