Ce livre historique peut contenir de nombreuses coquilles et du texte manquant. Les acheteurs peuvent generalement telecharger une copie gratuite scannee du livre original (sans les coquilles) aupres de l'editeur. Non reference. Non illustre. 1907 edition. Extrait: ...by the closed circuit sending a current to meet it--a current as yet not divided by the Y, and therefore of twice its strength. Either way, this remainder of incoming current will not act on the relay, to interfere with its signals. This explanation of the ...
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Ce livre historique peut contenir de nombreuses coquilles et du texte manquant. Les acheteurs peuvent generalement telecharger une copie gratuite scannee du livre original (sans les coquilles) aupres de l'editeur. Non reference. Non illustre. 1907 edition. Extrait: ...by the closed circuit sending a current to meet it--a current as yet not divided by the Y, and therefore of twice its strength. Either way, this remainder of incoming current will not act on the relay, to interfere with its signals. This explanation of the duplex system is of course meant to show only its main principle. The adjusting of resistances, and the use of "condensers" to make provision for surplus current, do not affect the main principle and must be explained by technical books. All the reader needs to remember is that duplex telegraphy in its first and simplest form was accomplished by: first, dividing the outgoing current so that its halves neutralized each other in opposite winding as to the home sounder; and, second, allowing the incoming current to act as a whole, since it went in the same direction through both coils of the distant sounder. Of course it makes no difference, in principle, whether the current acts directly on a sounder, or simply opens and closes a circuit that brings the sounder into action. And likewise of the key. This too may either close the circuit of the main line, or may close a circuit that closes a switch that makes a circuit on the main line. Just as in arithmetic the most complicated calculations come down to the four rules--add, subtract, multiply, divide; so, in electric apparatus, the most complicated machines come down to the same simple rules, adding current, by making a weak one bring a strong one into action (by the relay); subtracting, by turning the current into the earth or into a high resistance or making it do work; multiplying, by changing the tension from low to high (by the induction coil, the Leyden jar, and the condenser);...
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Seller's Description:
Not Stated. Very Good Indeed. A nicely bound copy of Tudor Jenks' informative work on electricity for children, illustrated throughout. A children's work. This work looks at electricity, discussing how mankind first came to find the new power, how the learned its ways, and how they invented methods of controlling it. Illustrated with seven plates and numerous in-text illustrations. Written by Tudor Jenks. Jenks was an author, journalist, and lawyer, best known for his prolific fiction and nonfiction works for children. His other nonfiction works include 'Photography for Young People', 'In the Days of Chaucer', and 'The Book of Famous Sieges'. In a full calf prize binding by Woodhouse Grove School, awarded to J. A. Hartley in 1909, with a presentation label to the front pastedown. Collated, incomplete, as lacking the frontispiece. In a full calf prize binding. Externally, smart. Light discolouration to the spine. Minor marks to the spine and boards. The odd spot to the fore edge. Prize label to the front pastedown. Prior owner's stamp to the recto to the front free endpaper, and to the verso to the rear endpaper. Internally, firmly bound. Pages are bright and clean. Very Good Indeed.
