10 
OYSTER BEDS OF JAMES RIVER, VIRGINIA. 
a clock under the observation of the recorder, the leadsman made a 
sounding and reported to the recorder the depth of water and the 
character of the bottom, immediately after which the man at the 
wire reported the character of the chain indications since the last 
sounding — that is, whether they showed barren bottom or dense, 
scattering, or very scattering growths of oysters. 
With the boat running at 3 miles an hour the soundings were 
between 80 and 90 feet apart and, as the- speed of the boat was uni- 
form, the location of each was determinable within a yard or two 
by dividing the platted distance between the positions determined 
by the sextant by the number of soundings. The chain, of course, 
gave a continuous indication of the character of the bottom, but the 
record was made at the regular twenty-second intervals observed in 
sounding. 
The chain, while indicating the absence or the relative abundance 
of objects on the bottom, gives no information as to whether they 
are shells or oysters, nor, if the latter, their size and condition. To 
obtain this data it was necessary to supplement the observations 
already described by others more definite in respect to the desired 
particulars. Whenever in the opinion of the officer in charge of the 
sounding boat such information was required, a numbered buoy was 
dropped, the time and number being entered in the sounding book. 
Another launch, following the sounding boat, anchored alongside 
the buoy, and a quantity of the oysters and shells were tonged up, 
separated by sizes, and counted. 
In former surveys made by the writer, in order to arrive at an 
estimate of the density of the oyster growth a definite area, usually 
5 yards, was staked off by means of steel-shod pikes and everything 
was removed from the bottom and counted. This method is accu- 
rate, but slow and difficult in deep water, and, as it was desirable to 
make a large number of observations, the system developed in the 
Maryland survey was adopted. This consists essentially in making a 
known number of “ grabs” with the oyster tongs, exercising care to 
clean the bottom of oysters as thoroughly as possible at each grab. 
In a given depth of water and using the same boat and tongs an oyster- 
, man will cover practically the same area of the bottom at each grab, 
but, other factors remaining the same, the area of the grab will 
decrease with an increase in the depth. 
Careful measurements were made and tabulated showing the area 
per grab covered by the tonger employed on the work at each foot of 
depth of water and for each pair of tongs and boat used. With this 
data, and knowing the number of “grabs,” the number of oysters 
of each size per square yard of bottom was readily obtainable by 
simple calculation. The following example will illustrate the data 
obtained and the form of the record: 
