Alexandria advertiser and commercial intelligencer. [volume] (Alexandria [Va.]) 1800-1803, 1803-09-12
LONGITUDE.

.. a have vestured on long voyages.
The poyeromenr Of Spain, of Holland,
and Of Great Britain, have successfully Of
Cred very considerable rewards to the per-
-, who should make the discovery. At
..mn,s have been made to effect this great
aesid.ratum by means Of time keepers, by
lunar observations, and by various osher
methods.
The person to whom science is SO great
h Obliged, and who is now prepared 70 lay
bis discoveries open 70 the public, is Mr.
Edward fIewings, a man distinguished by
his great scienti6c abilities, and patfanized
by some Of the first characters in this king
aou, His plan he executes without the
aid Of tugonometry, Of geometry, OF To-
garithms. or of time pieces. 1t IS per-
Sormed BY an instrument and tables, which
Nv INSPECTION only direct the course TO
steer. and what distance the seaman IS
from lis Intended port, when driven out
ofhis course by storms, when carried by
current, when he has lost his reck-
oning, or any other accident shall hap
pen.
These tables exhibit plain traverse, and
great circle sailing at sight. They give
the longitude in time from the meridian OF
the departure to the ships place; and also
between the meridian Of any two capes or
harbors, in any latitude, by means of the
old longitudinal tables, every degree IN
every latitude being reduced into sixty
geographical minutes, as on the equator
which may be applied to Hadley's quad
rant, the real quadrant, or any other quad
rant, sextans, compass, sc. &c. They
also give at sight the number of degrees,
minutes and seconds to any time proposed
by the earth'srevout.on on its axis, reck-
ouiag sixty geographical minutes TO de-
gree in every latitude, and will read Of in
every place in the same manner as or the
equator.
There are also tables. giving the diane
Ter of the globe in every latitude to prove
the true proportion of the paraliax; with
new Azinuth tables, and tables for the
right ascension of the sun; tables tor CIV
Ing the moons centre from the sun and
from the fixed stars, when either of them
are under the horriz IN, or at so great
distance that the angle cannot be taken by
anu suc fr,,p,an+ srovr y, .ssopd fhfc m
any latitude required, with the merdian
distance the longitude in time, and the
departure. There are also tables Of chords
laid down on the arch on the fine of 90 de-
grees (which, by the confession of the
greatest mathematicians and teachers OF
astronomy, has been wanting Tor nearly
1000 years) and graduated off IN every
latitude, in order to read OFF the chord ac-
cordlng to the paralax and to the moons
variable motion; which true parallax IS
gwen IN these tables of Mr.. Hewlings, so
that the time and chord should correspond,
anc De given at the same Instant. The
Instrument will shew the variation of the
Compass, and the re.raaion which hath
taken place in every latitude and the
distance of TIE moons centre from the
sun, to every day, hour. minute and second
Of lAesa and equased time. also of the fix
"a stars.
there are likewise tables ofequallzati-
on OF mean, tropical, and spherical time,
which are calculated for every day, hour,
minute and second of time, being worked
% the trilexf6 par Of q second, * in which
.ae demical parts are reduced to time,
leaving no fraction to any intermediate
ume. also the difference of mean and sy-
Cereal time, calculated in the same man.
nef as the tropical time, by which means
'ne difference of mean time, tropical time,
ana syderical tame, is given at any period
required.
Astronomers and teachers of the mathe-
mates have maintained the impossibllity
y reducing the dem'cal parts, which the
sSS'kn as a reason why the true time can.