2 34 



NA TURE 



[July 7, 1904 



nervous symptoms; and (3) those which run a chronic 

 course and end fatally between the sixth and twelfth days 

 after poisoning. In these, histological examination shows 

 a well marked primary degeneration of the cells of the 

 central nervous system, and to this the fatal issue is due. 



The venom of the krait was found to be much less toxic 

 than that of the cobra or of the daboia, and, unlike the 

 former, has only a slightly destructive action on the red 

 blood corpuscles. It, however, markedly increases blood 

 coagulability, and may cause extensive intravascular clotting. 

 Cobra and tiger snake anti-sera possess no neutralising' 

 action for the krait venom. The use of anti-sera, the only 

 eflicient antidotes for snake bites, must, therefore, un- 

 fortunately be limited, for it is necessary to have an anti- 

 serum for the venom of every species. R. T. Hewlett. 



CURRENTS AROUND THE COASTS OF 

 NEWFOUNDLAND.' 

 TN the course of the investigations described by Dr. Bell 

 Dawson, a number of points were met with which are 

 of general interest, as they probably characterise the 

 currents on the margin of any large or oceanic area under 

 similar conditions. 



The currents in the above regions were examined last 

 season from May to September, under the personal super- 

 vision of Dr. Dawson, the engineer in charge of the Tidal 

 and Current Survey. Special attention was given to the 

 question of indraught into the larger bays on the south 

 coast, and to the behaviour of the Polar current which 

 follows the eastern coast. For this work, the D. G. S. 

 Gulnare was equipped with appliances for deep sea 

 anchorage, and apparatus of a modern type, in some ways 

 specially devised for the purpose. At anchorages carefully 

 chosen, which were made in all depths up to 100 fathoms, 

 the speed of the currents was measured, and the direction 

 noted every half hour, day and night. The observations 

 also included the under-current, the density and tempera- 

 ture of the water, the mileage and direction of the wind, 

 and a continuous record of the tide on a self-registering 

 gauge placed in a harbour in the region, for comparison 

 with the set of the current. 



The behaviour of these currents is very varied, and they 

 were found to be so weak as to be readily influenced by 

 the wind ; but by a systematic reduction of the results. Dr. 

 Dawson has prepared a report which describes the currents 

 as concisely as possible, while avoiding technicalities. The 

 report is divided into two parts ; the first deals with the 

 currents met with on the steamship route, which follows 

 the south coast for 180 miles, and the question of indraught 

 into the larger bays ; and the second part describes the 

 character of the Polar current on the east coast, and its 

 possible change of direction when disturbed. The report is 

 illustrated by nine diagrams and maps, which represent the 

 results graphically. From this report, the following de- 

 scriptions and e.xplanations are culled, which are of general 

 interest from a hydrographic point of view. References to 

 the local geography are omitted as far as possible, as they 

 might be inconvenient to follow without the map which 

 accompanies the report. 



Nature of the Cur rents. —J he currents were almost in- 

 variably less than one knot. As a rule, they veered widely 

 and were irregular in direction ; and with so low a speed 

 they were readily influenced by the wind. There were 

 three elements to distinguish :— (1) Any general tendency 

 to set in one direction more than in others. (2) Any tidal 

 influence, which might show itself either as a marked 

 change in the direction of the set, or as a period in which 

 a variation in velocity would recur. (3) The influence of 

 the wind in disturbing the usual behaviour of the current. 

 From the observation, the effect of any storms which occur 

 during the summer season seldom extends to a greater 

 depth than 5 or 10 fathoms ; and it was therefore found 

 that the behaviour of the under-current at 15 to 30 fathoms 

 afforded a most valuable indication of the normal character 

 of the current. In these currents, the tidal element is 

 almost invariably present in some form, more or less 



I "The Currents on the South-< 

 Investigations of the Tidal and Current S' 

 Dr. \V. Bell Daw*on. 



n Coasts of Newfoundland. From 

 the Season of 1903." By 



NO. 1810, VOL. 70I 



distinct ; and this is almost always combined with a tendency 

 to make on the whole in some one direction. It is not 

 therefore possible to maintain an arbitrary distinction 

 between '* constant currents " and " tidal streams " ; but 

 the only natural distinction is to use the term current for 

 all horizontal movements of the water, and tide for the 

 vertical movement from high to low water. 



