112 



NATURE 



\Dec. 7, 1871 



We have received the first number of "The German Quarterly 

 Magazine ; a Series of Popular Essays on Science, History, and 

 Art." The plan of the publication is to give in English such 

 essays, selected from the " Sammlung gemeinverstandlicher 

 wissenschafilicher Vortrage," edited by Profs. Virchowand Franz 

 von Holtzendorff, as are likely to interest the English reading 

 public, and also original contributions ; the numbers presenting 

 alternately selections from the departments of Science, History, 

 and Art. The present number contains three papers : — " The 

 Cranial Aftinities of Man and the Ape," by R. Virchovv ; " Sight 

 and the Visual Organs," by A. von Graefe ; and "The Circu- 

 lation of the Waters on the Surface of the Earth," by H. W. 

 Dove ; all papers of great interest and importance, but loaing 

 something to the English reader from the German phraseology 

 in which the translations are clothed. They are illustrated by 

 good vroodcuts, and the subscription to the magazine is loj. per 

 an num. • 



Messrs. Longman & Co. are about to publish a volume by 

 Mr. Serjeant Cox, entitled " Spiritualism answered by Science," 

 in which he will detail the arguments that satisfied himself and 

 the other scientific investigators that the phenomena of alleged 

 " .Spiritualism " are purely physical, and in no manner associated 

 Vfith spirits of the dead. 



Dr. Bessels, the director of the scientific corps of Captain 

 Hall's steamer Polaris, in a letter addressed to the president of the 

 American National Aca.lemy of Sciences, dated Godaven, August 

 16, states that he had already made some important observations 

 in regard to the physics of the northern seas, such as a peculiar 

 coloration of the water and an unexpectedly high specific gravity, 

 the maximum density noticed being i 02S. His experiences 

 with his colleagues, iSIr. Bryan, the astronomer, and Mr. Meyer, 

 the meteorologist, have been very satisfactory ; the former gentle- 

 man having made a number of successful azimuth observations, 

 and the latter approving himself an excellent mathematician and 

 an accomplished observer, and an honour to the Signal Service, 

 from which he was detailed for duty with Cap'ain Hall. 



The recently published report of Commissioner R. W. 

 Raymond upon statistics of mines and mining in the states and 

 territories west of the Rocky Mountains for the year 1870, forms 

 a stout volume of nearly 600 pages, illustrated by a number of 

 plates and sections, embjdying the result of a laborious personal 

 examination, and that of several assistants. The report contains 

 a detailed account of the present condition of the mining in 

 dustry in California, Nevada, Oregon, Idaho, Montana, Utah, 

 Arizona, New Mexico, Colorado, and Wyoming, together with 

 interesting statements in regard to improved metallurgical pro- 

 cesses, such as especially relate to the treatment of auriferous 

 ores, the chlorination and smelting of silver ores, &c. There are 

 also chapters on narrovv-guage railways and their adaptation to 

 mining regions, the mining law, the geographical distribution of 

 mining districts, the origin of gold ingots and gold dust, and the 

 bullion product. The Commisioner congratulates the country 

 upon an increased prosperity in the mining industry, a> seen not 

 only in an augmented bullion product, but an improved lone in 

 the business itself, and relief from more or less of the irritating 

 and burdensome questions that have hitherto been connected 

 with the mining interest. Although the excitements which so 

 frequently carry off the miners and settlers of one region into a 

 new locality have been comparatively rare, yet there h.ave been a 

 few of special note. Among ihtse mentioned by Mr. Raymond 

 are those caused by the discovery of gold in Southern California, 

 near San Diego ; the discovery of silver in the Burro Mountains, 

 and the rumours of rich plactrs on Peace River, lar mto the 

 interior of British Columbia ; the bars ot Snake River ; several 

 localities in Nevada, and others in Utah ; the silver mines in the 

 Caribou district of Colorado, &c. 



COLDING ON THE LAWS OF CURRENTS 

 IN ORDINARY CONDUITS AND IN THE 

 SEA 



\n. 



T ET us now direct our attention to the polar currents, and 

 especially to that one which from Spilzbergen proceeds to the 

 south-west along the coast of Greenland as far as Cape Farewell. 

