8 



record given by the dredge and log to be 7,994,092, while from other observations I am positive 

 thai at least 2,000,000 oysters were taken from those beds in six days at the commencement of 

 the oyster season. Such could hardly have been the case had there been but 8,000,000 oysters 

 on the beds, and consequently, we must regard the " number of oysters to the square yard," as 

 shown by the method used, only valuable as establishing an initial number and standard by which 

 the increase or decrease of oysters on the beds may be ascertained, and by which one bed or 

 locality can be compared with another. Alone, the results of the dredge and log are valueless. 



TEMPERATURE OF THE WATER. 



It was originally intended that the temperature of the bottom water should be obtained by 

 means of thermometers attached to the "drop cylinders" used for obtaining the specimens of water 

 from the bottom, and six of those cylinders were fitted at the office with mercurial thermometers, 

 inclosed within the spindle upon which the cylinder moves, the bulb of the thermometer being a 

 little above the center of the cylinder when closed on the lower disk, and the graduated stem being 

 exposed above the top, thus allowing the temperature to be read within any limits that would 

 probably occur. 



Under the direction of the assistant in charge of the office, a series of experiments were made 

 by Mr. H. W. Blair, in order to ascertain the correction to be applied to the thermometers when 

 moved through strata of water of different temperatures, and from water of one temperature into 

 the air at another. With tables of corrections derived from those experiments, and with care in 

 using the apparatus, we hoped to arrive at results that would be very nearly correct, but 1 regret 

 to say that upon the first occasion when the cylinders were tried the thermometers were shown to 

 he useless. 



The cylinder is closed upon the lower metal disk by means of a spiral brass spring, which also 

 holds the cylinder down firmly, thus preventing the escape of the specimen. The spring acts with 

 considerable force, and we found that invariably the shock of the closure of the cup was sufficient 

 to break the mercurial column and prevent any reading of the thermometer. Attempts Mere luade 

 on board the vessel to remedy the evil by diminishing the strength of the spring, and by placing a 

 rubber buffer on the lower disk, but we were unable to prevent leakage, and subsequently the 

 same difficulty was experienced at the office. 



Owing to the failure of the thermometers in the water cylinders, and the inability to obtaiu 

 any apparatus, at so short a notice, in time to be available for the season's work, we were forced to 

 use ordinary unprotected thermometers, furnished by the Coast Survey Office, with corrections 

 established by experiments made previously and subsequently to the work of the party. The 

 thermometers were fastened to a lead, lowered to the bottom, and kept there a sufficient time to 

 acquire the temperature of the surrounding water. They were then hauled up as rapidly as possi- 

 ble and the temperature read ; at the same time the temperatures of the air and surface water was 

 noted. 



Owing to the rapid change of reading when the thermometers were moved through strata of 

 different temperature, the observations are only reliable when the temperatures of the air, surface, 

 and bottom water were identical. 



As the investigation extended over so short a period of time, and as the spawning season had 

 closed before we arrived on the ground, the recorded temperatures are of little interest, aud have 

 been omitted in the following papers. 



NAMES AND AREAS. 



In naming and describing the beds I have used the local names given them by the oystermen. 

 The term "rock" is with them synonymous with "bed," as they regard only the solid portions of 

 the area covered by the oysters. In the following pages the term "rock" indicates the solid, or 

 approximated solid, portions of the bed. Areas are given in feet and miles. When the latter unit 

 is used it is the nautical mile of 0,080 feet, and not the statute mile. 