The following features in these currents will be interest- 

 ing for comparison with the behaviour of currents else- 

 where, on the open coast of the ocean : — (i) When more thanr 

 five iniles froiTi shore, there are no currents at any time 

 throughout the season which exceed one knot in 

 any direction. The only exception to this is the Polar 

 current, in which a maximum speed of 1-15 knots was 

 observed. (2) On the south coast, when within four or 

 five miles of the shore, the current is chiefly governed by 

 the tide, and sets in the two opposite directions alternately! 

 but the farther out the point of observation, the greater the 

 tendency for the direction of the current to veer completely 

 around the compass. (3) The Polar current sets very con- 

 stantly to the south-west, for a width of thirty or forty 

 miles off the eastern coast. During times of disturbance, iti 

 may set south-eastward, or even be reversed, on the surface. 

 When such disturbance occurs, it is usually for part of a 

 day immediately before a gale comes on. 



In the Polar current the influence of the tide was dis- 

 tinctly marked by a fluctuation in velocity, the current 

 being 24 per cent, stronger during flood tide on the average. 

 The under-current had the same general direction as the 

 surface current. It set constantly to the south-westward, 

 even at times when the current on the surface was most 

 disturbed by the wind, judging from numerous observations 

 at 40 fathoms, or about one-half the total depth of the 

 water. The fluctuation in velocity with the tide was even 

 more marked in the under-current than en the surface. 

 During the flood tide, the strength from 15 to 40 fathoms- 

 was unusually constant, and at 40 fathoms it was always, 

 as strong and often stronger than on the surface. During 

 the ebb tide it slacked below, as it did on the surface, and 

 was usually weaker at the greater depths. When slackest, 

 at about half-ebb, it fell below one-fourth of its greatest 

 strength during flood tide, but even then the movement 

 was distinctly felt to a depth of 60 and 75 fathoms. 



Off the south shore, at an anchorage at an offing of 

 seventeen miles, the behaviour of the current was very 

 variable. During a period of nine days in June, when 158 

 hours of continuous observations v^'ere secured, a variety of 

 weather conditions obtained, although the wind did not ever 

 exceed twenty-one miles an hour. To understand the nature 

 of the current, careful comparisons with the tides and winds 

 are undoubtedly required ; but the continuity of observ- 

 ations, taken every half hour day and night, affords a good 

 basis for the comparison, and with an anemometer on 

 board, the wind observations are much better obtained thare 

 by comparison with an observatory on shore. 



The most evident change in the behaviour of the current 

 is that sometimes the direction veers completely round the 

 compass, and at other times it veers backwards and for- 

 wards between limiting directions. This change is 

 evidently due to the variation in the amount of tidal in- 

 fluence with the springs and neaps. The veer completely 

 around the compass occurs at neap tides, this being well 

 marked at the moon's quarters on two different occasions. 

 The veer is then continuously to the right, and the period 

 in which a complete revolution occurs is just about sixteen 

 hours. This period is quite definite, as deduced from six 

 complete revolutions which were observed. It appears to 

 result from a combination of the tidal period with a general 

 movement of the water to the westward. This appears to 

 be the only possible explanation, in accordance with the 

 principles of rotary inovement. This sixteen-hour period 

 has been met with at other stations during the season, as 

 well as in other regions in former years. .'\t other times 

 in the month, when the tidal influence is stronger, the 

 current veers to the right and left through a range which 

 varies from eight points to half a circumference. The 

 complete period in which it veers and backs is from ten 

 to fourteen hours. It is not impossible that this veer 

 would be found to correspond with the tidal period if an 

 average were taken which would be sufificiently long to 

 eliminate other disturbing causes. On the other hand, at 



