28 
from the great trilithon to the peak of the Hele stone bore at 
sunrise on the longest day when Stonehenge was building. 
The amplitude of the Sun can be obtained, when his 
declination is known, for any known latitude, by the proportion 
Cosine Latitude Sine Declination 
Sine Radius "Sine of Amplitude 
The Sun’s amplitude, as you know, goes on increasing with the 
latitude until at about latitude 66} it reaches from East to North, 
and then within a circle having a radius of about 23° 30’ from 
the Pole, there is no night, and at the Southern Pole there is no 
day at the season of the Sun’s greatest declination North ; the 
result being reversed at his greatest declination South. And 
now let us, by the equation above mentioned, ascertain what is the 
Sun’s amplitude now at his highest Declination N. in the latitude 
of Stonehenge, namely, 51° 11’. The ground rises from the Hele 
stone to the large trilithon about 4 ft. 6 in. 
Log. cosi. Lat. ay. ... 51° 11'—Rad. = 1-7971501 
Sun’s Declination “ Ba 23°.27' 9" 
+ Aberration of light, less deduc- 
tion for height of horizon, 15 

31’ 22" 
miles distant, 411ft. level of 
Hele stone 382—height of eye 
Log. Sine... fe 2 23° 58’ 31” = 9-6lpeuz2 
Log. Sine Amplitude, A.p. 1897... 40° 24’ 35” = 9°8117421 
And now let us ascertain what the Sun’s amplitude must have 
been if the Hele stone was placed where it is somewhere about 
2,800 years ago. We know that the obliquity of the Ecliptic has 
been decreasing through all historic time. The decrease is at the 
rate of 476 in a century. From our investigations, we know 
