CHART. 
and numbered accordingly. From each 
end of this line perpendiculars are to be 
drawn, and made equal to the intended 
extent of the chart from east to west, and 
their extremities are to be joined by a 
straight line. If the chart is to commence 
at or near the equator, and to extend only 
a few degrees of latitude, the divisions of 
the parallels may be equal to those of the 
meridian : but if the chart begins at any 
considerable distance from the equator, it 
will conduce to accuracy, to make the 
length of each degree of the parallel equal to 
the co-sine of the mean latitude, the radius 
being 60 minutes ; or the extreme parallels 
may be divided according to the above 
proportion, and in that case it will become 
a reduced chart. Meridians and parallels 
are there to be drawn at convenient dis- 
tances. 
A scale is now to be made of stiff paper 
or pasteboard, equal in length to the ex- 
tent of the chart from east to west, and 
divided and numbered accordingly- By 
this scale, the positions of those places con- 
tained within the limits of the chart are 
very easily laid down, by placing the di- 
vided edge of the scgle over the latitude 
of the given place -, and under the given 
longitude, a mark being made will repre- 
sent the position of the place on the chart. 
A compass is to be inserted in any con- 
venient place of the chart, an arrow shew- 
ing the direction of the flood tide or cur- 
rent. The times of high water at foil and 
change are to be marked in their proper 
places, expressed in Roman characters; 
sounding and quality of the ground at bot- 
tom, the leading marks to ayoid dangers, 
&c. 
II. Of a Mercator's chart . — A Mercator’s 
chart, for any given portion of the surface 
of the globe, is constructed as follows : 
the limit of the proposed chart is first to be 
determined, that is, the number of degrees 
of latitude and longitude which it is to con- 
tain, and the degree of latitude and longi- 
tude of its commencement. Find the me- 
ridional parts answering to each degree of 
latitude, within thp intended limits of the 
chart, and take tlie difference between 
each, and that corresponding to the least 
degree of latitude in the chart; and reduce 
these differences to degrees, by dividing 
by 60. 
A parallel, representing that of the least 
latitude, is to be drawn; upon which the 
number of degrees in the proposed diffe- 
rence of longitude, from a scale of equal 
parts, is to be laid oflF, and divided into de- 
grees, and smaller portions of, if convenient, 
and numbered at eaph fifth or tenth de- 
gree. From each end of this parallel, a 
perpendicular is to be drawn, and made 
equal to the difference of the meridional 
parts of the extreme latitudes taken from 
the divided parallel ; and the ends of these 
meridians aie to be joined by a straight 
line, which will rejiresent the other extreme 
parallel, and which is to be divided and 
numbered in the same manner as the first 
drawn parallel ; the meridians are then to 
be divided into degrees, and numbered at 
every fifth or tenth degree. Take the me- 
ridional difference of latitude between the 
beginning of the chart, and tlie pext fifth 
or tenth degree oflatitude from the divided 
parallel, and lay it off from the first parallel 
on each of the scale meridians, and join 
these points by a straight line. In like 
manner the meridional difference of lati- 
tude answering to each successive interval 
of five or ten degrees, is to be taken from 
the first drawn parallel and laid off, and 
tlie corresponding parallels are to be drawn 
and nqmhered accordingly, and the inter- 
mediate spaces are to be subdivided. If 
the chqi't is upon a large scale, the meri- 
dional difference of latitude answering to 
each degree, is to be laid ol^ from the least 
parallel. 
If the chart is intended to be upon a 
larger scale, equi-multiples of the intervals 
are to be taken, such as will answer to the 
proposed extent of the chart. A slip of 
strong paper is to be divided, and num- 
bered in the same manner as the first dravvri 
parallel. Now each place within the limits 
of the chart is to be laid down, by placing 
the slip of paper, so that its extreme points 
of division may be at tlie latitude of the 
given place on each meridian ; then, under 
the longitude of the place a mark is to be 
made, which will represent the position of 
that place. In like manner all the places 
on the coast arc to be laid down, and con- 
nected by observations made on the coast j 
or if no sketch had been previously made, 
the contour of the coast is to be drawn 
agreeable to the best charts. Meridians 
and parallels are to be drawn through every 
fifth or tenth degree of latitude and Icngi. 
tude, and extended to the coast. 
A compass is to be inserted in some con- 
venient part of the chart, and the points 
extended to the land : an anchor is to be 
drawn where there is good anchoring ground, 
and in places where it is safe only to stop 
