To measure longer distances by walking the dividers...
(1) Set divider tips to a convenient whole unit such as 1.0 or 2.0 miles
(2) Start at the first point and "walk" the dividers along the route, counting the total number of steps.
(3) At the end, squeeze the divider tips together to measure the last, smaller step.
(4) Take dividers back to the lat scale or to a miles scale to measure the size of the last step and add this to the total number of steps for the full distance.

General Notes
This is the standard method for measuring longer distances. In most cases, you must balance out the best choice for the step size. If it is too large, you will lose accuracy going around corners, but if it is too small it takes longer to measure.

On electronic charts, this measurement is typically done by setting up a route of multiple waypoints between the two end points. Then the route properties can be displayed which among other data will include the total distance from start to end. Such a route could be temporary or saved. The properties will include the bearing or course between waypoints as well as the time of transit based on some input speed.

This procedure can also be used to measure or estimate the time a trip will take. If traveling at 7 knots, set dividers to a spacing of 7.0 miles, then walk off the route. Each step is 1 hour of travel time.

Video Notes
This example shows measuring the distance between two buoys some distance apart. It starts down and around a peninsula, up a channel, and into a bay. Dividers are first set to a separation of 2.0 miles using the latitude scale and then walked along the path.

There are 5 whole steps along the route, and then the dividers are squeezed together to span the last step. When moved to the latitude scale, we see it is about 1.1 miles. The total distance is then 5 x 2.0 + 1.1 = 11.1 miles (that is, nautical miles).