D. P. Todd—Search for a Trans-neptunian Planet. 238 
] 
pected objects. On the succeeding night of observation these 
objects were re-observed: and, at an interval of several weeks 
thereafter, the observation was again verified. t 3 A. M., the 
h of March, 1878, the search was discontinued—my observ- 
ing-book ends with the following note 
‘The adopted plane of orbit of trans-neptunian planet is now 
searched (without break) from 
= 1456's 
to v = 186°°1.” 
I have much confidence in this telescopic search—my aim 
was to sweep the zone so carefully that there should be no 
pressing need of duplicating it. If a trans-neptunian planet of 
an apparent diameter, so great as 2’ is ever discovered, I shall 
be much surprised if it is found that it must have eluded my 
search. 
ery soon after the termination of this search, I received 
the new tables of Uranus, by the late LeVerrier.* I at once in- 
stituted a treatment of the residuals of these tables after the 
method employed with those of Newcomb. I merely mention 
here that I reached a result entirely confirmatory to that pre- 
viously obtained. The residuals were first reduced to New- 
comb’s mass of Neptune. 
T ought not to conclude this paper without adverting to the 
apparently long delay of its publication. From the very be- 
earlier realization—it seeming improbable that any sie chance- 
i Aft 
rch. 
with the residuals of Uranus only in the hope of a possible 
Shortening of the search by some indication that the 
* Annales de l’Observatoire de Paris, Mémoires, vol. xiv. 
