MR EDISWS LATEST INVENTION

Ashburton Guardian, Volume VII, Issue 1721, 28 November 1887, Page 3

MR EDISWS LATEST INVENTION

Mr I£di«on (aaya n correspondent of the l Time3") ha? just crowned hlB remarkable series of iuventious by anchor whloh promises t> work a revolution Id our present methods of dynsmo con&tr notion. He has, m faot, solved a problem which has ocoup e4 tbe attention of electricians for some time past — tbe problem, namely, >>f direc ly tranbforming beat Into eleotricity — of doing away, m short, with tbe existing o'umay m-thod of first transforming heat into motive power by a steam-engine, and using that motive power to drive a dynamo. Mr Edison uaes the heat at first hand. It is the beat itself which drives the dynamo and generates •ho current m it. Hence tbe name 'pyromagnetic," whleh he bas given to the new dynamo and motor, which he brought to the notice of the scientific world at the recent meeting of the American •Vasoclation for the Advancement of Science. As the invention ia ttlll being perfected, we need do little more now th >n explain the principle upon which it ts baaed. It has long been known hat h-at affects the magnetio properties of certain mentis to a considerable degree, notably of Iron, cobalt, and nickel. A pieoa of iron, m f&ot as haß been shown by Professor Hughes, loses its magnetio property when heated to a cherry red, bat regains it on cooling again. It is also known that any variation of the intensity of tha magnetic field pmducoß an electrfo current m a conductor situated m the field. By ingeniously combining these two fact*, Mr Kdieoo has produced an eipctrio motor and a dynamo, m both of which heat is directly applied to vary the intensity ot a magnetic field, and thus to produce an electric current ia the one case, and motive pi wer m the other. Tha motor Is the simpler machine of the two, and con* siats essentially of a permanent magnet having a bundle of small iron tubes placed between its poles, and free to rotate on on axle at right angles to the plane of the mapntt, like the armature of an ordinary dynamo. The walls of these iron tubes are very thin, and hot air ia sucked through them to beat tbem up. The arrangement is such that when all tbe tubes are heated iv this way, there is no motion of the bundle— or, aa we may term it, drum — upon its nxle. Bat by meanß of a Bcrepn cutting < S the heat frcm a part of the bundle of tubes, and revoving round an axle, tbe symmetry of the arrangement id destroyed, and the bundle or drum beiog part cold and part h.ot — that la to say, part magnetio and part nonmagnetic, falls under the unequal influence of the two poles of the permanent magnet and begins to rotata on its axln. It beoomeß m fact, a magnetio, or rathtr, a pyro-aiagnetlo motor. In the generator, which is based on the same principle, tbere are eight electro-magneta arranged radially, aDd having m front of their polea two disks of soft iron wound round with eight rolls of fine wire. When tbe electro-magnets are exited, these disks bee me magnetio by induction and a '

current is generated m the wires. The whole la exposed to the heat of a furnace, and the hot a r traversing •he disks and rolls, demagnetises the disks. By the use of Roreons, however, part of the heat is cut off intermittently, »nd thus, by restoring and taking awny the magDet o property of the disks, by catting nff acid letting on the heat, &n electric curreo Jb maintained m the rolls of wire and onUeoted by means uf a oommnta*or, aa m or^in-ity dynamos. The fi ft|m >tor constructed on this new prin* cip'n wae h-att d by two BuDsen burners ard developed a power of about 95 kilogrammeties a minnte, A larger one weighing abont 750 kilogrammes, and eivlng about three horße-povrer, m nearly finished. Tbe re^olrs hitherto obtained show that the expense of fuel for the lame electric euerpy wi<h tbe pyromagnetic dynnmo will be equal to or less than with the ordinary dynamo and I engine. Moreover, the new power of the new dynamo will be leßs, weight for weight, than that of the ordinary dynamo ; | but, on the other hand, tbe pyro-magnetio dynamo will allow of the wa&+e heat being utilised for other purposes, such as beatmg the building, and bo on,.