# Make your Own Dial – Part I - PowerPoint PPT Presentation

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Make your Own Dial – Part I. D. 1. Draw two perpendicular lines AB, and CD. Where they intersect is O, the origin 2. Draw CB’ from C, using your latitude as the angle between CB’ and CD. 3. Draw a line from the origin O, (where AB and CD

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Make your Own Dial – Part I

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### Make your Own Dial – Part I

D

1. Draw two perpendicular lines AB, and CD.

Where they intersect is O, the origin

2. Draw CB’ from C, using your latitude as the

angle between CB’ and CD.

3. Draw a line from the origin O, (where AB and CD

cross) perpendicular to CB’. Call this line OP

O

B’

A

B

P

LAT

C

D

4. Draw an arc of length OP with a compass

5. Where the arc passes through the line OD,

mark the point N

6. Using the compass with the same length OP,

and draw a circle around point N. It should

just touch the line AB at the origin point O

N

O

B’

A

B

P

LAT

C

### Make your Own Dial – Part III

D

7. Starting from O, mark every 15 degrees

around the edge of the circle

8. Draw lines from N through these circle points

until they meet line AB. These are the hour

hour points.

N

O

A

B

C

D

9. Connect point C with each of the hour lines,

meeting them across line AB

10. Label the lines from C, starting with line CD

as 12 pm. The lines will span the time from

7 am to 5 pm

11. To finish, draw a line parallel to AB through

point C and label the ends as 6 am (left) and

6 pm (right)

N

O

A

B

7

8

9

10

11

12

1

2

3

4

5

6

6

C

N

W

E

8

9

10

11

12

1

2

3

4

S

5

7

6

6

C

### Make your Own Dial – Part V

12. Draw a triangle gnomon. The acute angle

is equal to the latitude.

13. The high side of the triangle may be

artistically curved to a pleasing shape

14. The gnomon goes onto the dial face on

the C to 12 line, with the gnomon’s acute

point placed at C. The dial C to 12 line

is pointed north. Then the hypotenuse of

the gnomon will be parallel to the earth’s

axis of rotation.

GNOMON

LATITUDE

C

12