14-47 L-Z or Cosine (Z/L).— Tlie two 



columns under this headint; are used to deter- 

 mine the accepted depths by either the L-Z or 

 the cosine (Z/L) method. These methods are 

 described in chapter H. Indicate the method 

 used by crossing out the other method. 



(a) Ohs. — In this cohimn are recorded the 

 L-Z or ZjL observed vahies. In the L-Z 

 method, as shown in figure 14-2, tlie vaUies 

 recorded in this column are tlie differences be- 

 tween the Wire Depth (i) and the Ther- 

 mometer Depth (Z). These values for the 

 station are plotted on graph paper, as shown 

 in figure 3-4, and curves drawn. 



(6) Used. — In this column are recorded the 

 L-Z or ZjL values interpolated from the 

 curves constructed for all the bottles on one 

 cast. These values are actually used to de- 

 termine the accepted depths. 



14-48 Accepted Depth. — The Accepted 

 Depth is the best possible determination of the 



true depth of each Nanscn bottle at the time of 

 reversal. With the L-Z, method, the accepted 

 depth is obtained by subtracting the value 

 listed in the preceding Used column from the 

 Wire Depth (L). The values in this column are 

 recorded on the E-sheet in tiie column headed 

 Accepted Depth, along with their corresponding 

 serial numbers and temperatures. 



14-49 Remarks. — Record in the Remarks 

 column any comments that may be useful in the 

 analyses of data. Such items as thermometers 

 malfunctioning, Nansen bottles failing to trip, 

 unusual weather or sea conditions, etc., are VL'ry 

 useful in later analvses. 



14-50 ASSOCIATED OBSERVATIONS.— 

 All other observations taken on the station 

 should be recorded at the bottom of the A sheet. 

 These would include bottom samples, biological 

 specimens, transparency measurements, wave 

 staff observations, etc. 



OCEANOGRAPHIC LOG SHEET B, PRNC-NHO-1189 

 (Rev. 12-53) 



BATHYTHERMOGRAPH OBSERVATIONS 



14-51 GENERAL REMARKS. The B- 



sheet is used to record all bathythermograph 

 observations. General operating instructions 

 are given in chapter 2. 



14-52 Special Instructions. — During the 

 course of a U. S. Navy survey, a great many 

 bathythermograph observations are usually 

 taken. Routine observations are made every 

 hour and frequently observations are required 

 as often as every 10 or 15 minutes. As special 

 studies usually are made from these observa- 

 tions, the instructions given below for filling in 

 the log sheet applv to U. S. Xavv survevs. 



14-53 The Term BT.— Through widespread 

 usage the term BT has become the shortened 

 name for bathythermograph. The term BT 

 sluill be used in these instructions. 



14-54 THE LOG SHEET.— A sample log 

 sheet is shown as figure 14-3. Print all entries 

 accurately and neatly. Record complete in- 

 formation for every BT observation. Fill in 

 everv space. Do not use ditto marks. 



14-55 The Log Sheet Headings. Fill in 

 the ship's name and number, the month, and 

 the year at the top of the sheet. Write the 

 cruise name and number above the space for 

 Vessel. Number the log sheets consecutively 

 above the space for Time Zone, as shown in 

 figure 14-3. Use Greenwich mean time 



(GMT) for all BT observations. In the space 

 marked Time Zone indicate the local time zone 

 in which the ship is operating. 



14-56 The Log Sheet Columns. — As soon 

 as possible after eacii BT lowering the log sheet 

 columns should be completed in accordance 

 with the instructions given below. 



14-57 Serial No. — Each observation re- 

 ceives a serial luimber commencing with nu- 

 meral 1 for the first observation taken on the 

 cruise and continuing consecutively. If num- 

 bers are omitted, make a note to that effect at 

 the bottom of the log sheet; otherwise, the 

 checker may think a data sheet or series of 

 observations is missing. 



14-58 Time. — Time is recorded in Green- 

 wich mean time (GMT). Give the hour and 

 minute at which tlie BT enters the water. 



14-59 Date.— Record the day of the 

 month only. 



14-60 Latitude and Longitude. — Give the 

 ship's position, in degrees and minutes, at the 

 time the BT enters the water. Be sure to 

 indicate whether latitude is N or S and longi- 

 tude is E or W. Where these do not change 

 on a log sheet, they may be entered once at 

 the top of the columns, as shown in figure 14-3. 

 These positions should be obtained from the 

 adjusted ship's track as given on the smooth 



H. O. 607 



143 



