The foregoing description is sufficient to indicate the general
method of working, but the details will of course vary
according to the configuration of the shore and the course
taken by the float. Good judgment is necessary in deciding when
to move from one station to the next, and celerity in setting
up, adjusting the instrument, and taking readings is essential.
If the boatmen can be relied upon to keep their position near
the float, very long sights can be taken with sufficient
accuracy by observing the position of the boat, long after the
float has ceased to be visible through the telescope.
The lines of sight from each station should be subsequently
plotted on the 1/2500 ordnance map; the intersection of each
two corresponding sight lines giving the position of the float
at that time. Then if a continuous line is drawn passing
through all the points of intersection it will indicate the
course taken by the float.
It is very desirable that the observers should be able to
convey information to each other by signalling with the flags
according to the Morse code, as follows. The dashes represent a
movement of the flag from a position in front of the left
shoulder to near the ground on the right side and the dots a
movement from the left shoulder to the right shoulder.
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