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  7.      <title>The book of science</title>
  8.      <description>Poetry and commentary reflecting on milestones of the history of science, by Tom Sharp</description>
  9.      <link>http://sharpgiving.com/thebookofscience/index.html</link>
  10.      <atom:link href="http://sharpgiving.com/thebookofscience/feed.xml" rel="self" type="application/rss+xml" />
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  13.         <link>http://sharpgiving.com/thebookofscience/index.html</link>
  14.         <title>The book of science</title>
  15.      </image>
  16.      <language>en</language>
  17.      <copyright>Copyright Tom Sharp 2009, 2017</copyright>
  18.      <lastBuildDate>Sat, 20 Jan 2018 12:01:00 GMT</lastBuildDate>
  19.      <pubDate>Sat, 20 Jan 2018 12:01:00 GMT</pubDate>
  20.  
  21.  <!--
  22.  Each item is a weekly feed. We keep only 3 months worth of these.
  23.  -->
  24.  
  25.  <item>
  26.         <title>1855,1865 - "Marangoni effect"</title>
  27.         <description><![CDATA[<strong>Scientists:</strong> James Thomson, Carlo Marangoni<br />
  28. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1855b.html"><img
  29. style="margin-left:10px;vertical-align:top;width:100px;"
  30.  src="http://sharpgiving.com/thebookofscience/iimgs/i1855b.png"
  31. alt="Marangoni effect" /></a><br />
  32. <h2>Marangoni effect</h2>
  33. <pre><font face="arial">The Marangoni effect gives wine legs.
  34. The Marangoni effect stabilizes soap bubbles.
  35. The Marangoni effect does not cause the Cheerios effect
  36.     but helps explains the lava lamp.
  37. The Marangoni effect stabilizes convection cells
  38.     in pots of tomato soup.
  39. The Marangoni effect helps dry silicon wafers
  40.     while processing integrated circuits.
  41. The Marangoni effect makes my leaky faucet drip
  42.     and breaks a falling stream into a sequence of drops
  43.     that a strobe light seems to freeze in place
  44.  
  45. or maybe that&rsquo;s just surface tension and gravity.</font></pre>
  46. <p><a href="http://sharpgiving.com/thebookofscience/items/p1855b.html"><em>More
  47. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  48. <h2 id="commentary">Commentary</h2>
  49. <p>The surface tension of a liquid tends to minimize its surface area.
  50. In weightless space, free-floating liquids are spherical.
  51. </p>
  52. <p>
  53. See also in <em>The book of science:</em></p>
  54. <ul class="bullets">
  55. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1847toc">1847</a>&mdash;<em><a
  56. href="http://sharpgiving.com/thebookofscience/items/p1847.html">Laws of thermodynamics</a></em>&mdash;<a
  57. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Thompson">Benjamin Thompson</a>,
  58. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Carnot">Nicolas L&eacute;onard Sadi Carnot</a>,
  59. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Joule">James Prescott Joule</a>,
  60. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Clausius">Rudolf Clausius</a></li>
  61. </ul>
  62. <p>
  63. Readings on wikipedia:</p>
  64. <ul class="bullets">
  65. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/James_Thomson">James Thomson</a>&rdquo;</li>
  66. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Carlo_Marangoni">Carlo Marangoni</a>&rdquo;</li>
  67. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Marangoni_effect">Marangoni effect</a>&rdquo;</li>
  68. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Tears_of_wine">Tears of wine</a>&rdquo;</li>
  69. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Soap_film">Soap film</a>&rdquo;</li>
  70. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Cheerios_effect">Cheerios effect</a>&rdquo;</li>
  71. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Lava_lamp">Lava lamp</a>&rdquo;</li>
  72. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Rayleigh%E2%80%93B%C3%A9nard_convection">Rayleigh–B&eacute;nard convection</a>&rdquo;</li>
  73. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Surface_tension">Surface tension</a>&rdquo;</li>
  74. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Plateau–Rayleigh_instability">Plateau–Rayleigh instability</a>&rdquo;</li>
  75. </ul>
  76. <p>
  77. Other readings:</p>
  78. <ul class="bullets">
  79. <li>&ldquo;<a target="_blank" href="https://books.google.com/books?id=MVIwAAAAIAAJ&pg=PA330&hl=en#v=onepage&q&f=false">On
  80. certain curious Motions observable at the Surfaces of Wine and other Alcoholic Liquors</a>,&rdquo;
  81. by James Thomson, in <em>The London, Edinburgh and Dublin Philosophical Magazine and Journal of Science,</em>
  82. p. 330</li>
  83. </ul>]]></description>
  84.         <dc:creator>Tom Sharp</dc:creator>
  85.         <link>http://sharpgiving.com/thebookofscience/items/p1855b.html</link>
  86.         <guid>http://sharpgiving.com/thebookofscience/items/p1855b.html#Thebookofscience1855b</guid>
  87.         <pubDate>Sat, 20 Jan 2018 12:00:00 GMT</pubDate>
  88.      </item>
  89.  
