INTERNATTO'J^AL ICE OBSERVATION AND ICE PATROL SERVICE. 69 



depth values are, on that account, exact only in the absence of winds 

 and currents. When the series of bottles were, by the drift, carried 

 iiway from the vertical, the values given wore maxima to which the 

 true depths approached fairly closely — more or less in proportion to 

 the vessel's leeway. 



Generally two thermometers were used, as checks on each other, 

 in securing the temperature reading for each depth. But sometimes 

 the action of one of the thermometers was obviously faulty, or for 

 other reasons only one thermometer supplied the data. In such cases 

 the temperature value is marked in the table with a dagger. Only 

 such thermometers were used as had been tested for errors — the 

 Schmidt and Vossberg thermometers at the Hydrographic Labo- 

 ratory of the International Committee for the Exploration of the Sea 

 in Copenhagen; of the Negretti and Zambra, the older at United 

 States Bureau of Standards, the newer at the National Physical 

 Laboratory in Teddington, England. The correction certificates 

 from these sources have been used to obtain the corrected tempera- 

 tures from the original readings of the reversing thermometers and 

 the auxiliary stems. These final values are subject to an error 

 lying wathin ±0.1° (C). Certain of the temperature determinations 

 were found to contain a larger error, of ±0.2° or even ±0.3°, and 

 they are indicated in the table by asterisks. Furthermore, since the 

 temperatures marked with daggers were obtained from single ther- 

 mometers, it is not possible to be as confident in their accuracy as 

 otherwise. Yet for the most part they are probably no more in error 

 than the unmarked temperatures, certainly no more than those 

 marked with asterisks. 



The standard method of titration with silver nitrate was employed 

 to determine the salinity of the water samples which were preserved 

 in citrate of magnesia bottles.^ 



In general the results, expressed in grams of total salts per 1,000 

 grams of water, are estimated to be accurate within ±0.04. But 

 in the case of values marked with asterisks the error may be as 

 great as ±0.08. 



First in the column of specifications of the nets is given the diam- 

 eter of the mouth, as ^ m. (meter). Next is stated the number of the 

 netting fabric. No. 18 specifies cloth having 166 meshes per inch; 

 No. 6, 74 meshes per inch; No. 0, 38 meshes per inch. The ^ and ^ 

 meter nets are made all of one fabric. The 1-meter nets are coarser 

 at the forward, or oval, end than at the after cones. Thus the 

 1 meter. No. 6 net has a tip of No. 6 cloth and an entrance of No. 0. 

 Similarly, the 1-meter, No. net has a tip of No. find an entrance 

 of No. 000 (23 meshes per inch). The No. and No. 000 cloths are 

 of XX, double extra heavy grade, while the No. 6 and No. 18 cloths 

 are of standard weight. 



For the horizontal towings there is recorded approximately that 

 depth, or range of depths, at which the net was towed for most of the 

 haul. But since the net remained open while being hoisted on board, 

 a small proportion of its contents were, inevitably, organisms occur- 

 ring in levels overlying the stated depths. 



In regard to the duration of the hauls, the times quoted are 

 approximate and the speed of towing was variable. Still, the catches 

 are roughly quantitatively comparable on a basis of the stated 

 durations and an average speed of 2 knots or slightly less. 



3 Titration done at Cambridge, Mass. 



