OYSTER BEDS OF JAMES RIVER, VIRGINIA. 9 
METHODS OF THE PRESENT SURVEY. 
To furnish authoritative and definite information as to the actual 
extent and condition of the natural rocks and the character of the 
bottoms embraced within the boundaries of the public beds, it was 
necessary to depart widely from the methods of the previous surveys. 
It was decided to confine the investigation wholly to the public 
beds, passing their boundaries only far enough to give assurance 
that the entire area had been covered. Nothing was to be gained 
by an examination of the excluded areas, as it is now almost impos- 
sible to determine whether natural rocks were omitted from the 
grounds laid out in 1892, and it is too late to correct such omissions 
if they could be determined. For legal purposes, all that is not 
avowedly public ground is barren bottom, and if held under leasehold 
from the State can not be alienated from the possession of the lessees 
as long as the law has been complied with. 
The methods followed have been essentially those pursued in for- 
mer surveys conducted by the Bureau of Fisheries, with the changes 
and improvements dictated by recent experience and the local 
conditions. 
The Coast and Geodetic Survey furnished projections on which 
were platted the triangulation points used in former surveys by that 
bureau. Several of these points, including the light-houses, were 
“ recovered/’ and from them the signals, usually tripods, erected where 
necessary, were cut in and platted by means of the sextant and 
3-arm protractor. This method, while lacking the great precision 
attained by means of the best theodolites and the nice computations 
employed by the Coast Survey in its work, insures an accuracy more 
than sufficient for the purposes of an oyster survey. 
The oyster beds were discovered by soundings with. a lead line, 
but principally by means of a length of chain dragged over the bottom 
at the end of a copper wire running from the sounding boat. The 
wire was wound on a reel, and its unwound length was adjusted to 
the depth of water and the speed of the launch, so that the chain was 
always on the bottom. Whenever the chain touched a shell or an 
oyster the shock or vibration was transmitted up the wire to the hand 
of a man whose sole duty it was to give heed to such signals and 
report them to the recorder. 
The launches from which the soundings were made were run at a 
speed of between 3 and 4 miles per hour, usually on ranges ashore 
to insure the rectitude of the lines. At intervals of three min- 
utes — in some cases two minutes — the position of the boat was 
determined by two simultaneous sextant observations of the angles 
between a set of three signals, the middle one of which was common 
to the two angles, the position being immediately platted on the 
boat sheet. At regular intervals of twenty seconds, as measured by 