  90.  <item>
  91.         <title>1763 - "Bayes&rsquo; theorem"</title>
  92.         <description><![CDATA[<strong>Scientists:</strong> Thomas Bayes<br />
  93. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1763.html"><img
  94. style="margin-left:10px;vertical-align:top;width:100px;"
  95.  src="http://sharpgiving.com/thebookofscience/iimgs/i1763.png"
  96. alt="Bayes&rsquo; theorem" /></a><br />
  97. <h2>Bayes&rsquo; theorem</h2>
  98. <pre><font face="arial">Intuition disregards the base rate;
  99.     Bayes taught us to regard it.
  100.  
  101.     If you think about whether a mammogram
  102.          detects breast cancer,
  103.  
  104.     you must consider the base rate—
  105.          the prevalence of breast cancer.
  106.  
  107.          If a mammogram shows
  108.               you have breast cancer
  109.  
  110.          and the diagnosis is accurate
  111.               only 80 percent of the time
  112.  
  113.          but only one person in a hundred
  114.               gets breast cancer,
  115.  
  116.          then your chance of having it is
  117.               only about 7.8 percent.</font></pre>
  118. <p><a href="http://sharpgiving.com/thebookofscience/items/p1763.html"><em>More
  119. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  120. <h2 id="commentary">Commentary</h2>
  121. <p>It goes by the name of &ldquo;logic,&rdquo; but what we mean
  122. is trying to overcome our instinctual thought-processes
  123. to adhere more closely to reality.
  124. </p>
  125. <p>
  126. See also in <em>The book of science:</em></p>
  127. <ul class="bullets">
  128. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1654toc">1654</a>&mdash;<em><a
  129. href="http://sharpgiving.com/thebookofscience/items/p1654.html">Probability theory</a></em>&mdash;<a
  130. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Pascal">Blaise Pascal</a>,
  131. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=deFermat">Pierre de Fermat</a></li>
  132. </ul>
  133. <p>
  134. Readings on wikipedia:</p>
  135. <ul class="bullets">
  136. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Thomas_Bayes">Thomas Bayes</a>&rdquo;</li>
  137. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Richard_Price">Richard Price</a>&rdquo;</li>
  138. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Pierre-Simon_Laplace">Pierre-Simon Laplace</a>&rdquo;</li>
  139. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Bayes%27_theorem">Bayes&rsquo; theorem</a>&rdquo;</li>
  140. </ul>
  141. <p>
  142. Other readings:</p>
  143. <ul class="bullets">
  144. <li>&ldquo;<a target="_blank" href="https://betterexplained.com/articles/an-intuitive-and-short-explanation-of-bayes-theorem/">An Intuitive
  145. (and Short) Explanation of Bayes&rsquo; Theorem</a>,&rdquo; Better Explained</li>
  146. </ul>]]></description>
  147.         <dc:creator>Tom Sharp</dc:creator>
  148.         <link>http://sharpgiving.com/thebookofscience/items/p1763.html</link>
  149.         <guid>http://sharpgiving.com/thebookofscience/items/p1763.html#Thebookofscience1763</guid>
  150.         <pubDate>Sat, 13 Jan 2018 12:00:00 GMT</pubDate>
  151.      </item>
  152.  
