Xll 



DESCRIPTION AND USE OF THE SIDEREAL MAPS. 



the graduated meridian line at 41, is the circle of perpetual apparition, the stars within that circle being 

 visible at all times from the meridian of Greenwich. 



The maps may, by a little calculation, be made to represent the aspect of the heavens at other times 

 than is named ; for instance, reckoning backwards, and allowing a difference of about twenty minutes for 

 every five days, or four minutes for every twenty-four hours, we find that on the 21st of January at 40 

 minutes past 1 o'clock in the morning, the stars will appear as they are represented in the map for March, 

 and so on for every other month, following the same reckoning for every day in the year. 



TABLE SHOWING THE HOUK AND DAY WHEN THE STABS OCCUPY THE 

 POSITION INDICATED IN THE MAP. 



January 21 

 26 



February 1 



6 



11 



16 



April 

 May 



22 



27 



2 



7 



12 

 17 

 22 



26 



31 



5 



10 

 15 

 20 

 25 



November 3 

 8 

 13 

 18 

 23 

 28 



July 

 August 



hr. 

 2 

 1 



1 



12 

 12 

 12 



hr. 

 1 

 1 

 1 



12 

 12 

 12 

 11 



hr. 

 1 



12 

 12 

 12 

 11 



Map for March. 



February 21 



26 

 3 



8 

 13 



18 



March 



hr. 



- 11 

 -, 11 



- 11 



- 10 



- 10 



- 10 



Map for June. 



May 

 June 



27 



1 



6 



11 



1C 



21 



hr. 



- 11 



- 11 



- 11 



- 10 



- 10 



- 10 



Map for September. 



hr. 



August 30 - - 11 



September 4 - - 11 



9 



14 

 19 

 24 

 29 



- 10 



- 10 



- 10 



- 9 



- 9 



December 3 

 8 



13 

 18 

 23 



Map for December. 



hr. 

 - 11 



- 11 



- 10 



- 10 



- 10 



- 9 



40 

 20 





 40 

 20 







March 

 April 



June 

 July 



October 



January 



23 



28 



2 



7 



12 

 17 



26 



1 



6 



11 



16 



21 



4 

 9 

 14 

 19 

 24 

 29 



3 

 8 

 13 

 18 

 23 

 28 



hr. 

 9 

 9 

 9 



7 



7 

 7 



hr. 



9 

 9 

 9 

 8 

 8 



8 



hr. 

 9 



8 

 8 



8 

 7 



7 



hr. 

 9 

 9 

 8 

 8 

 8 

 7 



m. 

 40 

 20 





 40 

 20 







m. 

 40 

 20 





 40 

 20 









 20 

 20 





 40 

 20 



m. 

 20 





 40 

 20 





 40 



Temple of the winds, Athens 



