duced through foam-rubber cushioning of tlie thermometers during 

 periods of storage. The unfavorable laboratory conditions of vibra- 

 tion, noise, and excessive temperature were basically the same, al- 

 though salinity measurements were improved by the countermeasures 

 of building a filtered audio amplifier for the salinity bridge detector 

 circuit and introducing an additional ventilator duct near the salinity 

 bridge. New oceanographic winches employing electric drive and 

 hydraulic transmission were installed just prior to the beginning of 

 the season and eliminated many of the electrical and mechanical 

 troubles experienced previously and permitted more rapid occupation 

 of stations. 



As very little information is available in the literature regarding the 

 relationship between wdre tension with the wire at rest and with the 

 gear being hauled in, some measurements were made to determine 

 what standard operating procedures to follow. A hand dynamom- 

 eter was built so that it could be applied to the wire to measure 

 the wire tension whether the w^ire was at rest or in motion. It was 

 designed for 5/32-inch diameter wire rope with full scale deflection 

 at a wire tension of 2,500 pounds, which is the breaking strength of 

 the wire w^hen new. The dynamometer is shown in figure 12. From 

 measurements with the wire at rest and being hauled in at different 

 speeds and with different lengths of wire out it was concluded that 

 for practical purposes the relationship between tension at rest and 

 tension hauling in is linear under the conditions existing on the 

 E'vergreen and over the range of wire speeds measured (from 74 to 

 193 meters/minute) and may be expressed as 



T = [1.55 + 0.0042(8-100)] t 



where T is the tension with a wire speed of S meters per minute and 

 t is the tension with the wire at rest. Considering the protection of 

 \\\Q wire against excessive tension, protecting the winch against ex- 

 cessive loads and protection against two-blocking gear from inability 

 to stop in time after the incoming gear is sighted, recommended 

 standard operating procedure with limiting wire speeds is shown in 

 figure 13. This does not represent the operating procedure followed 

 in 1949, since its compilation depended upon measurements made with 

 at least 3,000 meters of wire out and opportunity for these measure- 

 ments did not arise until the postseason cruise. 



At 0600 on 4 April, the Evergreen departed Argentia to make a 

 current survey of the area over and immediately seaward of the 

 southwestern, southern, and eastern slopes of the Grand Banks. It 

 had been planned to begin the survey on the southwestern slope and 

 work around the Tail of the Banks and northward along the eastern 

 slope to about latitude 46° N., including in the area as great a length 

 along the margin of the Grand Banks as time permitted. While such 



50 