  153.  <item>
  154.         <title>1913 - "Atomic battery"</title>
  155.         <description><![CDATA[<strong>Scientist:</strong> Henry Moseley<br />
  156. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1913d.html"><img
  157. style="margin-left:10px;vertical-align:top;width:100px;"
  158.  src="http://sharpgiving.com/thebookofscience/iimgs/i1913d.png"
  159. alt="Atomic battery" /></a><br />
  160. <h2>Atomic battery</h2>
  161. <pre><font face="arial">When radioactive isotopes decay,
  162. they produce thermal and kinetic energy
  163.  
  164. so that we can make an atomic battery
  165. using that energy to generate electricity.
  166.  
  167. Henry Moseley made first atomic battery
  168. using beta radiation from radium.</font></pre>
  169. <p><a href="http://sharpgiving.com/thebookofscience/items/p1913d.html"><em>More
  170. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  171. <h2 id="commentary">Commentary</h2>
  172. <p>By definition, a utopia does not veer toward a police state or dictatorship,
  173. and one is still entitled to one&rsquo;s ideals.
  174. </p>
  175. <p>The future of atomic energy is still on hold, however,
  176. while we exploit the potential of chemical energy.</p>
  177. <p>
  178. See also in <em>The book of science:</em></p>
  179. <ul class="bullets">
  180. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1896toc">1896</a>&mdash;<em><a
  181. href="http://sharpgiving.com/thebookofscience/items/p1896.html">Radioactivity</a></em>&mdash;<a
  182. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Becquerel">Henri Becquerel</a>,
  183. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=CurieM">Marie Curie</a>,
  184. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=CurieP">Pierre Curie</a>,
  185. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Rutherford">Ernest Rutherford</a>,
  186. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Hoffmann">Frederick Soddy</a></li>
  187. </ul>
  188. <p>
  189. Readings on wikipedia:</p>
  190. <ul class="bullets">
  191. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Henry_Moseley">Henry Moseley</a>&rdquo;</li>
  192. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Atomic_battery">Atomic battery</a>&rdquo;</li>
  193. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Betavoltaic_device">Betavoltaic device</a>&rdquo;</li>
  194. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Beta_decay">Beta decay</a>&rdquo;</li>
  195. </ul>]]></description>
  196.         <dc:creator>Tom Sharp</dc:creator>
  197.         <link>http://sharpgiving.com/thebookofscience/items/p1913d.html</link>
  198.         <guid>http://sharpgiving.com/thebookofscience/items/p1913d.html#Thebookofscience1913d</guid>
  199.         <pubDate>Sat, 06 Jan 2018 12:00:00 GMT</pubDate>
  200.      </item>
  201.  
  202.  <item>
  203.         <title>1907 - "Magnetic domain"</title>
  204.         <description><![CDATA[<strong>Scientist:</strong> Pierre Weiss<br />
  205. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1907d.html"><img
  206. style="margin-left:10px;vertical-align:top;width:100px;"
  207.  src="http://sharpgiving.com/thebookofscience/iimgs/i1907d.png"
  208. alt="Magnetic domain" /></a><br />
  209. <h2>Magnetic domain</h2>
  210. <pre><font face="arial">Pierre Weiss was the first to say
  211. atoms in a ferromagnetic material align
  212. in somewhat random groups called domains
  213. that contain a trillion or more atoms.
  214.  
  215. Weiss didn&rsquo;t say why.
  216.  
  217. When a material cools below its Curie temperature,
  218. each crystalline grain
  219. spontaneously divides into domains
  220. to reduce its magnetostatic energy.
  221.  
  222. It doesn&rsquo;t divide into too many domains
  223. because it takes energy to maintain the surfaces
  224. where domains of different orientations meet.
  225.  
  226. If the orientations of domains
  227. add up to greater than zero,
  228. the material is magnetized to some degree;
  229. otherwise, the domains balance to zero.</font></pre>
  230. <p><a href="http://sharpgiving.com/thebookofscience/items/p1907d.html"><em>More
  231. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  232. <h2 id="commentary">Commentary</h2>
  233. <p>The modern explanation of the magnetic domain is based on
  234. the effects of magnetostriction, and
  235. the &ldquo;exchange interaction&rdquo; of quantum theory,
  236. which we must leave for another day.
