The four angles being thus ascertained, and two sides of the quadrilateral being radii of the earth; the two remaining sides and the diagonal, or in other words, the moon's distance from the two places of observation and from the centre of the earth, could be ascertained, at least in terms of the earth's radius, from elementary theorems of geometry.
"A System Of Logic, Ratiocinative And Inductive (Vol. 1 of 2)"
John Stuart Mill
The town was, as we have seen, enclosed by walls, perhaps by Canute, certainly by the Normans, and these seem to have been enlarged by King John, and rebuilt and repaired after the French raid of 1338. They formed a rude quadrilateral, roughly seven hundred yards from north to south, and three hundred from east to west, were from twenty-five to thirty feet high and of varying thickness.
"England of My Heart--Spring"
Edward Hutton
In any case, the Roman walls, built we may think in the fourth century, enclosed an irregular quadrilateral, and possessed four gates out of which issued those four roads to Old Sarum, to Silchester, to Clausentum and to Porchester.
"England of My Heart--Spring"
Edward Hutton