Figure 33.— Board used to calibrate T.S-Flowmeters 

 (one meter attached). The board is balsa wood, covered 

 with fiber glass to make it waterproof, 4 ft long, 15 in- 

 ches wide X 2-1/2 inches thick (151.9 X 38 X 6.4 cm). 



Set II — to determine the volume of plank- 

 ton collected per 1,000 m^ of water 

 strained. 

 Set III — the station data and plankton vol- 

 umes for publication. 

 Set IV — to adjust SHF to percent of sample 

 sorted — no longer done — see note 

 following description of Set IV 

 below. 

 In addition, if an improper meter reading was 

 obtained or was missing for any tow, a scatter 

 diagram and regression line (Fig. 38) had to 

 be plotted and calculated for all meter readings 

 (ordinate) against all average tangents (abscis- 

 sa) in order to obtain an estimate of a meter 

 "reading" to apply to that tow (see parenthe- 

 sized data for station 60.70 in Figure 37). 



Each set duplicated the cruise number, the 

 ship, the dates of the cruise — start to end, meter 

 number (s) and net number (s). 



On Set 1, 14 columns are used of which the last 

 is the SHF. The column headings are as fol- 

 lows: 



1. Station number — from tow data sheet. 



2. Order occupied — from tow data sheet. 



3. Total time of tow in minutes and seconds — 

 from tow data sheet. 



4. Total time in seconds — derived from 3. 



5. Current meter revolutions, difference in 

 final and initial reading — from tow data 

 sheet. 



6. Revolutions per second current meter, from 

 5, divided by time in seconds. 



Figure 34. — Brass frame under calibration board (see 

 Fig. 33) on which to hang flowmeters. Only three meters 

 are calibrated at one time, the hangers nearest the board 

 are not used; meter readings were found to be erratic 

 because of the turbulence in that area. The brass frame 

 is 8 inches X 14 inches (20.3 X 35.5 cm) made of four 

 pieces of brass welded at their ends. The brass material 

 is 3/16 inch X 2 inches (5 X 51 mm). The brass an- 

 gles on which to hang the meters are cut from 1/8-inch 

 (3 mm) stock, 1-1/4 inches (32 mm) each side, 3 inches 

 (72 mm) long. Holes are bored to conform to distance 

 on centers of holes in meter lugs. Nuts are welded in 

 position to take bolts that slip fit through meter lugs. 

 Meters just hang on the bolts. 



7. Average tangent — derived from tangents 

 of all angles taken during tow. 



8. Calibration factor = meters per revolution, 

 the p in formula above — taken from cali- 

 bration curve (Fig. 36). 



9. Calibration factor X areal cross section 

 of net = a constant which, when multiplied 

 by R (total revolutions/haul) gives 



10. Volume of water strained = Col 5 x Col 9 



11. Cosine of average tangent from Col 7 



12. Wire out = total wire out before net is 

 hauled in 



Col 13 X 10 



13. STD haul factor = 



Col 10 



33 



