ELEOTEIOITY. 



239 



Tantah for an approaching fair. At Tantah 

 he saw between five and six hundred, but be- 

 lieves the total number there on sale to have 

 been about two thousand. Having made these 

 discoveries, he informed the mudir or governor 

 of the province, who undertook to seize all the 

 slaves in the night and have them freed. He 

 only partially fulfilled his promise, and Mr. 

 Reade tells Lord Stanley that the governor 

 was ordered to desist from the work of eman- 

 cipation by a superior functionary, the Inspec- 

 tor-General of Provinces. 



Representations made by Mr. Reade to Sherif 

 Pacha were met by an evasive reply. Mr. 

 Reade had afterward an interview with the 

 minister, and convinced him that the charge 

 against Europeans of complicity in the slave- 

 trade was untrue. 



The Pacha then complained that European Chris- 

 tians in Upper Egypt were largely engaged in the 

 slave-trade, but I believe I very soon satisfied him 

 that such was not the case. The unsatisfactory na- 

 ture of Sherif Pacha's reply to my representations 

 with regard to the slave markets at Tantah and Cairo 

 will prove to your lordship, better than any thing I 

 can state from my own experience, that no reliance 

 whatever can be placed in the antislavery protesta- 

 tions of this government. 



The Blue Book contains further communica- 

 tions, of great interest as to the slave-trade car- 

 ried on in Upper Egypt, from M. Saulter, a 

 German missionary at Khartoum, and from the 

 Prussian consular agent and the Austrian vice- 

 consul at Khartoum. 



ELECTRICITY. Submerged Uninsulated 

 Cables. Mr. H. Wilde, of England, the inventor 

 of the powerful magneto - electric machine 

 which bears his name, has been making experi- 

 ments to ascertain with what degree of facility 

 electric signals may be transmitted through 

 metallic cables submerged, without an insulat- 

 ing envelope. The principal electro-motors 

 employed by him were three magneto-electric 

 machines of different degrees of power, a 

 Grove's battery, and a Daniell's battery. The 

 test of the magnitude of the current adopted 

 by Mr. Wilde in every case was, the melting 

 of a given quantity of wire, because he had not 

 been able to discover any other method which 

 could at all compare with that in expressing 

 easily, and without ambiguity, the associated 

 properties of quantity and intensity, especially 

 when dealing with currents of such magni- 

 tude as those evolved from the five and ten 

 inch magneto-electric machines. The building 

 which contained the various electro-motors 

 was situated about 100 feet from the edge of 

 the basin of a navigable canal in which most 

 of the experiments were made. Connection 

 between the electro-motors and electrodes and 

 other conductors submerged in the canal was 

 effected by means of two lengths of copper- 

 wire rope, each 140 feet long and nearly half 

 an inch thick. These wire-rope connections 

 consisted of seven thick copper wires twisted 

 together, and were supported through the air, 

 and insulated from one another, by means of a 



pole fixed upon the bank of the canal. The 

 conductors submerged were copper-wire ropes 

 of various lengths, but of the same diameter 

 and construction as those used for the aerial 

 connection. Mr. Wilde's experiments with 

 these contrivances were very numerous, and 

 the general conclusions at which he arrived 

 can only be given here. He regards the fact 

 as established, that currents of electricity of 

 great quantity, but of an intensity below that 

 which is required to effect the electrolyzation 

 of the liquid in which the conductors are sub- 

 merged, may be transmitted to considerable 

 distances without the necessity of surrounding 

 the conductors with an insulating envelope. 

 But he remarks that it is impossible for him to 

 say, without further experiments with con- 

 ductors of much greater length than those em- 

 ployed by him, whether it would be practicable, 

 under the most favorable circumstances, to 

 transmit to distant places electric currents 

 sufficiently powerful to be made available for 

 any useful purpose, under such conditions. 

 One of his experiments on naked copper 

 wires, 750 feet long, in water, is worthy of 

 mention. When currents of high tension were 

 sent through these wires, a marked diminution 

 of electrodynamic effects was observed at 

 the other ends of the wires, but currents of 

 low tension passed over the wires with but lit- 

 tle diminution of their primitive intensity. 

 Using the current from a 10-inch intensity ar- 

 mature, a sufficient quantity of electricity was 

 transmitted through the wires to produce a 

 Brilliant electric light, and to melt 22 inches of 

 iron wire, .050 of an inch thick. With the 

 current of lower intensity from a 5-inch quan- 

 tity armature, 7 inches of the same wire, .035 

 of an inch in diameter were melted. 



Electric Lights for Light-houses and Ships. 

 M. Ernest Saint Edme presented this subject 

 in a communication to the September number 

 of the Annales du Genie Civil. He says that, 

 since the report made by M. Reynaud, director 

 of the administration of light-houses in France, 

 three years ago, electric lighting in light- 

 houses, etc., has not achieved much progress. 

 The reasons of this are stated by the author as 

 follows: To transform existing light-houses, 

 existing apparatus must be sacrificed for a sole 

 advantage of increasing the light at any mo- 

 ment. It is doubtful whether all light-houses 

 are large and strong enough for the accommo- 

 dation of the new machinery; this is certainly 

 the case with most of those on the French 

 coast. As to the light-houses of inferior order, 

 it would be illusory to think of altering them. 

 And other difficulties are inherent in electric 

 lamps, which, however well designed, are sub- 

 ject to causes of derangement which render 

 necessary the best mechanism ; and the cray- 

 ons, if impure, may scale, and cause interrup- 

 tions ; and these impurities might cause mis- 

 takes incompatible with the service of the light- 

 house. When a new light-house is to be built, 

 it will be advantageous to adopt the electric 



