334 Davis’s Report on the Nautical Almanac.. 
precepts for the computation of this problem. This was as early 
as the year 1767. Its appearance created a new era in navigation, 
to which it is now acknowledged to have rendered more essential 
service than any thing of the kind ever undertaken. But the old 
lunar method of Maskelyne was very defective, owing to the ex- 
isting state of astronomical science and instruments. As the in- 
struments of the seaman and the astronomer, however, were im- 
proved, and astronomy itself advanced, corresponding changes 
were made in the almanac, which, since its first foundation has 
always kept up with the progress of knowledge and art; if not 
pari passu, at least without lagging behind for any great length 
of time. : : 
It was discovered, soon after its publication was begun, that 
the work was destined to obtain general circulation as an astro- 
nomical ephemeris for the use of observatories, and that it would 
be impracticable, even if desirable, which it was not, to separate 
pursuits of practical science so closely allied to each other, and 
so effectually promoted by the same means. In the progress of 
time, therefore, as the pages of the almanac were multiplied and 
their contents varied to meet the wants and conveniences of 
harmoniously united and benefited by similar provisions. 
o these considerations the “Nautical Almanac and Astro- 
nomical Ephemeris’” is indebted for its present character and 
condition. - 
On one hand, it is the text-book of the navigator. It informs 
him of his place on the ocean, where there are no other guides 
than the sun and stars. It is his intellectual rudder and compass; 
without it no ship-master leaves the shores of the United States. 
When he loses sight of the last light-house or head-land, he turns 
to that for his further direction. 
n the other hand, it is the vade mecum of the astronomer, 
whether stationary or travelling. He learns from it in the 4 
observatory how his instruments must be set that he may see any 
particular body, and what is the precise moment for observation: 
and in the movable observatory he turns to its pages to ar 
how, on any given day, he can best determine his latitude ant 
longitude, the astronomical bearings of his stations, and the ra 
and error of his chronometer. Thus, as the tables of the 
nhac owe their origin to the labors of the observatories, 5 ars : 
eS ee 
