98 



NA TURE 



[December 4, 1902 



refractometer and an apparatus for measuring electrical 

 resistance having been experimented with. Both gave 

 fair results, but were troublesome and consequently not 

 much used. The electrical method required the use of a 

 standard solution of potassium chloride the resistance of 

 which was balanced against that of the sample by means 

 of a slide-wire Wheatstone's bridge, a telephone being 

 used instead of a galvanometer. In the long run, the 

 indications of the stem-reading hydrometers had to be 

 relied on for the tables of specific gravity and salinity 

 published in the memoir. 



Samples of sea-water were brought back for chemical 

 analysis, but they were not numerous enough to enable 

 any definite conclusions to be drawn. So far as they 

 went, they showed great similarity between the chemical 

 composition of the salts in Arctic Sea water and in 

 average ocean water, the freezing of the surface appear- 

 ing to exercise very little selective action on the dissolved 

 salts. 



The observations of temperature and density are printed 

 in full with critical remarks, and the data are utilised to 

 throw light on the circulation of the water in the North 

 Polar Basin, the results of other expeditions being con- 

 sidered simultaneously, so far as they affect the region 

 under discussion. Dr. Nansen endeavours to arrive at 

 the circulation of water in the sea by calculating the 

 density in situ and representing this on maps and sec- 

 tions by isopyknals, which bear the same relation to the 

 circulation of the sea that isobars do to the circulation of 

 the air, and by isosteres or lines of equal specific volume. 

 The flow of water is deviated from the direction of the 

 density gradient, both for horizontal and vertical move- 

 ment, by the rotation of the earth, and the amount of 

 this deviation being calculated', it is possible to estimate 

 the circulatory force of the sea due to differences of 

 density alone, supposing that there was no wind. But 

 the wind, acting on the surface water or even on the ice, 

 probably has a greater influence on the movement of the 

 water than the isopyknal gradient ; hence a large part of 

 the discussion is occupied by the consideration of the 

 wind-drift and its rotational deviation. It is quite im- 

 possible in the limited space of a review to enter criti- 

 cally into the methods by which Dr. Nansen arrives at 

 his conclusions ; indeed, the only criticism we are pre- 

 pared to make is that he has perhaps given too much 

 detail, erring towards diffuseness rather than towards 

 conciseness. However, we can give no more concise 

 statement of the general conclusion as to the Arctic Sea 

 than in Dr. Nansen's own words : — 



" We have thus, in our discussion of the distribution of 

 salinity and temperature in the North Polar Basin, 

 arrived at the conclusion that there are at least four 

 systems of currents in a vertical section from the surface 

 to the bottom, along the route of the Fram, viz., 



"(1) A surface current of water with low salinity (from 

 about 29 per mille to 32 per mille), perhaps 20m. or 30m. 

 deep, running towards the north-west and west ; 



" (2) An underlying, slow current of water with a 

 lighter salinity and a very low temperature, running in a 

 different direction, and consisting of surface water from 

 other parts of the Polar Sea. The absolute minimum of 

 temperature is situated in this current, at about 50m. or 

 60m. ; 



"(3) A current of relatively warm water with salinities 

 of from 35'i per mille to 353 per mille, coming from the 



NO. 1727, VOL. 67] 



Gulf Stream west of Spitzbergen, and running towards 

 the east at depths below 250m., the maximum of tem- 

 perature being situated in the water of this current at 

 depths of from 350m. to 450m. ; and 



"(4) An extremely slow current of colder water, filling 

 the deepest part of the basin between 900m. or 1000m. 

 and the bottom. This water is the heaviest water of 

 the preceding current, which has been cooled down and 

 has sunk towards the bottom ; it has a salinity of about 

 35'2g per mille. It is possible that this water forms to 

 some extent a spiral current under the preceding cur- 

 rent, running in a similar direction." 



The relation between the water of the North Polar 

 Basin and that of the Norwegian Sea requires additional 

 observations before it can be fully explained, and at 

 every step of the discussion new questions are raised 

 which future investigations must settle. 



The fresh surface layer of water in the Arctic Sea is 

 attributed by Dr. Nansen mainly to the inflow from the 

 great rivers of Siberia. In the mass of very slightly : 

 warmer water filling the vast hollow of the central Arctic 

 Sea below the zone of maximum temperature, there is un- 

 undoubtedly a small but distinct rise of temperature 

 towards the bottom, and this is attributed to the influence 

 of the internal heat of the earth. 



We feel that it has been possible to give only an , 

 inadequate idea of the value and originality of this great 

 contribution to oceanography, and we have laid stress , 

 rather on the methods than the results, because it is by 

 the experience gained in arriving at these methods that 

 Dr. Nansen, as Director of the International Marine , 

 Laboratory, will be able to make the physical work of 

 the International Council for the Study of the Sea fuller 

 and more accurate than any similar oceanographical 

 investigation that has gone before it. 



H. R. M. 



ANIMAL HISTOLOGY. 

 Lehrbuch tier vergleichenden Histologic der Tiere. By 



Dr. Karl Camillo Schneider. Pp. xiv + 988. (Jena: 



Gustav Fischer, 1902.) Price 24 marks. 

 Al 7"E have only one serious fault to find with this book 

 and it reflects no discredit on the author. That any 

 book should be issued to the public in such a form that 1 

 the mere operation of cutting the leaves — to say nothing 

 of perusing the pages — involves its falling to pieces can ' 

 only be characterised as a grave fault, although it is 

 common in scientific books which are " made in 

 Germany." Another fault usual in books hailing from 

 the same quarter, and against which we have frequently 

 protested, is absent in this one, for it contains an index, - 

 although not a very complete or well-arranged index. 

 For example, we find " mehrreihiges Epithel," ; 

 "mehrschichtiges Epithel," indexed, not with "Epithel" 

 the substantive, but in the alphabetical situation of the 

 adjective, where no one would think of looking for them. 

 The art and science of index making has not, it must be' 

 confessed, up to the present made much progress in 

 Germany, a fact the more remarkable since it is the 

 country which beyond all others is a producer of books 

 imperatively demanding efficient indices. 



For the work itself as a text-book of comparative 

 histology we have nothing but praise. The letterpress 



