Examined in this way the tabulated observations of Flamsteed showed that
he had unwittingly observed Uranus five distinct times; the first time
in 1690, nearly a century before Herschel discovered its true nature.
But more remarkable still, Le Monnier, of Paris, had observed it eight
times in one month, cataloguing it each time as a different star. If
only he had reduced and compared his observations, he would have
anticipated Herschel by twelve years. As it was, he missed it. It was
seen once by Bradley also. Altogether it had been seen twenty times.
These old observations of Flamsteed and those of Le Monnier, combined
with those made after Herschel's discovery, were very useful in
determining an exact orbit for the new planet, and its motion was
considered thoroughly known. For a time Uranus seemed to travel
regularly, and as expected, in the orbit which had been calculated for
it; but early in the present century it began to be slightly refractory,
and by 1820 its actual place showed quite a distinct discrepancy from
its position as calculated with the aid of the old observations.
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