496; and thus the world had
been nearly rounded before what would now be regarded as the ordinary
knowledge of a navigator had been acquired. England has the honour of
making the first advances. It was an Englishman, Norwood, who made the
first measurement of a degree between London and York, and fixed it at
122,399 English yards. The attention of the world thus once awakened,
Huygens and Cassini applied themselves to ascertain the figure of the
earth. The first experiments of the French _savans_ were in
contradiction to Newton's theory of the flattening of the poles; but
the controversy was the means of exciting new interest. The eyes of
the scientific world were turned more intently on the subject. New
experiments were made, which corrected the old; and finally, on the
measurement of the arc in Peru, and in the north, truth and Newton
triumphed, and the equatorial diameter was found to exceed the polar
by a two hundred and fourth part of the whole. This was perhaps the
finest problem ever solved by science; the most perplexing in its
early state--exhibiting for a while the strongest contradiction of
experiment and theory, occupying in a greater degree the attention of
philosophers than any before or since, and finally established with a
certainty which every subsequent observation has only tended to
confirm. And this triumph belonged to an Englishman.

The investigation by measurements has since been largely adopted. In
1787, joint commissions were issued by England and France to connect
the Greenwich and Parisian observations. Arcs of the meridian have
since been measured across the whole breadth of France and Spain, and
also near the Arctic circle, and in the Indian peninsula.

In navigation, the grand point for the sailor is to ascertain his
latitude and longitude; in other words, to know where he is. The
discovery of the latitude is easily effected by the quadrant, but the
longitude is the difficulty. Any means which ascertained the hour at
Greenwich, at the instant of making a celestial observation in any
other part, would answer the difficulty; for the difference in
quarters of an hour would give the difference of the degrees. But
clocks could not be used on shipboard, and the best watches failed to
keep the time. In the reign of Anne, Parliament offered a reward of L.
5000, perhaps not far from the value of twice the sum in the present
day, for a watch within a certain degree of accuracy. Harrison, a
watchmak