8 THE RELATION OF PLANTS TO TIDE-LEVELS 
Survey. Since, however, the scale of the map (plate 1) is 1: 4,000, the metric 
value of any horizontal distance may readily be obtained by applying a metric 
scale directly to the map. 
After the stakes along the two main axes were in place, stakes were set along 
the east and west sides of the harbor and over the Marsh and Spit to serve as 
range-stakes. The stakes along the sides of the harbor were set due east and 
west of the stakes of the north and south axis, by means of a mariner’s quadrant. 
This is the only instrument that can be satisfactorily used in a floating boat. 
Stakes were placed by the aid of the same instrument, at 200 feet and 400 
feet south and 200 feet north of each stake in the main east-and-west axis 
across the Marsh. A line of stakes at 200-foot intervals by measurement 
was run westward on the Sand-spit from the stake in the main north-and-south 
axis, at 2,600 feet north. Range-stakes were then set at 400 feet south of each 
of these. A similar line was run eastward from the stake at 2,800 feet north in 
the north-and-south axis. A range-stake was then placed 200 feet south of each 
of these. 
When all these stakes were in place, by sighting with the aid of a field-glass 
one could determine the position of points in the harbor which were in range 
with any two stakes in the same north-and-south line, or of any two in the same 
east-and-west line. By measuring perpendicularly to these range-lines with a 
tape, the position of any point about the harbor with reference to any range-line, 
and so with reference to the main north-and-south and east-and-west axes, could 
be determined. By the intersection of the range-lines passing through the 
stakes of the longitudinal series with lines passing through the stakes of the 
transverse series, the harbor was divided off like a checker-board into squares, 
each square being 200 feet on a side. This is shown clearly on the map, where 
there is indicated by an xX each intersection which was actually marked by a 
stake in the harbor, on the shore, the Marsh, or the Sand-spit. 
_ ‘The first work to be done after the harbor had been staked off was to correct 
in detail the outline of the harbor, with its surrounding beaches, marshes, and 
wharves. The heavy solid-black boundary line, shown on the map, indicates the 
8-foot tide-line, wherever the harbor is bordered by the natural sloping beach 
or marsh. The portion of the shore-line bordered by the vertical walls of stone 
wharves, which vary in height from 7 to 9 feet, is indicated by the addition of 
short transverse lines to the heavy line of the 8-foot level. The exact outline of 
the shore on the east and west sides of the harbor was determined by measuring 
with a tape on each transverse range-line the distance of the shore-line east or 
west of the nearest north-and-south range-line, and so, practically, the distance 
east or west of the main north-and-south axis. Where the shore line is irregular 
measurements were made at several points between the successive east-and-west 
range-lines. The points so determined were plotted in on the map. With this 
map in hand in the field a line was drawn connecting these points and showing, 
as accurately as possible, the minor irregularities of the shore-line between the 
measured points. 
The method of marking the shore-line on beach and marsh, when the water 
was at the 8-foot level, was the same that was used for determining and marking 
other tide-levels, and will be described below. 
The locations of plants or the boundaries of plant groups growing on shore 
or on accessible parts of the harbor bottom were usually measured by rod or 
