*62

OF THE MENSURATION

he aspired, was not to be obtained. Order andregularity are only to be found in the heavens;and it is to them we are indebted for almost all/ tve know of the earth. We are deceived byevery thing around us ; even our senses misleadus; and what we think ourselves the best ac-quainted with, frequently proves to be anillusion. Objects seen at a distance never appearin their true places ; they are always more or lesselevated, according to the season, and the hourof the day; and on this account, it is not easyto determine either their true height, their di-rection, or the angle at the center, which de-pends upon this direction. By not attending tothese particulars, Riccioli was mistaken near sixthousand toises in the length of a degree.

The next who attempted to find the circum-ference of the earth was Snellius, a German.He measured the distance between Alcmaer andBergen-op-zoom; and by taking the celestial arc,which corresponds to this distance, with properinstruments, he found the length of a degree tobe fifty-five thousand and twenty-one toises.But the person who engaged in this enterprisewith the most success, was our countryman Mr.Richard Norwood. In the year 163 5, he took thefun’s altitude, when it was in the summer solstice,both at London and York, with a sextant offive feet radius, and by that means found thedifference of latitude between these two cities