href="@public@vhost@g@gutenberg@html@files@45446@[email protected]#IllPage_31" class="pginternal" tag="{http://www.w3.org/1999/xhtml}a">31

Gilbert's orb of virtue, 1600 32 Behavior of compass-needle on a terrella or spherical lodestone 44 Gilbert's "versorium" or electroscope 69 Gordon's electric chimes, 1745 75 Modern form of Leyden jar, with movable coatings 87 Three coated panes in series 89    "     panes in parallel 89    "     jars in parallel 90    "     jars in cascade 90 Discharge by alternate contacts 94 Tassel of long threads or light strips of paper 101 Procopius Divisch (1696-1765) 108 The Divisch lightning conductor (1754) 111 Set of pointed rods 112 Galvani (portrait) opposite page 133 Volta      "      "      " 162 Oersted      "       "      " 205 The Magnetic effect of an electric current 209 Magnetic field surrounding a conductor carrying a current 212 Magnetic whirl surrounding a wire through which a current is passing 213 Ampère's molecular currents 214 The "sympathetic telegraph" from Cabeo's Philosophia Magnetica, 1629 216 The "sympathetic telegraph" from Turner's Ars Notoria, 1657 218 Ampère (portrait) opposite page 232 Faraday      "      "      " 299 Clerk Maxwell (portrait) opposite page 334 Lord Kelvin      "      "      " 361

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MAKERS OF ELECTRICITY.

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CHAPTER I.
Peregrinus and Columbus.

The ancients laid down the laws of literary form in prose as well as in verse, and bequeathed to posterity works which still serve as models of excellence. Their poets and historians continue to be read for the sake of the narrative and beauty of the style; their philosophers for breadth and depth of thought; and their orators for judicious analysis and impassioned eloquence.

In the exact sciences, too, the ancients were conspicuous leaders by reason of the number and magnitude of the discoveries which they made. You have only to think of Euclid and his "Elements," of Apollonius and his Conics, of Eratosthenes and his determination of the earth's circumference, of Archimedes and his mensuration of the sphere, and of the inscription on Plato's Academy, Let none ignorant of geometry enter my door, to realize the fondness of the Greek mind for abstract truth and its suppleness and ingenuity in mathematical investigation.

But the