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On a new and constant thermo-electric generator
8
Editorial.
was adopted April 1st, 1871. The general card costs 4 schillings ( 2"4 cts) and the district card 2 schillings ( 1"2 cts ). In Russia, postal cards were introduced January 1st, 1872. The general card is furnished at 5 kopecks ( 4 cts ) and the district card at 3 kopecks ( 2"4 cts. ) In Austria, the postal card costs 2 kreutzers ( one cent. ) The system was adopted in October, 1-869, and the first year eight millions of cams were sold. Spain has decided upon postal cards ; Greece and Portugal are abont to issue t h e m ; a n d in Italy the same course has been resolved upon. Turkey alone has thiled to see the advantages of the postal system and to adot)t it.
On a N e w and Constant Thermo-Electric Generator. The dire(.t production of electricity from heat, and its utilization in practice as a source of power, has not, until now, been a commercial success. Unquestionably the best thermo-electrlc combination thus far obtained is that of Mr. Farmer, of Boston, in which an alloy of zinc and antimony constitutes tile positive, and German silver or copper the negative plate. Such all electro-motor was exhibited at the Paris Exposition of 1867, and excited great interest. The difficulty, however, in their use on the large scale lies in the fact that when in action they lose their activity rapidly and " r u n down." Clamond has lately investigated the reason of this, and he finds it to be due to two canses: first, to the oxidation of the surfaces of contact of the two bars under the influence of the heat; and, second, to the cracking of the crystalline bar and its breaking into transverse sections. While, therefore, the electro-motive force of the apparatus undergoes no diminution, the internal resistance is so increased as to render the combination useless after a little time. The first of these difficulties C]amond has overcome bv making some oblique cuts in the end of the flexible plate, and bending the intermediate tongues alternately to either side. When the melted metal is poured ronnd this plate it flows into the spaces thus enclosed, and makes a more perfect contact. The second cause of deterioration was not so easily overcome. Annealing was found to be of' no use, and it was finally ascertained that to render the bars honmgeneous, crystallization must be prevented. This was eflbctcd by heating the mouhls in which the zinc-antimony bars were cast, to a temperature near that at which the alh)y fnses, and by pouring in the metal at a temperature ]mar its solidifying point. In this way, using the zlnc-antimony alloy in connection with strips of
1tows and A'ovelties.
9
iron, the author tins succeeded in constructing a thermo-eleetrie generator, which remained in action in the laboratory of M. Jamin, at the Sorlmnne, tbr six entire months without deterioration. This apparatus consisted of three rings, each composed of ten pairs of bars, arranged radially. In the interior cylindrical space was placed an earthenware tube fidl of holes, serving as a gas-burner. The entire apparatus weighed about 14 pounds, and at an expense per hour, of six cubic t)et of gas, costing in Paris one cent, it deposited two-thirds of a troy ounce of copper; being equivalent to a Bunsen cell seven inches high.
Duchemin's C i r c u l a r C o m p a s s . - - A new compass has been invented in France by M. Duchemln, the nmgnetic force of which resides, not in tt bar or needle, as in the ordinary instrument, but in a fiat steel ring, magnetized, with its poles at two opposite extremities of the same diameter. This ring, supported upon an aluminum traverse, pivoted on agate at its centre, has attached to it the ordinary compass card, and acts promptly and efficiently. The author claims tl)r it the tbllowing advantages: (1) a magnetic power, double that of a needle whose length is that of the diameter of the ring; (2) two neutral points instead o£ one, as in the needle ; whence it happens that none of the magnetism escapes, and that strong sl)arks like those from the Holtz machine do not derange the poles; (3) a better and more prompt perfi)rmance of the eolnpass, the card seeming to float, as it were, in a liquid; (4) a large increase in the sensitiveness of the instrument; (5) the ability to regulate the magnetic intensity of the ring, and thus to compensate tbr local causes. This is eit~ected I)v means of a second magnetized steel ring, snmller than, and inside oI, the first, the positiou of which--and therefore its neutralizing action--may be easily adjusted. Under the direction of the Minister of the Marine, a trial trip of the new compass was luade on the steamboat Faon with very satist:actorv results. 31. l)uchemin now 1)roposes, as an iml)rovcment, the use of a set of such rings, forming a spherical or spheroidal system of still greater magnetic power. The Pernot Rotary Puddling : F u r n a c e . - - A new puddling apvaratus , designed and constrncted bv M. Pernot, has beeu brought to tile notice of tile Society of Civil Engineers of France. In this furnace, charges of 18 cwt. of fine iron obtained fi'om charcoal pig, or 22 ewt. of ordina W iron made from eomnmn pig, are obtained at each operation. The production varies "recording to the nature of the pig
Editorial.
was adopted April 1st, 1871. The general card costs 4 schillings ( 2"4 cts) and the district card 2 schillings ( 1"2 cts ). In Russia, postal cards were introduced January 1st, 1872. The general card is furnished at 5 kopecks ( 4 cts ) and the district card at 3 kopecks ( 2"4 cts. ) In Austria, the postal card costs 2 kreutzers ( one cent. ) The system was adopted in October, 1-869, and the first year eight millions of cams were sold. Spain has decided upon postal cards ; Greece and Portugal are abont to issue t h e m ; a n d in Italy the same course has been resolved upon. Turkey alone has thiled to see the advantages of the postal system and to adot)t it.
