3o8 



NATURE 



[July 30, 1891 



An Honorary Foreign Council, including the names of most of 

 the best known foreign hygienists, has been appointed, and also 

 an Honorary Council of the British Empire, with representatives 

 from India and the colonies. 



A Bacteriological Museum and Laboratory will be a special 

 feature in connection with the work of the second Section ; and 

 an exhibition of drawings of sanitary construction, in connection 

 with the work of the sixth Section, will be arranged in the 

 Library of the University of London, under the direction of Mr. 

 Thomas W. Cutler. 



As is usual in gatherings of this kind, a considerable number 

 of entertainments, excursions, &c., have been arranged for, 

 including an entertainment at the Guildhall, conversaziones ac 

 the Royal Colleges of Physicians and of Surgeons, and a dinner 

 axiA fete at the Crystal Palace. 



A Ladies' Committee, under the presidency of Mrs. Priestley, 

 has also been formed for the purpose of holding receptions and 

 of organizing visits to various places of interest for the benefit of 

 the ladies who may take this opportunity of visiting London. 



A daily programme will be issued, giving the titles of the 

 papers to be read, and the list of excursions, entertainments, 

 &c., for each day ; and besides this. Public Health, the journal 

 of the Society of Medical Officers of Health (under the editor- 

 ship of Mr. A. Wynter Blyth) will issue a special daily number 

 during the Congress, giving abstracts of the more important 

 papers in each Section. 



A volume of abstracts of papers will also be issued, and 

 a special hand-book for London is being prepared by 

 Messrs. Cassell and Co. in French and English ; this will 

 contain several maps and plans, and will be mainly devoted to 

 those matters which have a special interest for members of a 

 Congress of Hygiene and Demography. 



After the Congress a volume of Transactions will be pub- 

 lished, to a copy of which each member will be entitled. The 

 subscription is ^l, and the offices are at 20 Hanover Square. 



THE ORIGIN OF CERTAIN MARBLES} 

 ''\ MONGST the interesting collection of rocks brought home 

 '-^^ by Prof. Haddon from Torres Straits are some fragments 

 of wind-blown coral-sand rock from Thursday Island. They 

 have a deceptively oolitic appearance, and the majority of the 

 grains being of a red colour give a prevailing warm tint to the 

 stone, and thus render more conspicuous by contrast a number of 

 dark green, worn, and rounded crystals of augite, which are 

 scattered irregularly through it. The appearance of this hand- 

 some rock is sufficiently striking, but it gains greatly in interest 

 from its suggestive resemblance to the famous Tiree marble, 

 wherein likewise green grains of pyroxene are set in a flesh- 

 coloured matrix of altered limestone. The comparison is con- 

 firmed and enhanced by an examination of thin slices ; in the 

 recent limestone the calcareous grains are found, as so commonly 

 happens with these coral-sand rocks, to consist of rounded frag- 

 ments of calcareous Algae, and worn tests of various species of 

 Foraminifera ; mingled with these are more or less rounded 

 ■ crystals, not only of green augite, but also of olivine, felspar, and 

 a finely crystalline glassy basalt ; in the Tiree marble the green 

 grains of pyroxene (salite) show beautifully rounded outlines, and 

 are sharply separated from the surrounding matrix, into which 

 they show no tendency to pass ; crystals of felspar are also pre- 

 sent—some fairly fresh, others, and these are the majority, 

 corroded and almost entirely replaced by calcite, only the thin 

 outer skin of the felspar preserving a fresh appearance ; in some 

 few cases, fragments of felspar partially penetrated by salite are 

 met with. The calcareous matrix is finely granular, possibly 

 dolomitic, but blotched and spotted by badly defined larger 

 crystalline individuals of calcite, the outlines of which are some- 

 times obscurely rounded, so that although no trace of organic 

 structure can now be recognized, yet on the whole the appearances 

 are such as might be expected to be presented by a coral-sand 

 rock, which had suffered metamorphic changes. Macculloch, in 

 his detailed account of this rock, refers to its occurrence as an 

 irregular mass, completely surrounded by gneiss ; another white 

 limestone occurs in the island, similarly disposed. 



It is interesting to speculate on the final result of pressure 

 metamorphism, acting on volcanic islands surrounded by their 

 reefs. Thus, were the ancient granite masses of Queensland and 

 New Guinea to approach one another, moving towards the line 



' A Suggestion : by Profs. SoUas and Cole. 

