1893.] Orientation of a number of G-reek Temples, 8fC. 381 



Olympia, lat. 37° 38' N. 



Temple 



of 

 Jupiter. 



Orientation 

 angle. 



Amplitude, star or sun 

 Corresponding altitude 



Stellar 

 elements. 



Solar 

 elements. 



Name 

 of 



star. 



\ ' 



i ;• - - ■■: 



262 37 46 



8 38 ON. 

 3 OE. 

 + 8 40 



6 h n m 37s 



23 h 40 m s 

 B.C. 740 



7 22 14 N. 

 1 42 OE. 

 + 6 52 22 

 7 h 34 m 52 s 

 14° 12' 0" 

 l h 3 m 5 s 

 Apr. 6. 







Depression of sun. . . 



Right ascension 



Approximate date . . 



This example has been selected from the rest of the list, because 

 this temple has been chosen for the purpose of showing the method 

 of procedure in working out the elements from the observations, 

 those, namely, of the orientation angle, and of the height of the 

 visible horizon. 



A few general remarks, however, seem required respecting the 

 Sun's and star's altitude, and the Sun's depression when the star 

 is to be observed. 



For a star to be seen heliacally. it is necessary that the Sun sbould 

 be just sufficiently below the horizon for the star to be recognised. 

 According to Biot, Ptolemy, speaking of Egypt, has recorded this to 

 be about 11°. But where, as generally in Greece, there are moun- 

 tains screening the glow which at such times skirts the true horizon, 

 it seems fair at any rate for a first magnitude star to consider 10° 

 as sufficient. I have myself seen Rigel in the same direction as the 

 Sun when elevated 2° 40' above the sea horizon, the Sun being less 

 than 10° below. Obviously an observer looking from a dark chamber 

 in a well known direction would be more favourably situated. 



It is proper to allow about 3° of altitude for a star to be seen above 

 low clouds and the hazy glow which skirts the horizon. The Sun's 

 light, however, seems to be very effective at a lower altitude, and when 

 he appears over a mountain of 2° or 3° altitude the angle may 

 properly be reduced by 20' or 25', partly for refraction, and partly 

 because a small segment only of the disk is sufficient for illumina- 

 tion. 



The method I have pursued in working out the example of the 

 Temple of Jupiter at Olympia is as follows. 



The orientation angle, measured from the south point round by 

 way of west and north, is 262° 37' 46", which is equivalent to an 

 amplitude of +7° 22' 14". The eastern mountain subtends an 

 angle of 2° 4'. For reasons above given, the solar altitude may be 



