May 31, 1900] 



NATURE 



117 



intense electrical oscillations which pass throuc;h the coil shown, 

 and violently agitate the electrified molecules of the air. By 

 this means a strong affinity is created between the two normally 

 indifferent constituents of the atmosphere, and they combine 



\ readily, even if no further provision is made for intensifying 



I the chemical action of the discharge. 



*■ Under certain conditions the atmosphere, which is normally 



a high insulator, assumes conducting properties, and so becomes 

 capable of conveying any amount of electrical energy. The 

 discovery of the conducting properties of the air, though unex- 

 pected, was only a natural result of experiments in a special 

 field carried on for some years previously. It was during 

 1889 that certain possibilities, offered by extremely rapid 

 electrical oscillations, led to the design of a number of special 

 machines adapted for their investigation. One of ihe earliest 

 observations made with these new machines was that electrical 

 oscillations of an extremely high rate act in an extraordinary 

 manner upon the human organism. Thus, for instance, power- 

 ful electrical discharges of several hundred thousand volts, 

 u hich at that time were considered absolutely deadly, could be 

 ssed through the body without inconvenience or hurtful con- 

 L-quences. Another observation was that by means of such 

 oscillations light could be produced in a novel and more eco- 

 nomical manner, which promised to lead to an ideal system 

 of electric illumination by vacuum-tubes, dispensing with the 

 necessity of renewal of lamps or incandescent filaments, and 

 possibly also with the use of wire-; in the interior of buildings. 



■ • 2. — The coil, partly shown in the photograph, creates an alternating 

 current of electricity at the rate of 100,000 alternations per second. 

 The discharge escapes with a deafening noise, striking an unconnected 

 coil 22 feet away, and creating such an electrical disturbance that sparks 

 an inch long can be drawn from a water-main at a distance of 300 feet 

 from the laboratory. 



rhe investigations led to other valuable observations and re- 

 ills, one of the more important of which was the demonstration 

 <f the practicability of supplying electrical energy through one 

 uire without return. To what a degree the appliances have 

 been perfected since the demonstrations in 1892, when the ap- 

 paratus was barely capable of lighting one lamp, will appear \ 

 from the fact that as many as four or five hundred lamps have ! 

 sn lighted in this manner. I 



le success of this method of transmission suggested that the 

 could be used as a conductor, thus dispensing with wires. \ 

 earth was regarded as an immense reservoir of electricity, 

 ch could be disturbed effectively by a properly designed 

 'rical machine. Accordingly efforts were directed toward 

 :ting a special apparatus which would be highly effective in 

 ting a disturbance of electricity in the earth, and a novel 

 of transformer or induction-coil, particularly suited for this 

 ial purpose, was designed. By means of this apparatus, it 

 icticable, not only to transmit minute amounts of electrical 

 for operating delicate electrical devices, but also electrical 

 ;y in appreciable quantities. 



lowever extraordinary the results exemplified by Fig. 2 may 

 _ they are but trifling compared with those which are 



"tainable by apparatus designed on these same principles. 



NO. 1596, VOL. 62] 



Electrical discharges have been produced, the actual path of 

 which, from end to end, was probably more than one hundred 

 feet long ; but it would not be difficult to reach lengths one 

 hundred times as great. Electrical movements occurring at the 

 rate of approximately one hundred thousand horse- power have 

 been obtained, but rates of one, five, or ten million horse-power 

 are easily practicable. 



The most valuable oliservation made in the course of these 

 investigations was the extraordinary behaviour of the atmosphere 

 toward electric impulses of excessive electromotive force. The 

 experiments showed that the air at the ordinary pressure became 

 distinctly conducting, and this opened up the wonderful prospect 

 of transmitting large amounts of electrical energy for industrial 

 purposes to great distances without wires, a possibility which, 

 up to that time, was thought of only as a scientific dream. 

 Further investigation revealed the important fact that the con- 

 ductivity imparted to the air by these electrical impulses of many 

 millions of volts increased very rapidly with the degree of rare- 

 faction, so that air strata at very moderate altitudes, which are 

 easily accessible, offer, to all experimental evidence, a perfect 

 conducting path, better than a copper wire, for currents of this 

 character. 



The experiments have indicated that, with two terminals 

 maintained at an elevation of not more than thirty thousand to 

 thirty-five thousand feet above sea-level, and with an electrical 

 pressure of fifteen to twenty million volts, the energy of thou- 

 sands of horse-power can be transmitted over distances which 

 may be hundreds and, if necessary, thousands of miles. Investi- 

 gations are now being carried on with the object of reducing 

 considerably the height of the terminals now required. 



SOME SCIENTIFIC ASPECTS OF TRADE. 



A REPORT on the trade and commerce of Leghorn, for the 

 -^"^ year 1899, by Mr. Vice-Consul Carmichael, has just been 

 received at the Foreign Office and published as No. 2714 of the 

 Annual Series. The following extracts from the report are of 

 interest as showing the various points at which scientific work 

 and knowledge touch industry. 



The proportion of sulphate of copper imported from Great 

 Britain in 1898 was 96 per cent.; it had in 1899 fallen to 76 per 

 cent. The explanation of this unwelcome fact appears to be 

 due to keen United States competition. Italian manufacture is 

 likely to become an even more formidable danger in the near 

 future. Manufacturers appear as a rule to have gone to England 

 for the greater part of the raw material, and that of itself was a 

 handicap. Now, however, the flourishing and influential 

 Societa Metallurgica of Leghorn is busily erecting the neces- 

 sary plant for the manufacture of sulphate of copper on a large 

 scale. Italy produces some 26,000 tons of copper annually, 

 and it is said that the company can depend upon securing its 

 material at home. Should this be the case it will at once be 

 seen how formidable a competitor is entering the field. In any 

 case the more satisfactory days of the English trade in sulphate 

 seem to be over. 



As this series of reports is yearly obtaining a larger circulation 

 it may perhaps be necessary to state that the wood from which 

 briar pipes are made is not the root of the briar rose, but the 

 root of the large heath known in botany as the Erica arborea. 

 Our "briar" is but a corruption of the French " bruyere." 

 The briar-root industry has had a somewhat curious history. 

 First begun in the Pyrenees some 50 years ago,, it travelled along 

 the French Riviera and the Ligurian coast (taking Corsica by 

 the way) to the Tuscan Maremma, and has now reached Calabria 

 in the south, which is at present its most flourishing centre. By 

 the very nature of the business, when a certain district has been 

 exhausted of all its roots, the industry must come to an end 

 there, and I have heard the opinion expressed that the Italian 

 branch of it cannot last much more than another ten years. 

 Leghorn has always been the centre of the export of Tuscan 

 briar- root since the Maremma industry came into existence, 

 but as the South Italian briar is of admittedly superior quality, 

 a large quantity of the Calabrian root is also imported into 

 Leghorn for selection and subsequent export. 



The olive oil crop throughout Tuscany, small as it promised 

 to be, has, I regret to say, been more than -half destroyed by 



