DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.20658#0367
PROJECTION.
353
from the points of division, draw lines to the centre, for the circles of longitude. Next divide
any circle of longitude, as.the first meridian, into nine equal parts, and through these points
■describe circles from the centre, for the parallels of latitude.
The advantage gained by this third method is, that equal spaces on the earth are represented
by equal spaces on the maps, or at least as nearly so as any projection will allow: for a spherical
surface can in noway be correctly represented on a plane. When this is done, the several
countries, seas, islands, coasts, mountains, rivers, towns, &.c. may be entered in the map, agree-
ably to their positions in latitude and longitude. In filling up the map, the places representing
land are filled with such things as the countries contain, but the sea is left white, the shores only
being shaded. Rivers are marked by strong or double lines, drawn in a winding direction, ac-
cording to their real form and course. The different countries are best distinguished by colouring
at least their boundaries; forests are represented by trees, and mountains are shaded to give an
idea of their elevations and the direction of their ranges. Sands are shewn by small dots or
points, and rocks under water by a small cross. And lastly, in some void space, the mariner's
compass, with the 3.Q points or winds, is laid down.
In drawing the map of any particular country or kingdom, England for instance, situated
•between the 50th and 56th degrees of north latitude, and between the 2d degree of east, and the
tith of west longitude, reckoned from Greenwich, the.map will comprehend 6 degrees of latitude
and 8 degrees of longitude.
First draw a line for a meridian passing through the middle of the map, which in this case,
will fall two degrees to the westward of Greenwich ; and divide it into six equal parts for the
degrees of latitude. Then draw two lines perpendicular to the meridian for the extreme parallels
of latitude 56 and 50 ; and other parallels for the intermediate degrees. To obtain the meridians,
divide a degree towards the middle into 60 equal parts, to represent the munber of geographical
miles contained in one degree, corresponding to about 6'9 ~Q English miles. Now asthelengUi
of a degree of longitude decreases according as the latitude Increases, in the proportion of the
co-sine of the latitude to radius, find the number of geographic miles in a degree of longitude at
latitude 50, and set it off at each hand : then will this line be divided into the due number of
degrees. In the same wav set off the number of miles composing:^ degree of longitude in lati-
tude 56, and through these divisions, on both lines, draw right lines to represent the meridians.
The degrees of latitude are numbered upwards on both sides of the map; and those of lon-
gitude along the top and bottom, beginning in the example here given at the meridian which
passes over Greenwich, and counting 1, <2, eastward, and 1, 2, 3, .4, 5, 6, westward. When this
is done, with the proper latitudes and longitudes, lay.down the several points of the coasts and
boundaries, the cities, towns,.harbours &c. .&c. and the map will be completed.
The course of rivers and the sea coast are laid down in the same wav, by the latitudes and
longitudes of their principal points,-anc [hen through ..these, drawing a waving line, to represent
their various windings.
A nother method.-—Maps of particular portions of the globe may be drawn in the same way
with one of the whole, either by the orthographic or stereographie projections of the sphere;
but for maps of-small portions there is an easier-method.— Having drawn a meridian and divided
it into equal parts, as in the last method, through all the points of division, draw perpendiculars
..for the parallels of latitude. Then to divide these set off the degrees of .longitude, not on the
4 x extreme
353
from the points of division, draw lines to the centre, for the circles of longitude. Next divide
any circle of longitude, as.the first meridian, into nine equal parts, and through these points
■describe circles from the centre, for the parallels of latitude.
The advantage gained by this third method is, that equal spaces on the earth are represented
by equal spaces on the maps, or at least as nearly so as any projection will allow: for a spherical
surface can in noway be correctly represented on a plane. When this is done, the several
countries, seas, islands, coasts, mountains, rivers, towns, &.c. may be entered in the map, agree-
ably to their positions in latitude and longitude. In filling up the map, the places representing
land are filled with such things as the countries contain, but the sea is left white, the shores only
being shaded. Rivers are marked by strong or double lines, drawn in a winding direction, ac-
cording to their real form and course. The different countries are best distinguished by colouring
at least their boundaries; forests are represented by trees, and mountains are shaded to give an
idea of their elevations and the direction of their ranges. Sands are shewn by small dots or
points, and rocks under water by a small cross. And lastly, in some void space, the mariner's
compass, with the 3.Q points or winds, is laid down.
In drawing the map of any particular country or kingdom, England for instance, situated
•between the 50th and 56th degrees of north latitude, and between the 2d degree of east, and the
tith of west longitude, reckoned from Greenwich, the.map will comprehend 6 degrees of latitude
and 8 degrees of longitude.
First draw a line for a meridian passing through the middle of the map, which in this case,
will fall two degrees to the westward of Greenwich ; and divide it into six equal parts for the
degrees of latitude. Then draw two lines perpendicular to the meridian for the extreme parallels
of latitude 56 and 50 ; and other parallels for the intermediate degrees. To obtain the meridians,
divide a degree towards the middle into 60 equal parts, to represent the munber of geographical
miles contained in one degree, corresponding to about 6'9 ~Q English miles. Now asthelengUi
of a degree of longitude decreases according as the latitude Increases, in the proportion of the
co-sine of the latitude to radius, find the number of geographic miles in a degree of longitude at
latitude 50, and set it off at each hand : then will this line be divided into the due number of
degrees. In the same wav set off the number of miles composing:^ degree of longitude in lati-
tude 56, and through these divisions, on both lines, draw right lines to represent the meridians.
The degrees of latitude are numbered upwards on both sides of the map; and those of lon-
gitude along the top and bottom, beginning in the example here given at the meridian which
passes over Greenwich, and counting 1, <2, eastward, and 1, 2, 3, .4, 5, 6, westward. When this
is done, with the proper latitudes and longitudes, lay.down the several points of the coasts and
boundaries, the cities, towns,.harbours &c. .&c. and the map will be completed.
The course of rivers and the sea coast are laid down in the same wav, by the latitudes and
longitudes of their principal points,-anc [hen through ..these, drawing a waving line, to represent
their various windings.
A nother method.-—Maps of particular portions of the globe may be drawn in the same way
with one of the whole, either by the orthographic or stereographie projections of the sphere;
but for maps of-small portions there is an easier-method.— Having drawn a meridian and divided
it into equal parts, as in the last method, through all the points of division, draw perpendiculars
..for the parallels of latitude. Then to divide these set off the degrees of .longitude, not on the
4 x extreme