with a large boat the observations can be pursued through
rougher weather, which is an important point, still the
difficulty of maintaining a large boat propelled by mechanical
power, or sail, sufficiently near the float to assist the
observers, prevents its use, and the best result will be
obtained by employing a substantial, seaworthy rowing boat with
a broad beam. The boatmen appreciate the inclusion of a mast,
sails, and plenty of ballast in the equipment to facilitate
their return home when the day's work is done, which may happen
eight or nine miles away, with twilight fast passing into
darkness. There should be two boatmen, or a man and a strong
youth.

In working with theodolites, it is as well before starting to
select observation stations at intervals along the coast, drive
pegs in the ground so that they can easily be found afterwards,
and fix their position upon a 1/2500 ordnance map in the usual
manner. It may, however, be found in practice that after
leaving one station it is not possible to reach the next one
before the time arrives for another sight to be taken. In this
case the theodolite must be set up on magnetic north at an
intermediate position, and sights taken to at least two
landmarks, the positions of which are shown on the map, and the
point of observation subsequently plotted as near as possible
by the use of these readings. Inasmuch as the sights will be
taken from points on the edge of the shore, which is, of
course, shown on the map, it is possible, after setting up to
magnetic north, to fix the position with approximate accuracy
by a sight to one landmark only, but this should only be done
in exceptional circumstances.