 It will be seen that this current has received an impulse from the 

 force of rotation, and rises about one foot towards the west coast 

 of Greenland, an effect which however ceases as soon as it has 

 passed the southern point of that countiy. As soon as the 

 resistance which compelled the current to follow the line of the 

 coast in proceeding to the south-west disappears, it can no longer 

 continue in the same course, but takes a westerly direction towards 

 Labrador, partly in consequence of the rotation of the earth, 

 partly because the level of the current is then higher than that of 

 the waters of Davis Strait. After having adv,anced a little into 

 the slr.ait, the polar current encounters the currents coming from 

 the north by Baffin's Bay, and joins them in their progress to the 

 south-east along the coast of Labrador, towrrds which it slopes 

 in virtue of the rotation of the earth. Daring this passage, aud 

 until its arrival in the neighbourhood of Newfoundland, this • 

 current is stemmed by the force of rotation, and ought, conse- 

 quently, to present a slope all along Davis Strait and the east 

 coast of Newfoundland as far as the Gulf Stream. During its 

 course southwards along this course, the polar current is elevated 

 towards the land by the earth's rotation ; but as soon as it has 

 passed Cape Race, this resistance suddenly disappears, and the 

 same phenomenon is i-eproduced as at Cape Farewell. The 

 current bends suddenly to the south-west, and follows the coast 

 as far as Florida, while its breadth and the volume of its water 

 continue to diminish. 



From Newfoundland to Florida, a distance of about 500 miles, 

 the Gulf Stream and the polar current flow constantly side by 

 side, under the impidse of the earth's rotation, which raises the 

 polar current towards the land and compels it to follow all the 

 ins and outs of the coast. But what force is it that impels the 

 Gulf Stream, which flows freely in the ocean, to keep by the 

 side of the polar current in all its windings, instead of taking 

 the more easterly direction, which the rotation of the earth tends 

 to give it? It is, of course, gravity, to wit, the force resulting 

 from the slope which the Gulf Stream presents from right to left 

 perpendicular to its direction throughout its entire breadth, a 

 slope which is r2 feet from the point where the current de- 

 bouches into the Atlantic to New York, and about one foot from 

 New York to the place where, after having approached the 

 shores of Europe, it separates into two branches. And if it be 

 asked why the Gulf Stream has this slope ; the reason evidently 

 is that the water of the polar current has a specific gravity greater 

 than the water of the -Vtiantic, and ou^ht consequently to have 

 a lower level thur that of the latter sea, since the water beneath 

 is in equilibrium. That this is the real state of the matter is 

 fully confirmed by the researches made in recent years in the 

 Gulf Stream at the instigation of the American Government, 

 and which leave no room to doubt that this current has not kept 

 its place on account of the difference of density which exists 

 between the waters of the polar current and those of the Atlantic. 

 Under these circumstances it is easy to see that the Gulf Stream 

 ought to follow all the sinuosities of the polar current as far as 

 Newfiiundlind. 



But while the Gulf Stream ought thus to be considered as pre- 

 senting a uniform slope from the Atlantic towards the polar 

 current, the researches underiaken by the American Government 

 prove that the bottom of the Gulf Stream could be in equilibrium 

 only if that current had an inclination directed away from the 

 polar current towards the Atlantic, such that its maximum level 

 would be nearly one-third of the distance from the polar current. 

 Under the actual conditions, then, there is no equiltbrium. The 

 waters of the polar current exercise upon the Gulf Stream a 

 prfssure which increases with the depth, and causes a continual 

 afllux of cold water, especially in its lower depth. In propor- 

 tion ns these cold waters penetrate into the Gulf Stream, it com- 

 municates to them its heat and its motion, and in proportion as 

 it is raised under the influence of the pressure of the polar cur- 

 rent driving away the water which it displaces, its breadth 

 ought to go on increasing. But in order that the breadth 

 of the Gulf Stream may increase, it is necessary that its level 

 in the centre of the current be elevated above that which cor- 

 responds to the equilibrium of the surface, so that the force of 



