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472
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termining the longitude to one degree of
a great circle, or 60 geographical miles;
of 15, Cool. if it determines the same to
two thirds of that distance; and 20,000 l.
if it determines the longitude to 3o
miles [xix. 606.], or one half of a de-
gree. Encouraged by the hopes of gain-
ing so considerable a reward, and willing
to benefit mankind by their labours, ma-
ny ingenious persons have applied them-
selves to the solution of this famous pro-
blem, the discovery of the longitude at sea ;
a problem which was formerly placed in
the same degree of probability with the
secret of prolonging life, the perpetual mo-
tion, and the suaring of the circle.

Among the many candidates for this

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Of the inventions for discovering the longitude. Vol. xxiv.;

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be produced, as, particularly, the manifest impropriety of taking observations on land for determining the going of the clock; fince the true time at the ship must always be determined at sea, by taking altitudes with Hadley's quadrant. But I shall at present content myself with saying, that the method now before us does not appear to me to be calculated to do justice even to Mr Harrison; since he has been prevailed on to undertake this voyage at a time when his watch is not brought to that degree of perfeótion which he is capable of giving it; and when he knows, or ought to know, that he is not allowed, by an amendment lately made of the 12th of Q. Anne, (if I am rightly informed), more than one trial. Though the method of determining the

Of the inventions for discovering the longitude.

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