On a N e w and Constant Thermo-Electric Generator. The dire(.t production of electricity from heat, and its utilization in practice as a source of power, has not, until now, been a commercial success. Unquestionably the best thermo-electrlc combination thus far obtained is that of Mr. Farmer, of Boston, in which an alloy of zinc and antimony constitutes tile positive, and German silver or copper the negative plate. Such all electro-motor was exhibited at the Paris Exposition of 1867, and excited great interest. The difficulty, however, in their use on the large scale lies in the fact that when in action they lose their activity rapidly and " r u n down." Clamond has lately investigated the reason of this, and he finds it to be due to two canses: first, to the oxidation of the surfaces of contact of the two bars under the influence of the heat; and, second, to the cracking of the crystalline bar and its breaking into transverse sections. While, therefore, the electro-motive force of the apparatus undergoes no diminution, the internal resistance is so increased as to render the combination useless after a little time. The first of these difficulties C]amond has overcome bv making some oblique cuts in the end of the flexible plate, and bending the intermediate tongues alternately to either side. When the melted metal is poured ronnd this plate it flows into the spaces thus enclosed, and makes a more perfect contact. The second cause of deterioration was not so easily overcome. Annealing was found to be of' no use, and it was finally ascertained that to render the bars honmgeneous, crystallization must be prevented. This was eflbctcd by heating the mouhls in which the zinc-antimony bars were cast, to a temperature near that at which the alh)y fnses, and by pouring in the metal at a temperature ]mar its solidifying point. In this way, using the zlnc-antimony alloy in connection with strips of
1tows and A'ovelties.
9
iron, the author tins succeeded in constructing a thermo-eleetrie generator, which remained in action in the laboratory of M. Jamin, at the Sorlmnne, tbr six entire months without deterioration. This apparatus consisted of three rings, each composed of ten pairs of bars, arranged radially. In the interior cylindrical space was placed an earthenware tube fidl of holes, serving as a gas-burner. The entire apparatus weighed about 14 pounds, and at an expense per hour, of six cubic t)et of gas, costing in Paris one cent, it deposited two-thirds of a troy ounce of copper; being equivalent to a Bunsen cell seven inches high.
Duchemin's C i r c u l a r C o m p a s s . - - A new compass has been invented in France by M. Duchemln, the nmgnetic force of which resides, not in tt bar or needle, as in the ordinary instrument, but in a fiat steel ring, magnetized, with its poles at two opposite extremities of the same diameter. This ring, supported upon an aluminum traverse, pivoted on agate at its centre, has attached to it the ordinary compass card, and acts promptly and efficiently. The author claims tl)r it the tbllowing advantages: (1) a magnetic power, double that of a needle whose length is that of the diameter of the ring; (2) two neutral points instead o£ one, as in the needle ; whence it happens that none of the magnetism escapes, and that strong sl)arks like those from the Holtz machine do not derange the poles; (3) a better and more prompt perfi)rmance of the eolnpass, the card seeming to float, as it were, in a liquid; (4) a large increase in the sensitiveness of the instrument; (5) the ability to regulate the magnetic intensity of the ring, and thus to compensate tbr local causes. This is eit~ected I)v means of a second magnetized steel ring, snmller than, and inside oI, the first, the positiou of which--and therefore its neutralizing action--may be easily adjusted. Under the direction of the Minister of the Marine, a trial trip of the new compass was luade on the steamboat Faon with very satist:actorv results. 31. l)uchemin now 1)roposes, as an iml)rovcment, the use of a set of such rings, forming a spherical or spheroidal system of still greater magnetic power. The Pernot Rotary Puddling : F u r n a c e . - - A new puddling apvaratus , designed and constrncted bv M. Pernot, has beeu brought to tile notice of tile Society of Civil Engineers of France. In this furnace, charges of 18 cwt. of fine iron obtained fi'om charcoal pig, or 22 ewt. of ordina W iron made from eomnmn pig, are obtained at each operation. The production varies "recording to the nature of the pig