14 REPORT — 1867. 



electi-ic regulator would yield aligit equal to about 35 Grove's or Bimsen's elements, 

 the driving-power expended being less than one horse. 



1 have also constructed another form of machine, on the same principle as that 

 described above, but instead of having two independent armatm'es running in sepa- 

 rate gi'ooves, they are hxed end to end, so as to appear like one continuous anna- 

 ture, but so placed with reference to each other that their magnetic axes shall be 

 at riglit angles. By this an'angement there is only one opening required for the 

 armature, enabling full advantage to be taken of the horseshoe form of electro- 

 magnet. The shoes of the electromagnet and armatures are so proportioned to 

 each other that there is an actual break in the magnetic circuit with reference to 

 each armature alternately, but by their disposition at light angles there never is an 

 actual break in the complete mag-netic circuit ; simply a shifting occm's of the prin- 

 cipal portion of the magnetic force from one armatm-e to the other at the precise 

 moment requii'ed to produce the best effect. The mechanical advantages to be ob- 

 tained by this disposition of parts must be at once obvious, as one pair of bearings 

 and a set of driving gear are dispensed with, and from the lixing oi the two arma- 

 tures together the currents are made to iiow perfectly isochronous with each other. 

 It may be found advantageous to vary the angle of position of the arjnatures with 

 reference to eacli otlier, according to the speed at whicli they are driven, so that tlie 

 cm-rent given oti'by the exciting armature may at the precise moment exert its full 

 eflect upon the electromagnet, and thus produce the bast eiiect in the second ar- 

 matui'e. 



0)1 a 2Iafjneto-Elcctric Machine. By "Willtaji Ladd, F.B.A.S. 



i 



On the Phenometm wliich occur when Mcn/netized Steel is dissolved in Acids. 



By Dr. T. L. PniPsox. 



Notice of a proposal to illutninate Beacons and Buoys by Electricity, conveyed 

 throuyh Submarine Wires connected ivitJi the Shore. By T. Stevenson, 

 E.It.S.E., M.I.C.E. With a description of the Induction-Spa rJc Apparatr.s 

 used for this purpose in the first experiments made for the Northern Liyhts 

 Board, (dso the Electriccd Apparatus recently desiyned for the Northern 

 Liyhts, by C. "W. SrEME^'s, F.It.S. 



The gTcat expense of such lighthouses as the Eddystono and Bellrock has rendered 

 it necessary for the sailor to be contented in many places of danger with a simple bea- 

 con or floating buoj-, which, being invisible at night, ceases to be useful at tiie 

 very time of .all others when a guide is most needed. Various expedients for light- 

 ing these sea-marks, such as camphiue lamps and phosphorescent oils capable of 

 emitting a dull light in the dark, have been proposed. In January 18-54 I pro- 

 posed in Trans. Koy. Scot. Soc. Arts to lay gas-pipes between the shore and the 

 beacon and " submarine electric wires for illuminating a lantern placed in a beacon 

 or buoy." As stated in that paper, however, " I dismissed such schemes from my 

 mind ; for independently of many other difficulties attending them, they are open to 

 one ground of objection, which, at least in the present state of our knowledge, 

 seems insurmountable. This is based on what may be called an axiom in light- 

 house engineering, viz. that it is better to exhibit no light at all than one which 

 is liable to be often extinguished." 



Under these circumstances I at that time suggested an entirely different method 

 of illuminating beacons, namely, a beam of parallel rays of light projected from 

 the shore upon optical agents placed upon the beacon at sea, and capable of 

 spreading the rays over any required angle in azimuth, so as to produce a mock cr 

 apparent light. This method has been in use at Stornoway Loch without any 

 accident or failure for the last fifteen years. There are, however, certain places 

 where this apparent or mock light is not very suitable, owing to the primary light 

 and reflected light being nearly in line. This consideration, coupled ■ndth the im- 

 pro\ement3 which have subsequently taken place in electrical appliances, led me, 

 in 18(35, in a report to the Northern Lights Board on the magneto-electric light, to 



