SCIENTIFIC PREDICTION 187 



bility of the approaching discovery of a new planet 

 soon found expression in popular treatises on astron- 

 omy. Mrs. Somerville in her book on The Connec- 

 tion of the Physical Sciences (1836) said that the 

 discrepancies in the records of Uranus might reveal 

 the existence and even " the mass and orbit of a body 

 placed for ever beyond the sphere of vision." Simi- 

 larly Madler in his Popular Astronomy (1841) 

 took the view that Uranus might have been pre- 

 dicted by study of the perturbations it produced in 

 the orbit of Saturn. Applying this conclusion to a 

 body beyond Uranus we, he continued, " may, in- 

 deed, express the hope that analysis will one day or 

 other solemnize this, her highest, triumph, making 

 discoveries with the mind's eye in regions where, in 

 our actual state, we are unable to penetrate." 



One should not pass over in this account the labors 

 of Eugene Bouvard, the nephew of Alexis, who con- 

 tinued to note anomalies in the orbit of Uranus and 

 to construct new planetary tables till the very eve 

 of the discovery of Neptune. In 1837 he wrote to 

 Airy that the differences between the observations 

 of Uranus and the calculation were large and were 

 becoming continually larger : " Is that owing to a 

 perturbation brought about in this planet by some 

 body situated beyond it? I don't know, but that's 

 my uncle's opinion." 



In 1840 the distinguished astronomer Bessel de- 

 clared that attempts to explain the discrepancies 

 " must be based on the endeavor to discover an orbit 

 and a mass for some unknown planet, of such a na- 

 ture, that the resulting perturbations of Uranus 

 may reconcile the present want of harmony in the 