  237. </p>
  238. <p>
  239. See also in <em>The book of science:</em></p>
  240. <ul class="bullets">
  241. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1600toc">1600</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1600.html">Magnetism</a></em>&mdash;<a
  242. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Gilbert">William Gilbert</a></li>
  243. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1842btoc">1842</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1842b.html">Magnetostriction</a></em>&mdash;<a
  244. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Joule">James Prescott Joule</a></li>
  245. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1845btoc">1845-1913</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1845b.html">Magneto-optic and electro-optic effects</a></em>&mdash;<a
  246. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Faraday">Michael Faraday</a>,
  247. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Kerr">John Kerr</a>,
  248. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Cotton">Aim&eacute; Cotton</a>,
  249. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Voigt">Woldemar Voigt</a>,
  250. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Zeeman">Pieter Zeeman</a>,
  251. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Mouton">Henri Mouton</a>,
  252. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Stark">Johannes Stark</a>,
  253. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=LoSurdo">Antonino Lo Surdo</a></li>
  254. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1919toc">1919</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1919.html">Barkhausen effect</a></em>&mdash;<a
  255. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Barkhausen">Heinrich Barkhausen</a></li>
  256. </ul>
  257. <p>
  258. Readings on wikipedia:</p>
  259. <ul class="bullets">
  260. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Pierre_Weiss">Pierre Weiss</a>&rdquo;</li>
  261. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Magnetic_domain">Magnetic domain</a>&rdquo;</li>
  262. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Magnetic_moment">Magnetic moment</a>&rdquo;</li>
  263. </ul>]]></description>
  264.         <dc:creator>Tom Sharp</dc:creator>
  265.         <link>http://sharpgiving.com/thebookofscience/items/p1907d.html</link>
  266.         <guid>http://sharpgiving.com/thebookofscience/items/p1907d.html#Thebookofscience1907d</guid>
  267.         <pubDate>Sat, 30 Dec 2017 12:00:00 GMT</pubDate>
  268.      </item>
  269.  
  270.  <item>
  271.         <title>1919 - "Barkhausen effect"</title>
  272.         <description><![CDATA[<strong>Scientist:</strong> Heinrich Barkhausen<br />
  273. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1919.html"><img
  274. style="margin-left:10px;vertical-align:top;width:100px;"
  275.  src="http://sharpgiving.com/thebookofscience/iimgs/i1919.png"
  276. alt="Barkhausen effect" /></a><br />
  277. <h2>Barkhausen effect</h2>
  278. <pre><font face="arial">The quantum of magnetization in ferromagnetic material
  279. is not the atom with its two tiny poles
  280. but irregular bunches of atoms that align together called domains.
  281.  
  282. Heinrich Barkhausen found that changes of magnetization
  283. did not happen continuously, but in random steps
  284. as each magnetic domain resists being realigned
  285.  
  286. or is caught on defects in the crystal lattice,
  287. but then suddenly gives way, one after another,
  288. producing irregular avalanches of magnetic noise.</font></pre>
  289. <p><a href="http://sharpgiving.com/thebookofscience/items/p1919.html"><em>More
  290. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  291. <h2 id="commentary">Commentary</h2>
  292. <p>Magnetic domains are too small and too much alike to see without a Kerr microscope,
  293. and domains are not the same as crystalline grains in a metal,
  294. but wouldn&rsquo;t ancient makers of sword blades have had ideas
  295. about the alignments of iron crystals?
