338 Hans Pettersson 



This nodule arrived in Goteborg broken into fragments. However, by piecing the 

 fragments together it was easy to reconstruct the nodule and decide which had been 

 its surface. The results from the measurements are set out in Table II, showing 

 maximum values (presumably on the lower side)* of 1 14 and 81 units of Ra, whereas 

 samples from the upper side contained much less radium, 64, 51 and 35 units respec- 

 tively. The content of manganese was somewhat lower than in the nodule from Station 

 13, the content of iron being much the same except for one sample taken at a depth 

 of 1 -35 mm where an unusually high value of over 50% Fe was found. Two attempts 

 to calculate the rate of radial growth from the fall-off in radium content gave a value 

 of 0-4 mm in 1,000 years in each case. 



The third nodule, taken from Station 4658, was the largest and, according to my 

 view, the most remarkable of the three, both with regard to its shape and its colour. 

 It is described by Murray and Lee (1909, p. 29): 



" The nodules from this station are as remarkable for their large size as for their constant 

 shape, which is on a definite pattern. These nodules have each two surfaces, which are, roughly 

 speaking, respectively dome-shaped and cone-shaped. Looking normally at one of the surfaces, 

 the wider portion is circular, so that there is practically an axis of symmetry passing through the 

 apex of both surfaces. The dome-shaped one is due to the aggregation of a few smoothly 

 undulating bosses or protuberances of large radius. It is very smooth and black, with a metallic 

 lustre, and has a distinctly scaly structure. The other surface is mammillated, has a dull colour 

 and is incoherent, breaking up with little exertion of the fingers. A certain amount of clay is, 

 moreover, mixed with the oxides, filling the cavities between the mammillae." 



" A section across a nodule shows it to be formed of successive concentric layers following 

 exactly in their distribution the contours of the smooth surface. The innermost layer has abso- 

 lutely the same shape as the outer one. The difference between the alternate layers is mainly 

 one of hardness. In the samples cut, it has not been possible to find what was originally the centre 

 of accretion; it probably consisted of some material which has since been transformed, or rather, 

 replaced by the oxides. 



" This particular kind of nodule does not appear to have been described before; the nearest 

 approach to it, as regards shape, is one represented in Fig. 4, Plate 3, of the ' Challenger Report 

 on Deep-Sea Deposits ' " (Murray and Lee, 1909, p. 30). 



A greater number of samples from this nodule than from the two others were sub- 

 mitted to analyses. Before sampling, the nodule was cut in two practically identical 

 parts. The appearance of the section is shown in natural size by the drawing reproduced 

 in Fig. 1, which reveals the concentric arrangement of the different layers in this 

 cauliflower-shaped nodule. Its domed surface, presumably the upper one when lying 

 on the sediment,! was smooth, whereas the lower, conical surface was scoriaceous, 

 which made the sampling of this part rather difficult. Adopting Murray's views on 

 the position of the nodule on the sediment surface, viz. that the scoriaceous, conical 

 surface was the lower one, the higher radium values are ascribed to the lower surface 



* According to a footnote given in the paper by Murray and Lee their views on the original 

 position of this nodule differed (see above). 



t Dr. Lee holds that the logical conclusion is that the cone-shaped mammillated surface is the 

 upper surface, the smooth shining one being embedded in the clay, whereas Sir John Murray takes 

 the view, from liis Challenger experience, that the smooth surface was the upper one, and points to 

 Fig. 1, Plate IX, of the " Challenger report on deep-sea deposits " as confirmation of this, the smooth 

 surface in his opinion being formed above the level of the deposit. 



