188 History of the Discovery of the Planet Neptune. 
half a minute of space; and now the error exceeds two minutes, 
This is equal to one fifteenth part of the apparent diameter of the 
sun or moon, which though small in itself, is large when compa- 
red with the precision of modern observations. What could be 
the cause of these discrepancies? Were the tables computed in- 
accurately? The errors were too large, and Bouvard was too 
skillful a computer, to permit. such an explanation. Were these 
discrepancies due to the action of some unknown disturbing bo- 
dy? This idea was seriously entertained more than twelve _ 
ago by Bouvard, Hansen, Hussey, and some others. Mr. Hussey 
even proposed to compute an approximate ecm of the supposed 
body, and then commence searching for it with his large reflec- 
tor. Mr. Airy, now Astronomer Royal of Great Britain, at that 
time Professor in Cambridge, pronounced the problem > nor 
His words were: “If it were certain that there was any extran 
ous action upon Uranus, I doubt much the gag id of iam 
mining the place of the planet which produced it. J am sure tt 
could not be done, till the nature of the ic acureoiie was well de- 
termined from gee — revolutions ;” that is, till after 
the lapse of several ce s. 
This deliberate an from one who by common consent stood 
at the head of British mathematicians and astronomers, would 
have deterred any but the most daring mathematician from at- 
tacking the problem. Again in 1837, Mr. Airy repeats the same 
idea: “If these errors are the effect of. any unseen body, 7 will 
be nearly impossible ever to find out its place.” 
The first serious attempt to discover = place of this distr 
ing body, was made by a young man ( . C. Adams, 
bridge University) in England. It stunela be Peataon et that 
accordance with the Newtonian law of gravitation, every body 
in the solar system attracts every other; that the attraction of 
is proportioned to its quantity of matter; and that in 
the same body the power of attraction varies inversely as the 
square of the distance. In order therefore to compute the exact 
place of a planet, in its orbit about the sun, it is necessary not 
merely to regard the attraction of the central body, but also to al- 
low for the influence of all the other bodies of the solar system. 
Hitherto mathematicians had only aspired to compute the dis- 
turbing influence of one body upon another, when the magnitude 
and position of both bodies were known. But in t of 
Uranus, it was required to solve the inverse problem which Pro- 
fessor Ai iry had pronounced hopeless, viz., from the observed dis- 
turbances of one body, to compute "the place of the setnaiedl 
y. 
_ After taking his degree of Bachelor of Arts in January, 1843, 
with. the honor 
of Senior —— Mr. iat Hevncnaiy ia to at- 
