628 



NATURE 



[Oct. lo, 1878 



memory to bear testimony to the soundness of his 

 judgment. Edward Hull 



Geological Survey Office, Dublin, September 27 



ROBERT HARKNESS, F.R.S. 



ANOTHER of the captains in the phalanx of British 

 geologists has dropped from the ranks. Robert 

 Harkness died suddenly in Dublin on Saturday last. He 

 had been ailing for some time, and the disease from 

 which he suffered — an affection of the heart — had gained 

 ground so much this year that he lately felt himself com- 

 pelled to resign the chair of geology at Cork. It was the 

 expectation of his friends that, released from duties 

 which he had so long conscientiously perfonned, he 

 might yet enjoy some years of comparative health in the 

 quiet retirement of his Cumberland home, to which he 

 used to return with such pleasure every summer. But 

 this was not to be. He has fallen just as he had himself 

 brought the public labours of his life to a close. 



It is now some five-and-thirty years since the name of 

 this able geologist first appeared as a writer on his 

 favourite science. During this long period he had 

 explored, on foot, the geology of large districts in 

 the north of England, in Scotland, and in various parts 

 of Ireland. The reports of the British Association 

 and the Quarterly J otirual of the Geological Society bear 

 witness to his industry and to the painstaking minuteness 

 of his method of investigation. To him we owe our 

 earliest exact information regarding the correlatives of 

 the reptiliferous sandstones of Dumfriesshire and Cum- 

 berland. It was his patient labours continued year after 

 year over ground most difficult to unravel, that led the 

 way to the working out of the structure of the silurian 

 uplands of the south of Scotland. To his research, too, 

 is due the identification of the metamorphic rooks of 

 the north-west of Ireland with those of the west of 

 Scotland. To the elucidation of every one of the paleo- 

 zoic systems of deposits he contributed something of 

 value. 



But important as was his scientific work, it had not a 

 wider and more hearty recognition among his brother 

 geologists than his own admirable qualities of head and 

 heart. Who that has been privileged with his friendship 

 will not cherish the memory of his earnestness over even 

 the driest of details, his quiet enthusiasm, his generous 

 admiration for the work of others, his unfailing cheerful- 

 ness ? Who will forget that beaming ruddy face, never 

 absent from the platform of Section C at the British As- 

 sociation meetings, always ready to rise among the 

 speakers there and to reappear at the festive gatherings 

 in the evening ? There have been men who have graven 

 their names more deeply on the registers of scientific 

 thought and progress, but there have been few whose 

 sunny nature has more endeared them in the recollection 

 of their friends than Robert Harkness. A. G. 



MANGANESE NODULES IN LOCH JFYNE 



ON September 21, this year, I anchored the steam 

 yacht Mallard near the mouth of Loch Fyne, in 

 104 fathoms, for the purpose of making physical and 

 chemical observations on the water of this, the deepest 

 part of the Firth of Clyde. W^hen the anchor was got up 

 a large mass of clay and shells was found sticking to one 

 of the flukes. It was gently dried, and on examining it I 

 observed a number of nodular concretions, which, on 

 being freed from the surrounding clay, presented a finely 

 mammillated black surface, were easily cut with a knife, 

 giving a brownish-black powder, which liberated chlorine 

 from strong hydrochloric acid, and possessed all the 

 properties of peroxide of manganese ; in short, they 

 W'ere identical with the manganese nodules which we 

 found in the Challenger to form so important a constituent 

 of the sea-bottom in the greatest depths. 



One half of the dried mud was carefully broken up 

 and searched through, the nodules being collected by 

 themselves and also the shells. It was thus separated 

 into three portions, which were weighed, with the fol- 

 lowing results: — 



Manganese nodules 



Shells 



Sandy clay 



Total ... 



1 42 '7 grammes. 



3S"o „ 

 289*0 ,, 



30 per cent. 



7-5 .. .■ 

 62-5 „ 



4667 



The manganese nodules, therefore, made up thirty per 

 cent, of the weight of the mud. Compared with those fre- 

 quently met with on board the Challettger, the nodules were 

 small. In the sample examined there were eighty-three 

 nodules weighing 1427 grammes, hence the average weight 

 was 17 grammes. Their volume was found to be 58 c.c, 

 so that the average volume was 07 c.c, and the specific 

 gravity 2*46. Their form was roughly spherical, the 

 largest, which was somewhat elongated, measured 

 13X9X6 millimetres, the average diameter of them 

 all being 1 1 '4 millimetres. 



Of the eighty-three nodules so obtained I have split 

 twenty-two. When subjected to this treatment they are 

 found to differ in constitution from the majority of those 

 obtained on board the Challettger. Although they had 

 not been exposed to any heat they were hard and sandy 

 to the knife, and when treated with strong hydrochloric 

 acid, they left a large amount of mineral (chiefly quartz) 

 sand. This difference, however, is explained by the 

 different kind of bottom from which they were obtained. 

 In dissolving up nodules which had come from "red 

 clay" in 2,500 or 3,000 fathoms I always found the same 

 mineral sand left as on treating the clay in the same way. 

 But the amount of sand was always quite insignificant, 

 as compared with the clay ; hence the nodules were easily 

 cut with the knife. They, however, got harder on 

 keeping. In Loch Fyne the bulk of the mud consists of 

 quartz sand, giving the nodules the appearance of sand- 

 stone, whose binding material is made up to a great extent 

 of peroxide of manganese, and hence the gritty feeling 

 to the edge of the knife. 



Where a hard nucleus has been found it has always 

 been a piece of rock from the neighbouring shore, but in 

 most instances (in sixteen out of twenty-two examined) 

 the ordinary arrangement has been reversed, the nodule 

 consisting of a soft rich nucleus of peroxide of man- 

 ganese, surrounded by a black sandy rind, the whole 

 enveloped in the characteristically mammillated black 

 skin. 



I hope very shortly to be able to report more fully on 

 them ; in the meantime, I have only been able to verify 

 their nature by finding abundance of a higher oxide of 

 manganese, easily recognisable quantities of cobalt, and 

 the presence of water, which, on being expelled by heat, 

 has an alkaline reaction and an empyreumatic odour, 

 properties in which they agree with those which I had 

 occasion to test on board the Challettger. 



Their position in the mud, with dead shells above, 

 below, and on all sides of them, will, when carefully 

 studied, no doubt throw much light on their age and 

 method of formation. I have observed two nodules 

 firmly attached to the interior of shells, one having 

 evidently been directed in its growth by the shape of the 

 shell. 



In endeavouring to procure a further supply I dropped 

 anchor in about the same depth, but about a hundred 

 yards further down the loch, and I obtained aboat the 

 same amount of mud, but it contained very much more 

 shell and no nodules. Also in Kilbrennan Sound, between 

 Arran and Cantyre, in a depth of eighty-five fathoms, 

 there was much shell and pebble, but no nodules. So 

 far, therefore, this occurrence appears to be very local. 



J, Y. Buchanan 