  296. </p>
  297. <p>
  298. See also in <em>The book of science:</em></p>
  299. <ul class="bullets">
  300. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1600toc">1600</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1600.html">Magnetism</a></em>&mdash;<a
  301. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Gilbert">William Gilbert</a></li>
  302. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1842btoc">1842</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1842b.html">Magnetostriction</a></em>&mdash;<a
  303. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Joule">James Prescott Joule</a></li>
  304. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1845btoc">1845-1913</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1845b.html">Magneto-optic and electro-optic effects</a></em>&mdash;<a
  305. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Faraday">Michael Faraday</a>,
  306. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Kerr">John Kerr</a>,
  307. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Cotton">Aim&eacute; Cotton</a>,
  308. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Voigt">Woldemar Voigt</a>,
  309. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Zeeman">Pieter Zeeman</a>,
  310. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Mouton">Henri Mouton</a>,
  311. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Stark">Johannes Stark</a>,
  312. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=LoSurdo">Antonino Lo Surdo</a></li>
  313. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1896dtoc">1896,1902</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1896d.html">Magnetic detector</a></em>&mdash;<a
  314. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Rutherford">Ernest Rutherford</a>,
  315. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Marconi">Guglielmo Marconi</a></li>
  316. </ul>
  317. <p>
  318. Readings on wikipedia:</p>
  319. <ul class="bullets">
  320. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Heinrich_Barkhausen">Heinrich Barkhausen</a>&rdquo;</li>
  321. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Barkhausen_effect">Barkhausen effect</a>&rdquo;</li>
  322. </ul>]]></description>
  323.         <dc:creator>Tom Sharp</dc:creator>
  324.         <link>http://sharpgiving.com/thebookofscience/items/p1919.html</link>
  325.         <guid>http://sharpgiving.com/thebookofscience/items/p1919.html#Thebookofscience1919</guid>
  326.         <pubDate>Sat, 23 Dec 2017 12:00:00 GMT</pubDate>
  327.      </item>
  328.  
  329.  <item>
  330.         <title>1905 - "Phased array"</title>
  331.         <description><![CDATA[<strong>Scientists:</strong> scientists?<br />
  332. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1905b.html"><img
  333. style="margin-left:10px;vertical-align:top;width:100px;"
  334.  src="http://sharpgiving.com/thebookofscience/iimgs/i1905b.png"
  335. alt="Phased array" /></a><br />
  336. <h2>Phased array</h2>
  337. <pre><font face="arial">A radio antenna broadcasts in all directions.
  338. Karl Ferdinand Braun showed that three vertical antennas
  339. placed at the points of an equilateral triangle
  340. and operated so that the signal from two is delayed
  341. by a quarter of a cycle relative to the third
  342. have a combined directional broadcast perpendicular
  343. to the two that operate in phase and away from the third.</font></pre>
  344. <p><a href="http://sharpgiving.com/thebookofscience/items/p1905b.html"><em>More
  345. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  346. <h2 id="commentary">Commentary</h2>
  347. <p>During the Cold War, my father worked at the USAF general surveillance radar station on Mount Tamalpais,
  348. which featured a large domed rotating radar antenna.
  349. Modern computers and phased array radar stations eventually made such stations obsolete.
  350. </p>
  351. <p>Sculling is when each rower has two oars; sweeping is when each rower has one oar.</p>
  352. <p>
  353. See also in <em>The book of science:</em></p>
  354. <ul class="bullets">
  355. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1896btoc">1896</a>&mdash;<em><a
  356. href="http://sharpgiving.com/thebookofscience/items/p1896b.html">Radio</a></em>&mdash;<a
  357. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Marconi">Guglielmo Marconi</a></li>
  358. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1904etoc">1904</a>&mdash;<em><a
  359. href="http://sharpgiving.com/thebookofscience/items/p1904e.html">Telemobiloscope</a></em>&mdash;<a
  360. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=H&uuml;lsmeyer">Christian H&uuml;lsmeyer</a></li>
  361. </ul>
  362. <p>
  363. Readings on wikipedia:</p>
  364. <ul class="bullets">
  365. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Karl_Ferdinand_Braun">Karl Ferdinand Braun</a>&rdquo;</li>
  366. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Phased_array">Phased array</a>&rdquo;</li>
  367. </ul>
  368. <p>
  369. Other readings:</p>
  370. <ul class="bullets">
  371. <li>&ldquo;<a target="_blank" href="http://www.nobelprize.org/nobel_prizes/physics/laureates/1909/braun-lecture.pdf">Electrical
  372. oscillations and wireless telegraphy, <em>Nobel Lecture, December 11, 1909,</em></a>&rdquo;
  373. by Karl Ferdinand Braun, pp. 238-241</li>
  374. </ul>]]></description>
  375.         <dc:creator>Tom Sharp</dc:creator>
  376.         <link>http://sharpgiving.com/thebookofscience/items/p1905b.html</link>
  377.         <guid>http://sharpgiving.com/thebookofscience/items/p1905b.html#Thebookofscience1905b</guid>
  378.         <pubDate>Sat, 16 Dec 2017 12:00:00 GMT</pubDate>
  379.      </item>
  380.  
