6. On your nocturnal, draw lines from your marks showing the position of the pointer stars to the center of the nocturnal (you may need to take the straw out to make this easier). You should have two angles, one from mark 1 to mark 2 and one from mark 2 to mark 3. Measure these angles. From the times each mark was made, figure out how many minutes elapsed from mark 1 to 2, and from mark 2 to 3.

7. From your data in #6, divide degrees by minutes for mark 1 to 2 and also from mark 2 to 3. Find the average of these two numbers (degrees/min). Since there are 60 min/hour, multiply this average by 60 to get degrees/hour.

8. From #7, how many degrees around the North Star would the Big Dipper move in 24 h? 9. Set the tab on the time dial to the correct date on the nocturnal base. Use your marks (you know the times for these from a clock)and your answer to #7 to make markings for hours on the time dial of your nocturnal.

10. If the nocturnal reads 9:00 for November 1st, what time would it be if the Big Dipper were in the same position on February 1st?