328 



SCIENCE. 



[Vol. XII. No. 308- 



SCIENCE 



A WEEKLY NEWSPAPER OF ALL THE ARTS AND SCIENCES. 



PUBLISHED BY 



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NEW YORK, Dec. 28, 1SS8. 



No. 308. 



CONTENTS: 



The McAuley Process of Bur 

 iNG Pulverized t'UEL 



Profiles of the Nicaragua ai 

 Panama Canals 



The Sprague Electric Road at 

 Boston 



Mohammedanism and Slave- 

 Trade in Africa 



Brain and Sociability. 

 Notes and News 



Editorial 



Mohammeda 



nd Slave-Trade 



n Africa 

 Advanxes in El 



328 



The Scientific Work of the 

 Johns Hopkins University... 



Stanley and Emin Pacha 



Scientific News in Washington. 

 Ojibwa Folk-Lore 



Teton Folk-Lore 



Interesting University Sta 

 Attendance upon Colleges and Sci- 

 entific Schools 



Iealth Matters. 



Baldness 



Plastering Wines 



Organic Poisons 



3ook-Reviews. 

 The Civilisation of Swede 



Heathen Times 



E.xperimental Mechanics 



Among the Publishers.. 



We PRINT at another place in this number a brief account of 

 the spread of Mohammedanism in Africa. While we may consider 

 its influence upon the heathenish tribes of Africa as detrimental, 

 we must not underestimate its vast historical importance. People 

 like the African aborigines are not roused to activity by the teach- 

 ings of Christian missionaries; the appeals of the Mohammedan 

 dervishes, which instigate their passions and arouse their warHke 

 dispositions, are more likely to raise peaceful tribes to historical 

 importance. The power of Mohammedanism to create commotions 

 of vast historical importance has been frequently shown. It shows 

 itself at present in the whole Sudan, and, notwithstanding the en- 

 deavors of all European nations, it is doubtful whether it will be 

 possible to stay its progress and to redeem Africa from the curse 

 of slavery. The existence of slavery is inseparably connected with 

 that of the Mohammedan states. The present endeavors of the 

 European powers which are directed against the East African slave- 

 trade have some chance of success, as there are no inaccessible 

 Mohammedan states in that region, and the slave-trade is kept up 

 principally by a small number of individuals. Cardinal Lavigerie, 

 to whom this movement is partly due, maintains that five hundred 

 trained soldiers marching through the German territory by way of 

 Unyanyembe to Udjidji, on Lake Tanganyika, could crush the 



slave-trade and disarm and forever disable the Arab slave-mer- 

 chants ; but slave-raids of some form or other will continue to exist 

 until means of conveying goods from the interior to the coast have 

 been found, making unnecessary the use of carriers. It seems, how- 

 ever, that the principal region of slave-trade, that of Sudan, must 

 for a long time remain inaccessible to European influence. 



THE ADVANCES IN ELECTRICITY IN 1888. 



When we contrast the present state of electric science and in- 

 dustry with their condition a year ago, we are struck with the re- 

 markable advances that have been made, especially in the latter. 

 The most important experiments bearing on the theory of electricity 

 have been those of Hertz on the propagation of electrical disturb- 

 ances, with investigations by various workers on the effect of light 

 on various electrical phenomena. Hertz has obtained electric os- 

 cillations of a very short period, — several hundred millions in a 

 second, — and he has shown that electro-magnet waves caused hy 

 them are propagated in the surrounding space, and are reflected 

 and interfere with one another as do waves of light. To those 

 who have not believed the electro-magnetic theory of light, these 

 experiments will be of great importance : for those who have be- 

 lieved the theory, they will add corroborative and strengthening; 

 evidence. Our general views of the electric current have been 

 gradually changing ; and the idea of the energy of the current 

 being transmitted through the surrounding dielectric, and entering 

 the wire at every point, is changing our methods of treating prob- 

 lems of current propagation and our conceptions as to the mechan- 

 ical reality that underlies the phenomenon. A number of experi- 

 ments on the discharge of condensers have been made, notably by 

 Professor Lodge, with a view of developing a theory of lightning, 

 and of providing the best means of guarding against lightning- 

 strokes. There grew out of Professor Lodge's experiments a 

 warm discussion before the British Association, on lightning-con- 

 ductors, in which there was shown a wide difference of opinion be- 

 tween ' theoretical ' and ' practical ' men as to the best means of 

 protection against lightning, and the interest aroused promises to be 

 the means of adding largely to our knowledge on the subject. The 

 development of the alternating system of electric lighting has 

 stimulated investigations in that direction, and a number of experi- 

 ments on self and mutual induction, on induction-coils, etc., have 

 been made. 



In the application of electricity the advance has been much more 

 striking, especially in this country. In lighting, the increase in the 

 number of lights has been steady and rapid ; and, although no 

 radical improvements nor fundamental discoveries have beenmade^ 

 yet the efficiency of all of the lighting systems has been increased,. 

 and the expense reduced. In arc-lighting there have been only 

 changes in detail of the important systems ; but the number of new 

 stations being equipped, aijd that have started in the last year,, 

 greatly exceeds the showing made in 18S7. Incandescent lighting 

 has progressed still more rapidly. The Edison Company has 

 erected central stations of large capacity — up to a maximum of 

 50,000 lamps — in New York, Philadelphia, Chicago, and other 

 cities, besides adding to the already long list of smaller stations. 

 They have increased the efficiency of their incandescent lamps, and 

 have perfected their dynamos. The returns of stations using this 

 system have been for the year most satisfactory, and it is stated in 

 some of the technical papers that a large amount of capital — no 

 less than ten million dollars — has been subscribed abroad for the 

 extension of the system. The number of electric motors that have 

 been supplied from central stations has also largely increased. The 

 Westinghouse Company has continued to distribute electricity by 

 the alternating system, and has rivalled the increase of the older 

 Edison Company. The advantages of their system for distributing 

 to scattered points, and even in cities where overhead wires are al- 

 lowed, and where the lights are not concentrated in a particular 

 neighborhood, — the lighting of stores, halls, theatres, etc., — are 

 apparent. The efficiency of their converters and lamps has been in- 

 creased, and experiments are being carried on with a view to per- 

 fecting some motor that can be used on alternating circuits. 

 Other companies are doing a great deal of business in a quiet way 

 in putting in private installations for factories, offices, etc. There has 



