“In my early days I frequently visited Stonehenge to make observations at sunrise as well as by starlight.  I noticed that the lower edge of the impost of the outer circle forms a level horizontal line in the heavens, equi-distant from the earth, to the person standing near the centre of the building, about 15 degrees above the horizon on all sides.

“Stonehenge stands on rather sloping ground; the uprights of the outer circle are nearly a foot taller on the lower ground or western side than they are on the eastern, purposely to keep the horizontal level of the impost, which marks great design and skill.  The thirty uprights of the outer circle are not found exactly of equal distances, but the imposts (so correctly true on their under bed) are each of them about 7 cubits in length, making 210 cubits the whole circle.

“If a person stands before the highest leaning-stone, between it and the altar stone looking eastward, he will see the pyramidal stone called the Friar’s Heel, coinciding with the top of Durrington Hill, marking nearly the place where the sun rises on the longest day.  This was the observation of a Mr. Warltire, who delivered lectures on Stonehenge at Salisbury (1777), and who had drawn a meridian line on one of the stones.  Mr. Warltire asserted that the stone of the trilithons and of the outer circle are the stone of the country, and that he had found the place from whence they were taken, about fourteen miles from the spot northward, somewhere near Urchfont.

“If the person so standing turns to his left hand, he will find a groove in one of the 6-foot pillars from top to bottom, which (in the lapse of so many ages, and swelled by the alternate heat and moisture of two thousand years, has lost its shape) might have contained in it a scale of degrees for measuring; and the stone called the altar[3] would have answered to draw those diagrams on, and this scale of degrees was well placed for use in such a case, for one turning himself to the left, and his right hand holding a compass, could apply it most conveniently.  With all this apparatus the motions of the heavenly bodies might have been accurately marked and eclipses calculated, a knowledge of which, Caesar says, they possessed in his time.

“Wood and Dr. Stukeley both make the inner oval to consist of nineteen stones, answering to the ancient Metonic Cycle of nineteen years, at the end of which the sun and the moon are in the same relative situation as at the beginning, when indeed the same almanack will do again.

“In my younger days I have visited Stonehenge by starlight, and found, on applying my sight from the top of the 6-foot pillars of the inner oval and looking at the high trilithons, I could mark the places of the planets and the stars in the heavens, so as to measure distances by the corners and angles of them....

  “It is very remarkable that no barrow or tumulus exists on the east
  side, where the sun (the great object of ancient worship) first
  appears.”