If the Degrees of Latitude are to be augmented as much as those of Longitude are found enlarged by making them equal to the Degrees of the Equinoctial, the Secants must be used, which increase in the same Proportion as the Sine-Complements of the Latitudes (which ought to represent the Degrees of Longitude) have been increased, by making them equal to the Radius of the Equator, because of the Parallelism of the Meridians: for the Sine-Complement of an Arc is to Radius, as Radius is to the Secant of that Arc.

As, assuming for one Degree of the Equator, and for the first Degree of Latitude, the whole Radius, or some aliquot part thereof; take for the 2d Degree of Latitude, the Secant of one Degree, or a similar aliquot part of this Secant; and for the 3d Degree of Latitude, take the Secant of two Degrees, or the similar aliquot part thereof, and so on.

When a Chart is to be made large, you must take, for 30 Minutes of Latitude, and 30 Minutes of the Equator, the Radius of a Circle or some aliquot part thereof, for one Degree of Latitude. This being done, you must add continually the Secant of 30 Min. for 1\(\frac{1}{2}\) Degree of Latitude, the Secant of 1 Degree for 2 Degrees of Latitude, the Secant of 1\(\frac{1}{2}\) Degree for 2\(\frac{1}{2}\) Degrees of Latitude, or their similar aliquot parts; and so proceed on. In doing of which, we use a Scale of equal parts, from which the Secants as they are found in Tables are taken off, by taking away some of the last Figures.

In these Charts the Scale is changed, according as the Latitude is; as, for example, if a Ship fails between the 40th and 50th Parallel of Latitude, the Degrees of the Meridians between those two Parallels will serve for a Scale to measure the Ship’s Way; whence it follows, that there are fewer Leagues on the Parallels, the nearer they are to the Poles, because they are measured by a Magnitude likewise continually increasing from the Equator towards the Poles.

If, for example, a Chart of this kind be to be drawn from the 40th Degree of North Latitude to the 50th, and from the 6th Degree of Longitude to the 18th: First draw the Line AB, representing the 40th Parallel to the Equator, which divide into twelve equal Parts, for the 12 Degrees of Longitude, which the Chart is to contain. Tins being done, take a Sector or Scale, one hundred Parts whereof are equal to each of these Degrees of Longitude, and at the Points A and B raise two Perpendiculars to AB, which will represent two

parallel Meridians, and must be divided by the continual Addition of Secants. As, for the Distance from 40 Deg. to 41 Deg. of Latitude, take 131\(\frac{1}{2}\) equal Parts from your Scale, which is the Secant of 40 Deg. 30 Min. For the Distance from 41 Deg. to 42 Deg. take 133\(\frac{1}{2}\) equal Parts from your Scale, which is the Secant of 41 Deg. 30 Min. For the Distance from 42 Deg. to 43 Deg. take 136, which is the Secant of 42 Deg. 30 Min. and so on to the last Degree of your Chart, which will be 154 equal Parts, *viz.* the Secant of 49 Deg. 30 Min. and will give the Distance from 49 Deg. of Latitude to 50 Deg. and by this means the Degrees of Latitude will be augmented in the same Proportion as the Degrees of Longitude on the Globe do really decrease.

Having divided the Meridians, you may place the Card upon the Chart, for doing of which, chuse a convenient Place towards the Middle thereof, as the Point R, about which, as a Center, describe a Circle so big that it’s Circumference may be divided into 32 equal Parts, for the 32 Points of the Compass. Then having drawn a Line towards the Top of the Chart, parallel to the two divided Meridians, this will be the North Rhumb, and upon it a *Flower-de-Luce* must be put, that thereby all the other Rhumbs or Points may be known, the principal of which ought to be distinguished from the others by broader Lines.

After this, all the Towns, Ports, Islands, Coasts, Sands, Rocks, &c. which form the Chart, must be laid down upon the same, according to their true Latitudes and Longitudes. And if the Chart be large, there may several Cards be placed thereon, always with their North and South Lines parallel between themselves.