72 



NA TURE 



\Nov. 25, 1875 



the two basins. While in the Atlantic it seems certain 

 that the temperature sinks gradually, though very slightly, 

 for the last thousand fathoms to the bottom, it appears 

 that in the Pacific the minimum temperature of i°7 C. is 

 reached at a depth not greater than 1,400 fathoms, and 

 that from that depth to the bottom the temperature is the 

 same. 



The soundings from Yokohama to Honolulu are re- 

 markably uniform in depth, the twenty-two soundings on 

 one line which are unaffected by the neighbourhood of 

 land giving an average of 2,858 fathoms. The nature of 

 the bottom is also very uniform ; and, according to the 

 nomenclature which we have adopted, it is in each case 

 noted on the chart as "red clay." It is usually, however, 

 somewhat greyer in colour than the typical " red clay," 

 and contains a large proportion of the tests of siliceous 

 organisms, a proportion which increases with increasing 

 depth, and a considerable proportion of pumice in dif- 

 ferent states of comminution and decomposition. The 

 clay contains scarcely a trace of carbonate of lime, 

 although the surface swarms with ooze-forming foramini- 

 fera. In some cases the trawl carne up half full of large 

 lumps of pumice, which seemed to have been drifted 

 about till they were water-logged, and to be softening and 

 becoming decomposed ; these pieces of decomposing 

 pumice were often coated and pervaded throughout with 

 oxide of manganese. Over the shale area the red cUy 

 was full of concretions, consisting mainly of peroxide of 

 manganese, round, oval, or mammillated and very irre- 

 gular, varying in size from a grain of mustard-seed to a 

 large potato. When these concretions are broken up, 

 they are found to consist of concentric layers having a 

 radiating fibrous arrangement, and usually starting from 

 a nucleus consisting of some foreign body, such as a piece 

 of pumice, a shark's tooth, or a fragment of any organism, 

 as for instance in one case a piece of a Hexactinnelid 

 sponge, of the genus Aphrocallistes, which was preserved 

 as a very beautiful fossil in the centre. The concretions 

 appear to form losse among the soft clay ; the singular 

 point is the amount of this manganese formation, and the 

 vast area which it covers. 



We were particularly successful during this cruise in 

 getting good samples of the fauna from great depths ; and 

 we found that the fauna of the North Pacific at depths of 

 from 2,000 to 3,000 fathoms, although not very abundant 

 in specieSj is by no means meagre. For each of six 

 dredgings and trawlings at depths greater than 2,000 

 fathoms, we found along with a few fishes a fair represen- 

 tation of all the larger invertebrate groups ; and in one 

 dredging, No, 253, at a depth of 3,125 fathoms, we took a 

 small sponge, a species of Cormilaria, an Actinia, an 

 annelid in a tube, and a Bryozoon. We were again struck 

 with the wonderful uniformity of the fauna at these depths ; 

 if not exactly the same species, very similar representa- 

 tives of the same genera in all parts of the world, I am 

 glad to be able to report that everything is going on in a 

 satisfactory way in the departments under my charge. 



ACOUSTIC CLOUDINESS 



WHEN the weight and number of the guns In action 

 are taken into account, the following extract from 

 " My Experiences of the War between France and 

 Germany," vol. ii. pp. 285-9, by Archibald Forbes, will 

 probably be regarded as the most extraordinary instance 

 of " acoustic cloudiness " hitherto recorded. The com- 

 plete reversal of the optical and acoustical conditions on 

 two succeeding days renders the case very perfect, I am 

 indebted for the extract to the obliging kindness of Mr. 

 James Kenward, of Birmingham. 



" The morning of the 6th presented a remarkable con- 

 trast in every respect to that of the preceding day. The 

 latter had been cold to the chilling of the marrow, and so 

 thick that nothing was to be seen half a mile away. The 



former was clear, bright, and warm as a morning in the 

 end of March. Yesterday the air was charged with sound ; 

 to-day there reigned the stillness of an Arcadia that 

 knows not war. Men looked at each other in blank 

 amazement. Had Paris, forts, big guns, bombardment, 

 and the no-bombardment on the eastern side alike been 

 spirited away ? Had the French reply shut up our pretty 

 Spandau toys in one day ? Or, on the contrary, had those 

 pieces of finished mechanism stove in the forts and 

 batteries bodily ? And if we were going up to Mont- 

 morency, should we see the white flag on the top of 

 Montmartre in token that all was over? Men were 

 reticent in expressing speculations, but at the corners of 

 the straggling lanes of Margency I heard the words 

 ' Capitulation,' ' Parlementaire,' muttered as the feld- 

 gensdarmes and the orderly-men gossiped in little groups. 

 Making the best of my way to head- quarters, I found 

 head-quarters in ignorance and suspense. Nobody could 

 interpret this strange, ghostly silence. There had come 

 from Versailles on the previous night a telegram stating that 

 the King was well pleased with the results which the day's 

 bombardment had achieved. So it was plain the silence 

 was not on our part due to coercion. ' Negotiations, 

 then ? ' I suggested to my friendly interlocutor. ' No, 

 that cannot well be,' was the reply, * since in that case we 

 should have received instant instructions to silence our 

 Maas Army batteries, and this has not been the case.' 

 ' Are they firing, then ? ' I asked, for it might be that I had 

 been struck with sudden deafness. ' No, it would seem 

 not, I can hear nothing. The silence is a puzzler, but we 

 are sure to hear all about it within a few hours.' Deter- 

 mining to anticipate by personal investigation the infor- 

 mation which was kindly promised me, I rode off to thei 

 front of Montmorency, whence there lay spread before the] 

 eye the wide panorama of the north side of Paris. Still alii 

 was silent as the grave. There was the white foreground, f 

 the ice-bound river, and the St. Denis chimneys smoking j 

 lustily according to their wont. Neither from the east norj 

 the west came there the slightest sound of firing. A^ 

 slight haze-bank hung over Le Bourget, which might have! 

 been snow, fog, or the filmy smoke of a cannonade ; but, j 

 if the latter, it must have surely been audible. There I i 

 found three mounted of^cers, and we had a little talkl 

 about the position. They inclined to the armistice-nego*j 

 tiations theory, more especially as they had not heard a I 

 single shot since morning. As we spoke, there came 3| 

 white jet of smoke out of the grey side of La BricheJ 

 No sound ; for all the noise it made it might have been atfj 

 escape of steam. But in a second or two we did hear 

 something — the close swish of the shell, and then the 

 explosion about fifty yards to the right. La Briche could 

 not resist the temptation of the group, ' No negotia- 

 tions, then, that is certain,' was the remark as we broke 

 up and went our several ways, 



" This action of La Briche rather intensified the puzzle, 

 because it seemed to knock away the only explanation, 

 I could not go to the south, but I could visit the batteries 

 about Pont Iblon, and get at the root of the matter. 



" I came on to Gonesse alone. What was my surprise 

 to find all the German batteries from Gonesse to Sevran 

 firing away vigorously ! They had been at it since eight 

 in the morning. In Gonesse I learned that the firing on 

 the south side was believed to have recommenced at the 

 same hour, and was certainly going on. Yet at Margency \ 

 and Montmorency we could not hear a sound. It was i 

 all owing to the air ; it was to-day as non-conducting of] 

 sound as it had been the reverse yesterday. Even inj 

 Gonesse we could not hear the guns that were thunder^ 

 ing, so to speak, at our elbows." 



The condition of things here so graphically described] 

 discloses a state of the atmosphere precisely similar to' 

 that existing at the South Foreland on the 3rd of July, 

 1873. There, as here, the belching of the smoke from 



