68 



SCIENCE. 



[Vol. XI. No. 262 



Antarctic Regions. — The British Government has refused 

 the request of the Australian colonies to grant a subsidy to the 

 proposed Antarctic expedition which was to be organized by a joint 

 effort of the Australian colonies in case the British Government 

 should support the undertaking. This decision will probably post- 

 pone the resuming of Antarctic exploration for an indefinite time. 

 Although it is not probable that results of great commercial value 

 will be obtained by an expedition of this kind, the scientific objects 

 are so great that this new delay must be greatly regretted. 



ELECTRICAL SCIENCE. 



Electricity directly from Heat. 



Attempts to generate electric currents, by utilizing the fact that ' 

 mao^netic metals lose their magnetic properties when sufficiently 

 heated, have been made for some years. It is only recently, how- 

 ever, that such experiments have been made on a practical scale, 

 and with any promise of ultimate success. When we consider that 

 in the most economical source of electricity, the dynamo-electric 

 machine, we transform the energy of our fuel to the energy of 

 steam under pressure, then through the steam-engine to mechan- 

 ical work, and finally by the dynamo to the energy of electrical cur- 

 rents, losing energy in each transformation, our ultimate return be- 

 ing perhaps ten per cent of the energy expended ; when we add to 



In his paper, IVIr. Edison gave no data as to the performance of 

 the machine, except the statement that a generator to feed thirty 

 incandescent lamps would weigh two or three tons. 



Nothing has been heard lately of this generator : it will naturally 

 take time to perfect it and make it practical. 



Within the last month, however, attention has been called to a 

 machine using the same general principle as that of Mr. Edison, 

 but differing greatly in detail, — an invention of M. Menges of the 

 Hague. 



One form consists of a Gramme ring within which is a stationary 

 electro-magnet. The two are horizontal, and are separated by a 

 considerable airspace: this space is filled by a zigzag ribbon of 

 iron extending around the inner circumference of the ring, with 

 which it revolves. Now, if this ribbon of iron be cold, most of the 

 lines of force will pass through it from one pole to the other of the 

 magnet : few will go through the armature. If, however, the rib- 

 bon be heated at points at right angles to the poles, the magnetic 

 resistance will be increased, and most of the lines of force will pass 

 througli the armature : there will be no motion, since every thing 

 is perfectly symmetrical. If, now, the heat be applied to the ends 

 of the same diameter at points forty-five degrees from the pole, the 

 symmetry disappears, and there will be a rotation. Now, the 

 Gramme ring rotating in a field of force will generate currents as in 

 an ordinary dynamo-electric machine. In reality, then, we have a 

 motor-dynamo arrangement, the former transforming the energy of 



STREET-CAR ! 



RIC MOTOR. 



this the complication and expense of a steam-plant, — it would 

 seem that, even if our means of direct conversion is not so eco- 

 nomical as the dynamo, yet if it have any reasonable efficiency, and 

 is simple of construction, it would supplant the older method. 



In August of 1887 Mr. Edison read before the American Associ- 

 ation for the Advancement of Science a paper on pyromagnetic gen- 

 erators. Briefly the principle on which his machine was built is 

 this. If a piece of iron wrapped with wire be put between the 

 poles of a magnet, a number of lines of force will pass through it, 

 and therefore through the coils of the wire, depending directly 

 on the strength of the magnet and on the magnetic permeability 

 of the iron. Now, it is well known that the permeability of iron 

 becomes very nearly zero when it is raised to a bright red heat : so, 

 if we heat the iron, the lines of force through it will decrease, and 

 this decrease will cause an electro-motive force in the coil of wire. 

 When the iron cools, there will be an increase of lines of force, 

 causing an electro-motive force in the opposite direction. Mr. 

 Edison's machine, built on this principle, consists of eight horse- 

 shoe magnets arranged in a circle, the poles facing inward ; and 

 between the poles of each is a roll of thin laminated iron covered 

 with asbestos and wrapped with wire : we will call these the arma- 

 tures. This is placed over a furnace, and beneath it revolves a 

 half-circle of fire-clay, which shields half of the armatures from the 

 heat. If this shield be turned continuously, half of the armatures 

 are being heated while the other half are being cooled ; and the 

 electro-motive forces in the two halves, which would be in opposite 

 directions, are added by a commutating arrangement on the shaft 

 of the shield. A blast of cold air assists the cooling of the arma- 

 tures. 



heat into motion, the latter transforming the energy of motion into 

 electrical energy. 



Both the ' pyromagnetic generators ' of Mr. Edison and M. 

 Menges are an advance on previous machines of this type. It is 

 difficult to see, however, how, in their present form, either can pro- 

 duce any very considerable quantity of electrical energy, with any 

 reasonable size of apparatus. The publication of reliable figures 

 on the performance of these machines would be of great interest. 



Sprague Electric Railway in Richmond. — There was 

 opened for traffic on Feb. 2 an electric street-railroad that from 

 the extent of the plant, the difliiculties overcome, and the perfection 

 of equipment, marks a decided advance in electric traction. The 

 Union Passenger Railway system in Richmond extends from the 

 eastern to the western part of the town, having a total length of 

 track of eleven miles. The road has many curves of short radius. 

 There are grades that reach ten per cent, while there are combina- 

 tions of curves and grades even more difficult than the steepest of 

 the grades. In one case there is a thirty-foot curve on an ascent 

 of seven per cent. In addition to this, but a small part of the 

 length is through paved streets, and in wet weather the mud is so 

 bad that in some places it completely covers the rails. The road 

 is equipped with forty large sixteen-foot cars. Beneath each car 

 are two 7i-horse power motors, one geared to each pair of wheels. 

 The current is taken from an overhead wire by a wheel or trolley 

 of sheet brass fixed on the end of a rod which holds it up under- 

 neath of and in contact with the wire. This rod is fixed on trunn- 

 ions, and is fitted with springs that give a gentle pressure at the 

 contact. The motors, nominally /i-horse power each, are capa- 

 ble of developing over ten-horse power when necessary. They 



