POPULAR scie:nce news. 



[January, 1SS9. 



mogony of Moses. One by one, however, now in 

 this country and now in that, men began to give 

 some time to the investigation of the strata of the 

 earth, and their minds were gradually withdrawn 

 from the spiritual interpretation of the facts they 

 accumulated. But a tendency- to over-hasty gener- 

 alization still retarded their steps and much valua- 

 ble time was lost in defending the brilliant hypoth- 

 esis from the attacks of irreconcilable facts. 



In the early part of the present century attempts 

 to form "-theories of the earth" gave place to a de- 

 sire to multiply and record observations on which 

 some theory might be based in the future. F"acts in 

 immense number were collected and classified, and, 

 when a master mind had shown the significance of 

 these facts an impetus was given to the study of ge- 

 ology which has made its recent history one of con- 

 tinuous growth and development. 



Much has been done in many different countries 

 to discover the secrets of the earth's formation and 

 present condition, but it has, as it were, been done 

 independently in each. Special groups of rocks 

 have been studied in each, receiving names sug- 

 gested by the localities in which they were first ob- 

 served, or in which they were found to be most 

 largely developed, or from some accidental peculiar- 

 ities in the appearance of the beds. Strata of the 

 same geological age are therefore known in differ- 

 ent countries and sometimes in different parts of the 

 same country by totally different names. In repre- 

 .senting beds of rock on geological maps the colors 

 and signs used have depended largely on individual 

 taste and cannot be generally- understood without an 

 index. Geological surveys undertaken by central 

 organizations, the circulation of Geological Reports, 

 and the interchange of thought afforded by geolog- 

 ical societies, have in England, America, and the 

 leading countries of Europe, somewhat reduced the 

 confusion naturally arising from the multiplicity of 

 names and terms and methods of description. But 

 the want of greater conformity still has been very 

 seriously felt; of conformity between all workers in 

 every part of the globe, in order that the work of 

 each may be available for all. 



At the Buffalo Meeting of the American Associa- 

 tion for the Advancement of Science in 1876, the 

 presence of a great number of foreigners who had 

 been drawn to America by the Centennial Exhibi- 

 tion at Philadelphia, suggested the idea that the ge- 

 ologists of the various nations represented should 

 be called together to discuss some means whereby 

 more harmony could be secured in technical points 

 connected with their work. The practical outcome 

 was the nomination of a committee to make ar- 

 rangements for an IrfPernational Geological Con- 

 gress to beheld at Paris in 1878, with the special ob- 

 ject of deciding upon rules for the construction of 

 geological maps and forgeological nomenclature and 

 classification. 



This congress duly met in Paris in 1878 and 

 twenty-one countries were represented. The course 

 to be adopted in future was determined, and Inter- 

 national Committees were appointed to report to 

 the next meeting appointed for Bologna, 1881, (i) 

 on Geological nomenclature, (2) on colors and signs 

 lor geological maps, and (3) on rules of nomencla- 

 ture in Pabeontology. 



The Bologna congress was held in due course. 

 The committee reported and many resolutions were 

 passed relating to the precise meaning of various 

 geological terms. Most important of all, it was de- 

 termined that a geological map of Europe, on the 

 scale of about twenty-three and a half miles to the 

 inch, should be constructed at a cost estimated at 

 £3500, a sum which has since been contributed by 

 the various governments of Europe. 



The congress met in Berlin in 1886, having been 



postponed from 18S4. on account of the prevalence 

 of cholera in the south of Europe in that vear. The 

 principal work done in furtherance of the main ob- 

 ject of the congress was in the determination of the 

 names and extent of the divisions, and the colora- 

 tion to be adopted in the geological map of Europe. 



In September of this year the fourth meeting of 

 the congress was held in London. In point of num- 

 bers it much exceeded any of its predecessors'. Two 

 hundred eminent foreign and colonial geologists 

 were present, representing twenty-one difterent 

 countries, and the number of British geologists was 

 almost as large. The geological map of Europe; 

 the classification of the Cambrian and Silurian 

 Rocks, and of the Tertiary Strata were discussed, 

 as well as some points of nomenclature referred to 

 the Congress by the International Commission; and 

 a special sitting was devoted to a discussion on the 

 Crystalline Schists. 



The meetings were held in the rooms of the Uni- 

 versity of London, Burlington Gardens, where am- 

 ple accommodation was also found for the Council 

 and Committees, and for the exhibition by the mem- 

 bers, of maps, recent memoirs, rocks, fossils, &c. , 

 which formed a special feature of this London meet- 

 ing and led to much informal interchange of thought 

 and opinion. In this interchange one of the great- 

 est uses of the Congress is served and every oppor- 

 tunity was afforded for bringing geologists of emi- 

 nence from all parts of the world into personal com- 

 munication with each other. In the afternoon vis- 

 its were arranged to the British Museunf at Blooms- 

 bury where Mr. A. W. Franks explained the prehis- 

 toric archiEological collections; to the Museum of 

 Natural History at South Kensington; to Windsor 

 and Eton at the invitation of the professors of Eton 

 College; to the Royal Botanical Gardens at Kew; 

 and to Erith. Crayford. &lc., under the direction of 

 Mr. W. Whitaker. There were, besides, afternoon 

 "At Homes" for invited guests and evening recep- 

 tions for the whole Congress by the acting presi- 

 dent. Professor Joseph Prestwick. by F. Archibald 

 Geikie, director-general of the Geological Survey 

 of Great Britain, and b^' the president of the Geo- 

 logical Society of London. Mr. W. T. Blanford. 



