XXXIJ 
REPORT—1847- 
tnunicacing liis wisdom to you on u most important nnd interesting dlicovcry 
of the past year: — 
“ In the lunar theory a very important step Iins been made in the course 
of the past year. When, near the beginning of the present century, a cod* 
siderable number of the Greenwich lunar observations were reduced by Burg 
for the purpose of obtaining elements for the construction of his Lunar 
Tables, and generdly for the comparison of the moon’s observed place with 
Laplace’s theory, it was found impossible to reconcile the theoretical with 
tl^ observed places, except by the assumption that some slowly varying error 
affected the epoch of the moon's nscan latitude. From the nature of the 
|Kocesa by which the errors of the elements are found, the conclusion upon 
the existence of this peculiar error is less stihjcct to doubt than that upon 
any other error. So certain did it appear, that l^placc devoted to it one 
entire chapter in the Mecaniqtu: CcUUe, with the title ‘On in inequality of 
ong period by which the moon's mean moiioii appears to be affected.' Guided 
by the general analogy of terras producing inequalities of long iieriod, he 
suggested as its probable cause an inequality tvhosc argument depends ution 
corahinaiion of the longitude of the earth's perihelion, the Iod* 
Soon’« T '""U^ude of the moon's node, and the 
hs no w calculate 
Sible differetirp suggested an inequality depending on a jxjs- 
vearstlCrh hemispheres of the l adb. .Many 
examined hv nliv«f siigge.stud llicorelical inequalities were carefully 
metKorer^hli^ P I At length the? imroduction of 
SS ofle successfully to enter upon the inves* 
ing on the argumentK 'i Proved that inequalities depend- 
The l>y Laplace could not have'sensible vilues. 
ondje^ac^curacy of the reduftions of 2 oSrVnJ^on’s. 
the Uritish^cLverSin atThe members of the British Association, 
the complete rediictjon,’on an Association, sanctioned 
moon made at the Koval OK observations of the 
and the imn.edi.,o4e^hlt° d Greenwich since the year 1730: 
troiioiner Royal. The redttcfJone ttndertakcn by the As- 
and the press-work is at this time verv in all necessary detail; 
the corrections of the elements of fKA^ *•■*** tummer 
and the errors of epoch in particular generally obtained; 
accuracy. 7 hese results confirmed tim found with great 
he mequality to a much UlL ^t^bJed the law of 
t- Aationoraer Royal to Prof. exhibited by 
gaged m the Lunar Theory Prof II "’Lo was known to be en- 
for their theoretical causes 1 'btmcaiately undertook a search 
Ty ‘bnr at rW Tn . of the suite of the ex- 
This ^ ® of the nhnefi a"* f ‘^***'*^ disturbances 
se irc^ P'-oLably hrfound ’r"' the explanation of 
mZ^: ‘"‘^^“•'‘Htfes of loni nlr ?d * of a systematic 
force of v" *^bgth two were found ^ound ; but none of sensible 
produced by the disturbing 
^ times 2 mein «pon the 
same rate arth^ '‘'"omaly of the Kartiri’n^ 
period "’•rP mmraaly of the Moo « very nearly the 
years. 1 he other l^epends upon ‘the* 
t wpon the circumalancc, that eight 