  381.  <item>
  382.         <title>1874,1904 - "Crystal diode"</title>
  383.         <description><![CDATA[<strong>Scientists:</strong> scientists?<br />
  384. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1874.html"><img
  385. style="margin-left:10px;vertical-align:top;width:100px;"
  386.  src="http://sharpgiving.com/thebookofscience/iimgs/i1874.png"
  387. alt="Crystal diode" /></a><br />
  388. <h2>Crystal diode</h2>
  389. <pre><font face="arial">Karl Ferdinand Braun discovered
  390. unilateral conduction of crystals in 1874
  391. and patented a cat&rsquo;s-whisker crystal diode
  392. as a radio rectifier in 1899.
  393.  
  394. Braun found that the point of a wire
  395. that lightly touches a semiconducting crystal
  396. creates a junction that permits electrons
  397. to flow from the wire to the crystal
  398. but not from the crystal to the wire.
  399.  
  400. Around 1904, Henry Harrison Chase Dunwoody
  401. developed a cat&rsquo;s-whisker detector using carborundum,
  402. and Greenleaf Whittier Pickard developed
  403. a cat&rsquo;s-whisker detector using galena.</font></pre>
  404. <p><a href="http://sharpgiving.com/thebookofscience/items/p1874.html"><em>More
  405. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  406. <h2 id="commentary">Commentary</h2>
  407. <p>I made a radio in high school with a germanium crystal diode,
  408. and, using our garage door as an antenna,
  409. listened to the local AM station with an ear-bud.
  410. </p>
  411. <p>
  412. See also in <em>The book of science:</em></p>
  413. <ul class="bullets">
  414. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1902btoc">1902</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1902b.html">Hot wire barretter</a></em>&mdash;<a
  415. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  416. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1903ctoc">1903</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1903c.html">Electrolytic detector</a></em>&mdash;<a
  417. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  418. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1904htoc">1904</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1904h.html">Fleming valve</a></em>&mdash;<a
  419. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=FlemingJA">John Ambrose Fleming</a></li>
  420. </ul>
  421. <p>
  422. Readings on wikipedia:</p>
  423. <ul class="bullets">
  424. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Karl_Ferdinand_Braun">Karl Ferdinand Braun</a>&rdquo;</li>
  425. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Henry_Harrison_Chase_Dunwoody">Henry Harrison Chase Dunwoody</a>&rdquo;</li>
  426. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Greenleaf_Whittier_Pickard">Greenleaf Whittier Pickard</a>&rdquo;</li>
  427. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Diode">Diode</a>&rdquo;</li>
  428. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Rectifier">Rectifier</a>&rdquo;</li>
  429. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Cat%27s-whisker_detector">Cat&rsquo;s-whisker detector</a>&rdquo;</li>
  430. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Detector_(radio)">Detector (radio)</a>&rdquo;</li>
  431. </ul>]]></description>
  432.         <dc:creator>Tom Sharp</dc:creator>
  433.         <link>http://sharpgiving.com/thebookofscience/items/p1874.html</link>
  434.         <guid>http://sharpgiving.com/thebookofscience/items/p1874.html#Thebookofscience1874</guid>
  435.         <pubDate>Sat, 09 Dec 2017 12:00:00 GMT</pubDate>
  436.      </item>
  437.  
