44 



SCIENTIFIC INTELLIGENCE. 



[1§52. 



and, 80 far as our present eiperienca goes, unlimited power of an 

 electro-magnet in sustaining weights attached to an armature in contact 

 with it has, in different countries, and at various times, induced invent- 

 ors to adopt C(nitrivances for pressiiig this agent into service as a 

 labouring force ; and experiments on a small scale liave repeatedly 

 led to the nio.»t sanguine expectations. A more rigid investigation has 

 hitherto, however, proved tlie fallacy of these expectations, ai d the 

 attempt to construct engines on a 'arge scale been abandoned. Prof. 

 Page's maciiine may, perhaps, be considered an exception to this 

 remark, as it is well known that he has constructed and publicly exhi- 

 bited a powerful working engine. Practical difficulties, however, seem 

 to have intervened, or we should, doubtless, have seen it in extensive 

 operation, the more especially as the magnificent grant of the American 

 Government in aid of the professor's researches precludes the BUpposi- 

 tion that they are stoppiid fur want of pecuniary resources. 



It would occupy too much space to enter into a detailed historical 

 account of clectm-niagnetic engines. Tlie means adopted, however, 

 may be classed under two heads ; — 1. Those involving the direct action 

 of an eloctro-magnet on its armature; and 2, those which employ a 

 Beconda:y action ; thus the rotatory ergines of Davenport. Jacobi, and 

 the more recent elegant arrangement of Prof. Wlieatstone, depend for 

 their action upon a series of armatures, passing successively in front of 

 stationary niagnets, or vicevei'sa; whilst that of Prof. Page depends 

 upon the tendency of a bar of soft iron to place itself in a state of 

 magnetic equilibrium, with reference to a succession of helical coils, 

 through which, one after the other, the galvanic current is caused 

 to pass. It may, however, be shown by experiment that this latter 

 force, as well as that of an armatuie, passing in a circle concen- 

 tric with a row of electro-magnets, is far inferior to that with which 

 an electro-magnet attracts an armature, placed at right angles to its 

 axes. This direct action was the first employed as a motive power; 

 unsuccessfully, however, in consequence of the extremely smdl dis- 

 tance to which the magnetic energy extends. Could this diOiculiy be 

 Burraounted, i.o reason can be given why engines of any amount of 

 power may not be constructed. In order to effert this object. Dr. 

 Kemp introduces two contrivances, which may be used separately or 

 conjointly, for the purpose of transferring the magnetic force. In the 

 first place, a series of bars of iron, or armatures, are so arranged that 

 they may successively come within the range of the lines of four of an 

 equal nuiu er of electro-magnets, and so placed as that, in the course 

 of their approach to the magnets, they cut the greatest possible num- 

 ber of magnetic curves. A further arrangement provides fur the action 

 of these armatures, by stems and stops, upon an armature plate, which 

 is, in its turn, secured to the piston-rod of a cylinder filled with fluid. 

 As the piston ascends, or descends, the fluid is forced into another 

 longer cylinder, provided with a rod, which is brought by any suitablo 

 contrivance into connection with a crank, by which machinery may 

 be caused to move. Instead of reciprocating motion, rotatory motion 

 may at once be effected by means of a suitable disc. Tlie whole 

 inventi<pn then rests upon two facts, which cannot he disputed — 1. 

 That an electro-magnet is capable of attracting a considerable weight 

 for a shmt distance ; and 2, that this force may be transferred to 

 machinery by means of incompressible fluids, or practic; lly such. 



Should it be found that this power can be economically af plied, 

 immense advantages must accrue from its use. Tho whole of the spaco 

 occujjicd by fuel and boilers will be rendered available for passengers 

 or freightage : and tho value of this in one case almic — that of tho 

 Asia — will be iepresen:cd by the enormous sum of £3200, at £4 per 

 ton, for each voyage across the Atlantic. Its perfect safety, and fiee- 

 dom of risk from file, must also recommend it especially for emi"-rant 

 ships. In the locomotive department, the compactness and compara- 

 tive lightness of iheulectro-magnutic engine must induce itssubsliluiion 

 for the motive-power now ill use. For canal navigation, this element 

 of lightmss must also be n great rccommendatiun ; and this species of 

 prnperly, so much depreciated by tlie competition ol railways, may yet 

 ba rendered lii^hly productive. For fire-engines, in connection with 



Gwynne's admirable centrifugal pump, it must be extremely Bcrvice- 

 able, as it can be useJ in localities where, from want of working room, 

 or the presence of irrespirable gases, the ordinary engine would be 

 inadmissable. For all kiiids of agricultuial machinery, quartz crushing 

 machines, mills, printing presses, and numberless other minor uses, its 

 value must be apparent ; whilst the lessening of insurance expensea 

 would, in many cases, pay the cost of the engine, and defray the 

 expenses of its working. 



Coaling avd Ornamenlivg Zinc. — A patent has been taken out by Mr_ 

 F. H. Greenstreet. of Albany street, for coating and ornamenting zino 

 surfaces by means of acids alone, or in combination with other matters. 

 The solution may be applied by s))rinkling, dabbing, sprea 'ing, or 

 marbling ; and the surfaces are capable of further ornamentation by 

 painting. Muriatic acid, diluted with water to about 1-114 specific 

 gravity, gives a light ash colour ; chrome yellow, with the same acid^ 

 a yeUowish grey ; Saxonj' green, mixed gradually with the acid to a 

 paste, andstiired until effervesence ceases, produces greenish iron grey ; 

 white lead with the iicid, or Kremintz white, gives a grey coating ; the 

 acid with sulphur produces a yellowish white. Butler of antimony 

 gives a black colour, but when m xeJ with the other pigments does not 

 effect them ; but makes a good ground work. The surfaces having 

 been coated, should be protected by a coat of varnish. Copal may bo 

 used, but the patentee prefers a preparation of wax, as effectually pre- 

 venting oxidation. 



The Electric Cluck. 



The following engraving illustrates the application of electricity in 

 moving tho pendulum of Mr. Bain's electric clock. The pendulum a is 

 drawn in dotted outlines. The bob of the pendulum 6 is a brass box 

 containing a coil of covered copper wire on a bobbin ; and cc repre- 

 sent permanent bar- magnets projecting from opposite sides of the 

 cl"ck-cnse in the centre of the pendulum bob ; while rf is a voltaic 

 pair with the current shown by arrows. Dr. Wilson in his work oa 

 electricity, gives the following account ot the operation : — 



"A wire from the cop])er is conducti d to the top of the pcndulara- 

 rod, then down its left-hand side to the bob, in which it is coiled many 

 times, and then ascending on the right side to the tup of the perdulum- 

 rod, it is brought down within the clock-case, and terminates in a disc 

 c made of grooved ag:itc. The black dot in the groove represents a 

 ( old stud which forms the term. nation c f the wire from the copper 

 / is a second grooved disc, made, however, entirely of metal, from 

 which a wire proceeds to the zinc. The current thus can only pass, if 

 a metallic bridge stretches from the disc/ to Ihc gold stud in the ditc*. 

 This bridge g g stands on the grooves in the two discs, the kft citrein- 



