Modern Practice of the Electric Telegraph: A Technical Handbook for Electricians, Managers, and Operators, with 185 IllustrationsD. Van Nostrand Company, 1891 - 234 стор. |
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action adjustment ampères ance apparatus armature artificial line battery brass closed coil conductor connected contact-points convenient copper plate copper wire core Daniell cell deflection diagram diameter direction distant end distant station dots dynamo dynamo-electric effect electric circuit electric current electric telegraph electro-magnet electromotive force employed equal gauge glass ground helix hence hydrometer illustration insulation leaky line length less lever line-wire lines of force loop magnetic field magnetic force measured megohms ment metallic miles neutral relay number of cells number of turns Ohm's law ohms operator pegs placed polar relay pole position practical principle produced proportion quadruplex quantity of current ratio rheostat s. c. solution screws shown in Fig shunt signals single-current sounder switch Tangent Galvanometer telegraph line telegraphic circuit termed terminal station thick tion transmitting unit usually vertical voltaic volts way-station Western Union Wheatstone Bridge zinc zinc plate
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Сторінка 36 - I often say that when you can measure what you are speaking about and express it in numbers you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.
Сторінка 37 - Gauss' principle of absolute measurement for magnetism and electricity, is merely an extension of the astronomer's method of reckoning mass in terms of what we may call the universalgravitation unit of matter; and of the reckoning of force adopted by astronomers, in common with all workers in mathematical dynamics, according to which the unit of force is that force, which, acting on unit of mass for unit of time, generates a velocity equal to unit of velocity.
Сторінка 2 - ELECTRICITY and Magnetism are not forms of Energy ; neither are they forms of Matter. They may perhaps be provisionally defined as properties or Conditions of Matter; but whether this Matter be the ordinary matter, or whether it be, on the other hand, that...
Сторінка 221 - ... writing, and each correcting the faults of the other. The sounds of the code characters must first be learned separately and then short words chosen, which must be written very slowly and distinctly and well spaced, the speed of manipulation being gradually increased as the student becomes more proficient in reading.
Сторінка 36 - IN physical science a first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality connected with it. I often say that when you can measure what you are speaking about and express it in numbers you know something about it ; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a...