PROCESSING BATHYTHEEMOGRAPH DATA AT THE EYDBOGEAPHIC OFFICE 



A. IKTEODUCTIOW 



In 1914-1 the U. S. Kavy expanded the program for taking bathythermo- 

 graph (BT) oTDservatlona. As a result, a system of processing these 

 observations was developed at Woods Hole Oceanographlc Institution and 

 at the University of California, Division of War Eesearch, Saja Diego. 

 This method has been followed with few modifications to the present 

 time. In general, tt consists of h steps: (1) recording; (2) plotting; 

 (3) photographing (printing); and {k) transcribing. These steps are 

 briefly described as follows: 



1. Becording consists of assigning a file designation or cruise 

 number and checking the slides and log sheets for proper entry of date 

 and other required Information. 



?. Plotting consists of plotting the position of each observation 

 and correcting the log sheet when necessary. 



3. Photographing (Printing) is carried out by superimposing a 

 transparent temperature depth grid on a slide and adjusting the rela- 

 tive positions of the grid and slide to correct for any instrumental 

 error. The superimposed grid and slide are used as a negative in making 

 the photographic prints (LaFond, 1951). 



k. Transcribing is the most time consuming of all steps (Leipper, 

 19^8). It consists of stamping, the back of each print to provide 

 spaces for entering pertinent meteorological and other data. Then 

 log sheet data are copied by hand onto the back of each print. 



The stamping was eliminated in 1950 "when lii5)rlnted photographic 

 paper became available (Schroeder, 1955). 



In 19^7 a transparency method was proposed by Scripps Institu- 

 tion of Oceanography In which the slides were imposed upon transparent 

 sensitized paper (Leipper, 19^7)' A space was provided on an unused 

 portion of the slide and grid where the log sheet data were inserted 

 and exposed separately. The transparent paper was then developed in 

 the usual manner and additional prints could be made by contact 

 printing. A negative became available by this method to make addi- 

 tional prints that required no additional transcribing of data. 

 Initial transcribing was necessary in preparation of the negative. 

 The method apparently was never extensively used. 



In 1953 a recording camera for reproduction of BT slide data 

 was developed by the Navy Underwater Sound Laboratory (Selvidio, 

 1953)- This type of light, portable equipment is very useful at 

 sea. It uses a small '^'^-nrni. , 3^-exposure still camera for photo- 

 graphing the slide and grid. The developed film can be viewed 



