8 
Aratus,’ by Hipparchus, written in the 2nd century B.c. The 
observations of Eudoxus as handed on by Aratus may have had 
something to do with the discovery of the precession of the 
Equinoxes by Hipparchus. For in that treatise Hipparchus 
mentions that Eudoxus had found that this method for determining 
the Equinoxes was erroneous because the stars shifted their 
position. This, therefore, shows, if my theory is correct, that 
Stonehenge was built before the fallacy was thus exposed, i.e., 
before B.C. 360. 
THE THEORY EXPLAINED. 
For according to my theory the two outlying stones and the 
two mounds were placed where they are, as you see them on the 
map, because it was found that at the instant of sunrise at 
either of the Equinoxes two observers properly stationed within the 
Temple and looking towards them would see certain stars passing 
over them. And at the same time athird observer watching from 
another station would see the sun rise in the East. 
Day after day in Spring time of the year, the rising of the Sun 
and the transits of the stars wculd be looked for, and each of the 
observers would proclaim to the assembled college the event he 
himself observed at the instant it happened, and the same probably 
would be recorded in tablets prepared for the purpose and lying 
on the so-called Altar stone on which the Chief Priest and the 
Registrar we may suppose would be seated. 
And at last the day would come when the glance of the Sun 
and the transits of the stars would be observed to occur 
simultaneously, and then it would be known that the day for the 
celebration of the Equinoctial feast had arrived, and any necessary 
rectification of the Calendar would be made. 
REASONING ON WHICH THE THEORY IS FOUNDED. 
The reasoning and facts on which my theory is founded are as 
follows. Let us suppose a wall of, say, 100 feet long and 20 or 30 
high built at some ascertained angle from the East ; then if looking 