  438.  <item>
  439.         <title>1906-1912 - "Triode"</title>
  440.         <description><![CDATA[<strong>Scientists:</strong> Lee de Forest, Irving Langmuir<br />
  441. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1906d.html"><img
  442. style="margin-left:10px;vertical-align:top;width:100px;"
  443.  src="http://sharpgiving.com/thebookofscience/iimgs/i1906d.png"
  444. alt="Triode" /></a><br />
  445. <h2>Triode</h2>
  446. <pre><font face="arial"><b>Audion</b>
  447. Lee de Forest took a Fleming valve
  448. added a grid electrode between filament and plate.
  449.  
  450. He left a rarified gas in the tube,
  451. believing it was necessary for electrical conduction,
  452.  
  453. and wired it so a small current flowing to the grid
  454. controls a larger current flowing from the filament to the plate.
  455.  
  456. <b>Kenotron</b>
  457. Irving Langmuir built a Fleming diode with a complete vacuum
  458. and found it could rectify higher voltages.
  459.  
  460. <b>Pliotron</b>
  461. Irving Langmuir built an Audion with a complete vacuum
  462. and found it could amplify higher frequencies.</font></pre>
  463. <p><a href="http://sharpgiving.com/thebookofscience/items/p1906d.html"><em>More
  464. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  465. <h2 id="commentary">Commentary</h2>
  466. <p>Lee de Forest popularized the use of the term &ldquo;radio&rdquo; in place of &ldquo;wireless&rdquo;
  467. in the United States. In the British Commonwealth, the use of &ldquo;wireless&rdquo; meaning &ldquo;radio&rdquo;
  468. persisted longer.
  469. </p>
  470. <p>
  471. See also in <em>The book of science:</em></p>
  472. <ul class="bullets">
  473. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1903ctoc">1903</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1903c.html">Electrolytic detector</a></em>&mdash;<a
  474. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  475. <li><a href="http://sharpgiving.com/thebookofscience/toc.html?fragment=1904htoc">1904</a>&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1904h.html">Fleming valve</a></em>&mdash;<a
  476. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=FlemingJA">John Ambrose Fleming</a></li>
  477. </ul>
  478. <p>
  479. Readings on wikipedia:</p>
  480. <ul class="bullets">
  481. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Lee_de_Forest">Lee de Forest</a>&rdquo;</li>
  482. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Irving_Langmuir">Irving Langmuir</a>&rdquo;</li>
  483. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Triode">Triode</a>&rdquo;</li>
  484. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Audion">Audion</a>&rdquo;</li>
  485. </ul>]]></description>
  486.         <dc:creator>Tom Sharp</dc:creator>
  487.         <link>http://sharpgiving.com/thebookofscience/items/p1906d.html</link>
  488.         <guid>http://sharpgiving.com/thebookofscience/items/p1906d.html#Thebookofscience1906d</guid>
  489.         <pubDate>Sat, 02 Dec 2017 12:01:00 GMT</pubDate>
  490.      </item>
  491.  
  492.  <item>
  493.         <title>1904 - "Fleming valve"</title>
  494.         <description><![CDATA[<strong>Scientist:</strong> John Ambrose Fleming<br />
  495. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1904h.html"><img
  496. style="margin-left:10px;vertical-align:top;width:100px;"
  497.  src="http://sharpgiving.com/thebookofscience/iimgs/i1904h.png"
  498. alt="Fleming valve" /></a><br />
  499. <h2>Fleming valve</h2>
  500. <pre><font face="arial">John Ambrose Fleming designed the transmitter
  501. that Marconi used for the first transmission
  502. across the Atlantic; however, Fleming
  503. was not satisfied with the receiver,
  504. which used a coherer to detect the radio signal.
  505.  
  506. Fleming had worked for Thomas Edison
  507. and knew of the Edison effect, and so
  508. he replaced the coherer with an Edison-effect bulb,
  509. which rectified high-frequency oscillations
  510. to let a galvanometer detect dots and dashes.</font></pre>
  511. <p><a href="http://sharpgiving.com/thebookofscience/items/p1904h.html"><em>More
  512. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  513. <h2 id="commentary">Commentary</h2>
  514. <p>Morse code signals oscillated too fast for a galvanometer to detect them,
  515. but a galvanometer was able to show tiny direct-current pulses from a Fleming value.</p>
  516. <p>Fleming is the originator of the left-hand rule for electric motors,
  517. and the right-hand rule for electric generators.
