518 REPORT 1881. 



cent.) of this by the generation and dissipation of heat through the conductor 

 and 21,000 horse-power (or 80 per cent, of the whole) on the recipients at the 

 far end. 



4. The elevation of temperature ahove the surrounding atmosphere, to allow 

 the heat generated in it to escape by radiation and be carried away by convection 

 is only about 20° Centigrade ; the wire being hung freely exposed to air like an 

 ordinary telegraph wire supported on posts. 



5. The striking distance between flat metallic surfaces with difference of 

 potentials of 80,000 volts (or 75,000 Daniell's) is (Thomson's ' Electrostatics and 

 Magnetism,' § 340) only 18 millimetres, and therefore there is no difficulty about 

 the insulation. 



6. The cost of the copper wire, reckoned at Sd. per lb., is 37,000/. ; the interest 

 on which at 5 per cent, is 1,900^. a year. If 5,250 horse-power at the Niagara end 

 costs more than 1,900/. a year, it would be better economy to put more copper 

 into the conductor ; if less, less. I say no more on this point at present, as the 

 economy of copper for electric conduction will be the subject of a special com- 

 munication to the Section. 



I shall only say, in conclusion, that one great difficulty in the way of economis- 

 ing the electrical transmitting power to great distances (or even to moderate 

 distances of a few kilometres) is now overcome by Faure's splendid invention. 

 High potential — as Siemens, I believe, first pointed out — is the essential for 

 good dynamical economy in the electric transmission of power. But what 

 are we to do with 80,000 volts when we have them at the civilised end of 

 the wire ? Imagine a domestic servant going to dust an electric lamp with 

 80,000 volts on one of its metals ! Nothing above 200 volts ought on any 

 account ever to be admitted into a house or ship or other place where safe- 

 guards against accident cannot be made absolutely and for ever trustworthy against 

 all possibility of accident. In an electric workshop 80,000 volts is no more 

 dangerous than a circular saw. Till I learned Faure's invention I could but think 

 of step-down dynamos, at a main receiving station, to take energy direct from the 

 electric main with its 80,000 volts, and supply it by secondary 200-Tolt dynamos or 

 100-volt dynamos, through proper distributing wires, to the houses and factories 

 and shops where it is to be used for electric lighting, and sewing-machines, and 

 lathes, and lifts, or whatever other mechanism wants driving power. Now the 

 thing is to be done much more economically, I hope, and certainly with much 

 greater simplicity and regularity, by keeping a Faure battery of 40,000 cells always 

 being charged direct from the electric main, and applying a methodical system of 

 removing sets of 50, and placing them on the town-supply circuits, while other 

 sets of 50 are being regularly introduced into the great battery that is being 

 charged, so as to keep its number always within 50 of the proper number, which 

 would be about 40,000 if the potential at the emitting end of the main is 80,000 

 volts. 



The following Papers were read : — 



1. On the Possihility of the Existence of Intra-Mercurial Planets.^ 

 By Balfour Stewart, LL.D., F.B.S. 



It is a somewhat frequent speculation amongst tliose engaged in sun-spot 

 research to regard the state of the solar surface as influenced in some way by the 

 positions of the planets. 



In order to verify this hypothesis, observers have tried whether there appear 

 to be solar periods exactly coinciding with certain well-known planetary periods. 



This method has been adopted by the Kew observers (Messrs. De La Kue, 

 Stewart, and Loewy), who had an unusually large mass of material at their dis- 

 posal, and they have obtained from it the following results : — 



1. An apparent maximum and minimum of spotted area approximately corre- 

 sponding in time to the perihelion and aphehon of Mercury. 



' Published in extenso in Nature September 15, 1881. 