Great pains had been taken by the Committee to 

 prepare for the week foUoAving tlie meeting a scheme 

 of long excursions to districts of geological interest 

 which should, as far as possible, meet the desires of 

 all members who wished to see something of the 

 strata of Britain. In order that the greatest possi- 

 ble benefit might accrue from these excursions, a 

 volume was presented to every member in which a 

 full explanation with plates and geological maps 

 was given of each of the routes proposed. The Isle 

 of Wight offered exposures of Cretaceous. Eocene 

 and Oligocene rocks; North Wales, pre-Cambrian 

 and the olden Paheozoric; East Yorkshire. Juras- 

 sic and Cretaceous; West Yorkshire. Silurian and 

 Carboniferous Limestone; Norfolk and Suffolk, 

 Pliocene and Glacial beds : and Central England. 

 Triassic. 



The general impression among the foreign mem- 

 bers was that London had given them a hospitable 

 welcome, and that if the actual work done in the 

 sessions had not advanced as fast as had been hoped, 

 the opportunities for social intercourse and personal 

 inspection of museum specimens, and the \isits to 

 rock exposures, had in no small measure promoted 

 the main object of the Congress. 



THE BROWNIAN MOVEMENT. 



TiiK following is an abstract of this interesting 

 subject, delivered before the St. Louis Club of Mi- 

 croscopists, by II. M. Whelpley. Ph. G. : 



In 1S27. an English physician aiul niicroscopist, 

 named Robert Brown, described a peculiar motion 



of certain fine powders when suspended in Ifquids. 

 Under favorable circumstances he found that the 

 smaller particles of almost any powder would oscil- 

 late in a manner suggestive of the result of vital 

 force. The doctor was not the first person to ob- 

 serve this phenomenon, but he Avrote so much about 

 it that it has since become cpiite generally known as 

 the "Brownian Movement." It has also been called 

 the Brunonian movement, pedesis, non-vital motion, 

 and molecular movement. However. Professor Don- 

 ders, of Leyden. probably, was the first to observe 

 and record the phenomenon. 



It occurs, according to references, when any of 

 the following powders are suspended in water: Car- 

 mine, Vermillion, cobalt, wood charcoal, animal 

 charcoal, indigo, gamboge, pumice stone, carbonate 

 of lead (flake white), glass; also in the small crys- 

 tals of the carbonate of lime that occur near the 

 base of the spinal nerves of a frog, the crystals from 

 the iris of certain fish: the phosphates of some of 

 the elements in urine, the fat globules in milk or 

 cream, etc. I have not examined all of the crystals 

 referred to, but in addition to the list of powders, I 

 huve experimented with prepared chalk, Prussian 

 blue, Paris green, subnitrate of bismuth, oxide of 

 zinc, precipitated phosphate of lime, oxide of mag- 

 nesiuiu, calomel and carbonate of zinc. Carmine 

 gives the most satisfactory results, although Prus- 

 sian blue and Paris green are very active when first 

 mixed with water. I found it difficult to observe the 

 movement of the fat globules in milk or cream. 



The cause of the motion is not known, and, in 

 fact, very little has been said or \yritten about it. 

 Most authors refer very briefly, if at all, to the phe- 

 nomenon. Among the proposed explanations are : 

 Currents in the liquids caused by evaporation, 

 changes of temperature, light, electricity, the efl'ect 

 produced by being confined between the slide and 

 cover glass (a very indefinite reason), etc. Each 

 one of these theories has been contradicted. Where 

 .so many good authorities difl'er it is not wise to put 

 forth any great claim, liut m\ observations lead me 

 to the opinion that perhaps the heat produced by 

 the light reflected from the mirror causes small cur- 

 rents that produce thefnotion. 



In order to observe the movement all that is nec- 

 essary is to mix the powder with about ux) times its 

 volume of water, and allow it to stand until all the 

 coarser particles have subsided. Then, with a pipette, 

 place a drop of the supernatant liquid on a slide and 

 cover it with a thin cover glass. Examine the spec- 

 imen with a one-fifth inch or higher power objective 

 and a low eye-piece. It is quite necessary that the 

 slide, cover-glass, objective and ocular all be per- 

 fectly clean. I find that the motion is not simply an 

 oscillation on one plane, but the particles move up 

 and down, as is shown by the changing of the tbcus 

 as they mo\ e. 



The motion has been very carelessly contbunded 

 by some writers with the circulation of protoplasm 

 in the cells of organic matter. One authority speaks 

 of having seen it in the threads of sarcode projecting 

 from apertures in ibramineral shells. Another con- 

 siders it to be identical with the movements of the 

 granules in saliva corpuscles. These are merely ex- 

 amples of what foolish statements find their way into 

 our standard text and reference books. Some claim 

 that the motion ceases after a short time, while one 

 man reports a mount offtake white, made six years 

 ago, in which the particles are as lively as ever. I 

 have not examined it a sulficient length ol time to 

 speak authoritatively on this point. 



It is claimed by some that those substances that 

 c:in be very finely sub-divided are the ones 

 that show llie movement most readily. This 

 is evidently only a fancy, as some of 

 the most palpable powders iire the least acti\c. 



