He was the first who established a distinction of climate by the length of days and nights:  and he is said to have discovered the dependence of the tides upon the position of the moon, affirming that the flood-tide depended on the increase of the moon, and the ebb on its decrease.  By means of a gnomon he observed, at the summer solstice at Marseilles, that the length of the shadow was to the height of the gnomon as 120 to 41-1/5; or, in other words, that the obliquity of the ecliptic was 23:50.  He relates, that in the country which he reached in his voyage to the north, the sun, at the time of the summer solstice, touched the northern part of the horizon:  he pointed out three stars near the pole, with which the north star formed a square; and within this square, he fixed the true place of the pole.  According to Strabo, he considered the island of Thule as the most western part of the then known world, and reckoned his longitude from thence.

With respect to the extent and discoveries of his voyage to the north, there is great difference of opinion.  The veracity of Pytheas is utterly denied by Strabo and Polybius, and is strongly suspected by Dr. Vincent:  on the other hand, it has found able supporters in D’Anville, Huet, Gessner, Murray of Goettingen, Gosselin, and Malte Brun; and in our opinion, though it may not be easy to ascertain what was really the country which be reached in his voyage, and though some of the particulars he mentions may be fabulous, or irreconcileable with one another, yet it seems carrying scepticism too far to reject, on these accounts, his voyage as altogether a fiction.

The account is, that Pytheas departed from Marseilles, coasted Spain, France, and the east or north-east side of Britain, as far as its northern extremity.  Taking his departure from this, he continued his voyage, as he says, to the north, or perhaps to the north-east; and after six days’ navigation, he arrived at a land called Thule, which he states to be 46,300 stadia from the equator.  So far there is nothing improbable or inconsistent; but when he adds, that being there at the summer solstice, he saw the sun touching the northern point of the horizon, and at the same time asserts that the day and night were each of six months’ continuance, there is a palpable contradiction:  and when he adds, that millet was cultivated in the north of this country, and wheat in the south, and that honey abounded, he mentions productions utterly incompatible with his description of the climate and latitude.

As, however, this voyage forms an important epoch in the history of discovery, it may be proper to endeavour to ascertain what country the Thule of Pytheas really was.  We have already observed, that the day’s sail of an ancient vessel was 500 stadia, or 50 miles; supposing the largest stadia of 666-2/3 equal to one degree of the equator, if the vessel sailed during the night as well as day, the course run was, on an average, 1000 stadia, or 100 miles.  Now, as the