86 



NATURE 



\May 2 2, 1879 



cable, say about an inch in diameter, composed of copper 

 wires, each about one-sixteenth of an inch in diameter. 

 The cable will be laid in a trench immediately under the 

 flagging of the side walk, and near the curb ; every 

 twenty-five feet a wire will be dropped to carry the cur- 

 rent into a house, and when the terminus of the cable is 

 reached there will be one wire left. Of course it will be 

 necessary to construct the cable according to the number 

 of houses in each district. As a district increases in 

 population the flagging can be taken up, and a section of 

 cable can be placed alongside the original cable, and 

 joined to it at each end. Thus the new houses can be 

 supplied.' ' Will there not be a loss of electricity by in- 

 duction or the influence of the earth ? ' ' None whatever. 

 And now I will tell you another thing. It is perfectly 

 easy for me to get a light equal to sixty-six candles from 

 each of my lamps : but I limit them to six.' ' Will not 

 the construction of your station and your cables be very 

 costly?' 'No ; and if it were, the profits would warrant 

 the outlay.' " 



Copper wires one-sixteenth of "an inch in diameter— the 

 same size as those often used for telegraphic purposes- 

 are to convey currents of electricity to light up lamps 

 whose resistances are as 192 to i as compared with carbon, 

 or as 100 to I as compared with the conductor. The 

 resistance of the copper wire is about 13 ohms per mile. 

 What current will be required to produce a light of 66 

 candles a mile off under such 'conditions ? An electro- 

 motive force of a 1,000 volts would not do it, and the very 

 best machines do not much exceed 100 volts in this 

 respect. Where is the power to come from ? Mr. 

 Edison now proposes to have 30 of his new dynamo 

 machines worked by his 80-horse-power steam-engine, 

 lighting up 400 lights. In other words, each machine is 

 to produce about 13 lights, and to absorb 2% horse-power. 

 This shows that his experience is gradually bringing him 

 down to the limits of our experience in France and 

 England, where for some time past one machine lights up 

 twenty lights, but with an expenditure of 23-hor3e power. 

 It also shows that he was premature in announcing the 

 solution of the indefinite subdivision of the light, and tha- 

 he would have done well to have worked upon the expet 

 rience of others rather than have learnt that experience 

 himself by an immense expenditure of time and money. 

 The electric light, theoretically and practically, is un- 

 questionably more advanced in Europe than it is in 

 America. 13ut even here the progress in lamps is very 

 slight. 



Col. Bolton, in a remarkable paper read at the last 

 meeting of the Society of Telegraph Engineers, has 

 shown that electric light manias are not only periodic, but 

 that the very same inventions are to a certain extent, 

 also periodic. Thus he showed that everything that 

 Mr. Edison has patented has been patented before in 

 England. 



NOTE AS TO DISTINGUISHING CHARACTER- 

 ISTICS FOR ILLUMINATED BUOYS 



'T'HE plan of illuminating by means of Pintsch's 

 ■»■ system of forcing gas into floating buoys having 

 now been tried by the Trinity House and by the Harbour 

 Authorities of the Tay, I have lately been engaged in 

 considering the best means of distinguishing one buoy 

 from another. 



The plan which occurred to me was to make the flow of 

 the gas produce automatic intermittent action, and for this 

 purpose some form of gas meter seemed to promise best. 

 I applied to Messrs. Milne, gas engineers, Edinburgh, 

 to give me their assistance in the matter, and they have 

 succeeded in making a modification of a dry meter which 

 has been tried and found to work very satisfactorily. By 

 this arrangement a small supply of gas keeps a small jet 

 constantly illuminated a little above the principal burner, 



and when, by the valve, the full supply of gas is turned 

 on to the large burner, it is ignited by the small jet. 

 The periods of light and darkness can be regulated in 

 any desired proportion. The same object may, however, 

 be effected by means of a single burner, the jet being 

 kept burning in the socket. 



By means, then, of two separate lanterns, one of which 

 has red panes, and the other either white or green, the 

 following characteristics may be produced : — 



Red and white. 

 Red and green. 

 Green and white. 



If, again, only one lantern be used, we shall have — 



Intermittent white. 

 „ red. 



,, green. 



And if to these we add the present single fixed white, 

 red, and green, this would give in all nine characteristics, 

 which would probably be sufficient for any navigation. 



It is proper to add that, in order to prevent oscillations 

 of the apparatus, which would take the light out of the 

 sailor's vision, the apparatus and burner should be made 

 to work in gimbals, as in my steamer's lights. If these 

 gimbals were made hollow, the gas could be easily made 

 to pass up to the burner, but a simpler mode would be to 

 use a flexible tube between the regulator and the burner. 



Thomas Stevenson 



GEOGRAPHICAL NOTES 



Letters from Nordenskjdld have been received by 

 the Governor-General of Siberia. They confirm the news 

 already brought to Europe. The Vega steamship has 

 been blocked by ice in a harbour named Kamen, at a 

 short distance from Behring Straits on the east coast of 

 Siberia. This station is easily reached by whalers every 

 year. No doubt t'le escape of the explorer and his com- 

 1 unions will take place without difficulty as soon as the 

 ice breaks up, probably in a few weeks. The news has 

 been brought by native messengers, and everything was 

 goinL; on well on board the Vega. 



M. Wu; ::;oF has sent to the French Geographical 

 Society a long and exhaustive memoir on the Oxus 

 question. After having studied the question on the spot, 

 the Russian geographer feels certain that the suppression 

 of the Caspian mouth was produced not by a gradual 

 elevation of the country, but by the accumulation of 

 deposits in the bed of the river, and the immense drain- 

 age produced by the development of irrigation in the 

 Khivan Oasis. He feels certain that the restoration of 

 the former state of things would be a very easy work. It 

 would result in the establishment of a new oasis between 

 Khiva and the Caspian Sea. The Oxus being navigable 

 to Balkh, and the Volga being in direct communication 

 with the Baltic, through a system of canals, a water-way 

 would thus be established from St. Petersburg to Balkh, 

 and the stream would connect the Russian capital with 

 the vicinity of their scientific frontier of India. M. 

 Woeikof supposes justly that the restoration of the Oxus 

 to the Caspian would accelerate the retreat of the Aral 

 waters. He believes that shortly after that large opera- 

 tion the area of Aral would be reduced to one-third of its 

 present extent. But he argues that this alteration would 

 not be altogether detrimental to the prosperity of the 

 surrounding countries. 



Though there are no journeys of discovery into the 

 interior to record, some useful geographical and topogra- 

 phical work was done in Western Australia by the Sur- 

 veyor-General's department during the last six months of 

 1878, as we learn by a report just received from Perth. 

 The position of Mount Welcome at Roebourne, on the 

 north-west coast of the colony, was determined to be 



