Sept. 28, 1876] 



NATURE 



491 



and that between the parallel of 30 deg. and 40 deg. N, 

 latitude, the isotherm of 60 deg. occupies a depth of 300 fathoms, 

 over an area of 1,200,000 square miles, while the average depth 

 of this isotherm between the parallels of 30 deg. and 40 deg. 

 S. latitude is 160 fathoms ; also that the isotherm of 40 deg. 

 which is at an average depth of 800 fathoms across the North 

 Atlantic, between the parallels of 30 deg. and 40 deg. N. 

 latitude, occupies only half that depth in any part of the South 

 Atlantic. This phenomenon may be explained in the following 

 manner : — The power of the sun indirectly heating the water 

 below the surface appears not to extend below 100 fathoms even 

 in the tropics, and this power decreases as the higher latitudes 

 are reached, until a position is attained where the temperature 

 is that of the freezing-point of salt water. As salt water at its 

 temperature of congelation is denser than at any higher tempera- 

 ture, its weight would cause it to sink, and it would in time, 

 did no other cause intervene, occupy the whole of the space in 

 the ocean not influenced by the sun's heat. But in considering 

 the eflect of the heat imparted to the surfaces we have also to 

 consider the effect of evaporation and precipitation. In the 

 equatorial regions evaporation is rapid, so that the surface film 

 would become cleared through increased salinity were it not for 

 the increased temperature and large precipitation, as well as to 

 its being transported by the friction of the trade winds and 

 earth's motion to the westward. This surface film, constantly 

 moving westward in the equatorial regions, meets in the Atlantic 

 with an obstructing point of the South American continent, 

 which directs it to the northward, so that the greater part of the 

 water directly heated by the sun's rays in the tropical regions is 

 forced into the North Atlantic. As the salinity of this water is 

 greater than that of the subjacent layers, and its increased tem- 

 perature only renders it less denser, directly a portion of this 

 temperature escapes in the colder regions of the temperate zone, 

 the surface film sinks and imparts heat to the water beneath. 

 Consequently, the isotherms will be found at greater depths 

 where the heated surface films are constantly descending than 

 when, owing to their being less denser than the subjacent layers, 

 they remain on the surface. 



Mr. J. Murray stated some results of his observations on board 

 the Challenger — On the Geological Distribution of Oceanic 

 Deposits. These deposits were stated to be of three classes — 

 first, those which were found all round the continents and islands 

 existing over the world, without any exception, but which varied 

 according to the places where they were found ; secondly, those 

 found at from 200 to 300 miles from the land, consisting of shell 

 and lime deposits, and covering most of the bed of the ocean ; 

 thirdly, those existing at other depths, and which were of silicious 

 character. The observations showed that a curious relation 

 existed between the nature of the deposits and the depth of the 

 water. It was also pointed out that in the neighbourhood of 

 volcanic islands, and in no other places, were found large de- 

 posits of manganese, coating the shells and other things brought 

 up from the bottom. 



Mr. Buchanan submitted a communication of observations of 

 the Challenger, bearing upon The Specific Gravity of the Surface 

 Water of the Ocean. He also explained the principles on which 

 he constructed a new deep-sea thermometer with which his ob- 

 servations were made. 



Professor Porter read a paper On some Points of Interest in the 

 Physical Conformation and Antiquities of the yordan Valley. The 

 general geological structure of the valley was, he said, of lime, 

 and of the same age as the basin of the Sea of Galilee, and its 

 surface was flat. The breadth varied from three to ten miles, 

 extending a little towards the east, and from the nature of its 

 thick alluvial covering, it was of more recent formation than of 

 the mountains, the valley having been at one time apparently a 

 lake, of which the soil was the deposit. The river Jordan as it 

 at present existed, could have had nothing to do with the forma- 

 tion of the valley itself. He recommended to the notice of men 

 of science that geological remains on the site of Sodom and 

 Gomorrah pointed to an explosion of bitumen much later than 

 the ordinary geological formation, and probably within the 

 historic period. 



