324 Davis’s Report on the Nautical Almanac. 
out the continent of Europe, and in all parts of North America, 
and thus affording occasion for numerous and very valuable tests, 
was seized upon to compare the moon’s observed place with the 
tabular place derived from the American tables, yet the calcula- 
tion of eclipses is very far from being a chief part, but on the 
contrary, is an inferior and secondary part of the business of the 
almanac. It occupies a very small portion only of the time and 
labor of the computors, and a very humble place in the pages of 
that comprehensive work. 
t may be mentioned among the. benefits conferred by these 
lunar tables, that they bring into practical availability a large num- | 
ber of “moon culminations,” as they are technically calied, ob- 
served by the astronomers of the coast survey on the western 
coast of the United States, which have been hitherto lost. . These 
observations are made on the land for the nice and accurate de- 
termination of geographical longitudes, and in that now difficult 
- and extensive field of labor, are of the highest importance ; 
owing, however, to the imperfections in the tables by means of 
which the place of the moon in her orbit is computed, no other 
observed “‘ moon culminations” can be usefully applied than those 
which have been correspondingly observed elsewhere. ‘That 18, 
these “moon cu!minations,” to be available, must be observed at 
the same date at two different places. In consequence of this 
necessity some six hundred or more of the observations made‘in 
California and Oregon, to be found in the books of the coast sur- 
vey, have been laid aside “for want of moon’s places more reli- 
able than the British Nautical Almanac can give us.” (Letter of 
A. D. Bache, superintendent United States Coast Survey, to the 
superintendent of the Nautical Almanac, November 20, 1851.) 
These more reliable moon’s places, such as are sufficiently ac- 
curate for immediate comparison with observation, being given 
by the new tables of the Nautical Almanac, the heretofore un- 
available “moon culminations” are made at once to serve thet 
original purpose, and the determination of numerous geographical 
positions in our recently acquired territory on the Pacific 1s ren- 
dered more expeditious and more complete. a a : 
It was said that the ephemeris of the planets has been 1m- 
proved. ‘The ephemeris of the planet Mercury will be derived, 
for the first time, from the new and elegant theory of M. Le 
Verrier. 
In preparing the ephemeris of Venus, with that of Mars, the 
correctness of Lindenau’s elements of the orbits of these planets 
educed from the Greenwich planetary observations from 1750 to 
1830, by Mr. Huh Breen, have been for the first time introduced. 
But some labor has been bestowed in combining the rough group- 
ings of Mr. Breen in such a manner as to carry forward the cor 
rections uninterruptedly ; all his results have also been discuss®™ 