 NO. I 135, VOL. 44] 



of weakness which now forms Torres Straits, we may conceive 

 that basic schists in great variety would arise from the rolling 

 out of the cores and superficial deposits of the intervening 

 volcanoes ; while the associated coral reefs would be converted 

 into irregular masses of structureless limestone, and becoming 

 involved in the surrounding schists would be irregularly dispersed 

 through them, so as to occur in unexpected and anomalous 

 positions. 



In conclusion we would call attention to an important paper, 

 read in 1876, by Mr. W. L. Green, Minister of Foreign Affairs 

 to the King of the Sandwich Islands (footnote, Journ, Roy. 

 Geol. Soc. Ireland^ vol. iv. p. 140, 1877). Inter alia, he 

 says : — 



" The Hawaiian Islands are more or less surrounded by coral 

 reefs, the island of Hawaii less so than the others, for one reason, 

 because the lava has kept pouring into the sea along most parts 

 of the coast during past centuries, and has not given the coral an 

 opportunity to form to so large an extent as in the other islands. 

 Now it is a fact that wherever the lava runs into the sea, or 

 wherever the waves have an opportunity of breaking against [it], 

 ... a large quantity of olivine sand is formed. The felspar, 

 the other material of which this lava is mainly composed, gets 

 ground up to powder and disappears — indeed, it is almost always 

 in the minutest grains to begin with ; whilst the olivine, a much 

 heavier mineral, and in grains from the size of a bean to a pea 

 downwards, forms the main component of the sand of the sea- 

 shore wherever the sea meets the 'lava, or else the olivine-sand 

 gets more or less mixed up with the coral-sand, where the two 

 classes of rock are in close proximity. A great deal of the 

 olivine-sand is of the finest possible quality ; indeed, it is often 

 so fine that although a much heavier mineral than carbonate of 

 lime, it will often, where both are washed by the waves, settle 

 on the top of the coral-sand, and I have often scraped the almost 

 pure fine olivine-sand from the top of a coral-sand beach. This 

 mixture of the two sands is common over the group, extending 

 400 miles from Hawaii to Bird Island." Again, " . . there 

 is every grade of mixture from all coral to all olivine. Very 

 often the olivine-sand rock will be found to run in streaks 

 amongst the coral-sand rock, so that in the course of time, when 

 the coral-sand rock comes to be metamorphosed into a limestone 

 or a marble, the olivine-sand rock would probably suffer the 

 change which that mineral is well known to experience — namely, 

 into serpentine." 



These views will certainly commend themselves to many of 

 those who have come to regard Eozoon as a mineral structure. 

 With the presumption in its calcareous composition of an organic 

 origin, there has always existed a suspicion that some such ex- 

 planation as this might eventually be found. It is interesting 

 to note that the streakiness which Mr. Green expressly mentions 

 as characterizing the interlamination of the olivine and coral 

 sand, is so frequently an accompaniment of " Eozoonal " and 

 serpentinous limestone. 



IS THE MARINER'S COMPASS A CHINESE 

 INVENTION? 



A WRITER in the North China Herald of Shanghai devotes 

 -^^ a learned article to detailing and discussing the facts re- 

 garding the claim of the Chinese to have invented the mariner's 

 compass. They did not learn the properties of the magnetized 

 needle from any other country. They found it out for themselves, 

 though it is impossible to point to the man by name who first 

 observed that a magnetized needle points north and south. He 

 suggests that it came about in this way. The Chinese have in 

 their country boundless tracts of ironstone, and among these no 

 small portion is magnetic. Every woman needs a needle, and 

 iron early took the place of the old stone needles, and were 

 commonly used before the time of Ch'in Shih-huang— that is, 

 more than twenty-one centuries ago. Whenever a needle hap- 

 pened to be made of m.agnetic iron, it might reveal its quality 

 by falling into a cup of water, when it happened to be attached 

 to a splinter of wood, for example. It came in some such way 

 to be known commonly that certain needles had this quality. 

 The great producing centre for magnetic iron is T'szchou, in 

 Southern Chihli. This city was very early called the City of Mercy, 

 and the magnetic stone produced there came to be known as 

 the stone of T'szchou, and so fszshih became the ordinary name 

 for a magnet. Later, the Chinese began to speak of the City 

 as the " City of the Magnet," instead of calling it the " City of 



