The underlined figures on the dry banks represent in feet or fathoms the depth of water over them at High Water, or the heights of the banks above Low Water. The method adopted is explained in the Title of the Chart.

The Velocity of Tide is expressed in knots and fractions of a knot. The Period of the Tide being shown thus 1st Qr., 2nd Qr., 3rd Qr., 4th Qr., for 1st, 2nd, 3rd, and 4th Quarters.

The Rise of Tide is measured from the mean Low Water level of Ordinary Springs. The Range of Tide is measured from the Low Water of one tide to the High Water of the following tide.

All heights are given in feet above High Water Ordinary Springs, and in places where there is no tide, above the level of the sea.

All bearings, including the direction of winds and currents, are Magnetic; except when otherwise expressed. Bearings of Lights are given as seen from seaward, and not from the lights.

The natural Scale, or the proportion which the Chart bears to the earth, (obtained by reducing the number of feet in the minute of latitude to inches, and dividing the product by the number of inches to a mile the chart is drawn upon,) is represented thus 12150

A Cable's length is assumed to be the 10th part of a Sea mile, or equal to 100 fathoms.