Signor G. E. Cerruti read a paper On his Recent Explorations 

 in N. W. New Guinea. After several visits to the islands and part 

 of the mainland on the north, he was in 1869 sent out by Count 

 Menabrea for the purpose of making investigations preliminary 

 to the formation in New Guinea of a penal settlement. He 

 secured at the same time means for turning his expedition to 

 profit geographically. He believed that a great part of the region 

 from the Xulla Islands to New Guinea, and perhaps more to the 



north, had been subject to very important volcanic action in an 

 epoch not very far distant, and one could see the work 

 now going on — the western coast showing gradual subsidence. 

 But whatever the origin of the islands, they were now covered 

 with a vegetation which he had not found equalled in luxuriance 

 in any part of the world. He urged in strong terms the colonisa- 

 tion of New Guinea. 



This Section was brought to a premature close on Tuesday the 

 1 2th from want of an audience. The meetings were held in the 

 Queen's Rooms, at a considerable distance from the University, 

 which no doubt to a great extent accounts for the poor attendance. 



SECTION F. — Economic Science and Statistics. 



Dr. William Jack read a paper On the Results of Five Years 

 Compulsory Education. After entering into considerable details 

 as to the working of the system, he concluded that he had 

 established the following points: — I. That the need of the 

 country for compulsory education was a crying need in 1870. 

 2. That the succeis of the experiment which has now been tried 

 in Scotland, and in nearly half of "England, justifies the very 

 modest advances that have been made by the Government in the 

 bill of the present year. 3. That compulsion has been carried 

 out in one great city with perfect efficiency^ and with a very 

 trifling amount of legal process. 4. That there is no agency 

 short of compulsion which can bring Ireland on a level in popular 

 education, with her sister countries. A very interesting discus- 

 sion followed the reading of this paper. 



Mr. J. Hey wood, F. R.S., read a paper On the Memorial of 

 Eminent Scientific Gentletnen in favour of a Permanent Scientfic 

 Museum. He advocated the placing on a permanent basis an 

 institution similar to the Loan Scientific Institution now open at 

 South Kensington. 



The Rev. Dr. M 'Cann then read a paper On the Organisa- 

 tion of Origijtal Research, in which he advocated an exceedingly 

 elaborate system for carrying out the object in view. 



After some discussion in which Dr. Jack, Professor Hennessy, 

 of Dublin, and others took pa it, Mr. Hey wood submitted the 

 following resolution — " That this Section approve of the mam- 

 tenance of a scientific museum in London, containing scientific 

 apparatus, appliances, and chemical products." 



Sir George Campbell, in summing up the discussion, said he 

 should support this motion, and he also agreed^with Dr. M'Cann 

 that there should be a national system of scientific education. 



The motion was unanimously passed. 



An important discussion took place in this Section On the 

 Civilisation of South-Eastern Africa, caused by the reading of a 

 paper on the subject by Mr. Stevenson. 



SECTION G.— Mechanical Science. 



This Section met under the presidency of Mr. Charles W. 

 Merrifield, F.R.S., who in his address spoke of our shortcomings 

 in those subjects of instruction which are the necessary preludes 

 to mechanical science. He urged the importance of physical 

 science as that which had given us command over the material 

 powers of nature, and which alone could enable us to keep pace 

 with other nations in industrial competition, and to maintain the 

 health of crowded populations. With their populations, which 

 had more to fear from war and famine than from want of elbow- 

 room, political and historical knowledge in the governing class 

 was more important than exact knowledge in the administrative 

 class ; but as the population thickened, the latter assumed more 

 importance ; and while he did not think political wisdom would 

 ever lose its value, he thought it only a part of such wisdom to 

 recognise that in such communities as ours the spread of natural 

 science was of more immediate urgency than any other secondary 

 study. One of the obstacles to the spread of science and to our 

 national prosperity he took to be the undue preference given to 

 literary over natural knowledge, and in particular the sacrifice of 

 mathematics to classical study in the secondary schools. Apart 

 from the general fault of giving too low a place to mathematical 

 teaching, a great fault was our not paying sufficient attention 

 and sufficiently early attention to mechanical and geometrical 

 drawing. He concurred with a remark of Professor Fleeming 

 Jenkin that descriptive geometry was not what was wanted. 

 A much more important exercise of geometry, and one more im- 

 mediately useful, was the geometrical representation of arith- 