  518. </p>
  519. <p>
  520. See also in <em>The book of science:</em></p>
  521. <ul class="bullets">
  522. <li>1857&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1857.html">Geissler tube</a></em>&mdash;<a
  523. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Geissler">Heinrich Geissler</a></li>
  524. <li>1869&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1869b.html">Cathode ray</a></em>&mdash;<a
  525. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Hittorf">Johann Wilhelm Hittorf</a></li>
  526. <li>1869-1875&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1869c.html">Crookes tube</a></em>&mdash;<a
  527. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Crookes">William Crookes</a></li>
  528. <li>1873,1880&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1873c.html">Thermionic emission</a></em>&mdash;<a
  529. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Guthrie">Frederick Guthrie</a>,
  530. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Edison">Thomas Edison</a></li>
  531. <li>1890&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1890d.html">Coherer</a></em>&mdash;<a
  532. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Branly">Edouard Branly</a></li>
  533. <li>1896&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1896b.html">Radio</a></em>&mdash;<a
  534. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Marconi">Guglielmo Marconi</a></li>
  535. <li>1896,1902&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1896d.html">Magnetic detector</a></em>&mdash;<a
  536. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Rutherford">Ernest Rutherford</a>,
  537. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Marconi">Guglielmo Marconi</a></li>
  538. </ul>
  539. <p>
  540. Readings on wikipedia:</p>
  541. <ul class="bullets">
  542. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/John_Ambrose_Fleming">John Ambrose Fleming</a>&rdquo;</li>
  543. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Fleming_valve">Fleming valve</a>&rdquo;</li>
  544. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Detector_(radio)">Detector (radio)</a>&rdquo;</li>
  545. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Rectifier">Rectifier</a>&rdquo;</li>
  546. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Diode">Diode</a>&rdquo;</li>
  547. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Ignitron">Ignitron</a>&rdquo;</li>
  548. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Trigatron">Trigatron</a>&rdquo;</li>
  549. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Thyratron">Thyratron</a>&rdquo;</li>
  550. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Thyristor">Thyristor</a>&rdquo;</li>
  551. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Krytron">Krytron</a>&rdquo;</li>
  552. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Klystron">Klystron</a>&rdquo;</li>
  553. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Fleming%27s_left-hand_rule_for_motors">Fleming&rsquo;s left-hand rule for motors</a>&rdquo;</li>
  554. </ul>
  555. <p>
  556. Other readings:</p>
  557. <ul class="bullets">
  558. <li>&ldquo;<a target="_blank" href="http://ethw.org/Milestones:Fleming_Valve,_1904">Milestones: Fleming Valve, 1904</a>,&rdquo;
  559. Engineering and Technology History Wiki</li>
  560. </ul>]]></description>
  561.         <dc:creator>Tom Sharp</dc:creator>
  562.         <link>http://sharpgiving.com/thebookofscience/items/p1904h.html</link>
  563.         <guid>http://sharpgiving.com/thebookofscience/items/p1904h.html#Thebookofscience1904h</guid>
  564.         <pubDate>Sat, 25 Nov 2017 12:00:00 GMT</pubDate>
  565.      </item>
  566.  
  567.  <item>
  568.         <title>1906 - "AM broadcasting"</title>
  569.         <description><![CDATA[<strong>Scientist:</strong> Reginald Fessenden<br />
  570. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1906c.html"><img
  571. style="margin-left:10px;vertical-align:top;width:100px;"
  572.  src="http://sharpgiving.com/thebookofscience/iimgs/i1906c.png"
  573. alt="AM broadcasting" /></a><br />
  574. <h2>DiscAM broadcastingovery</h2>
  575. <pre><font face="arial">Reginald Fessenden&rsquo;s first AM transmission
  576. in December 1900 used a carbon microphone in series
  577. with a rotary spark-gap transmitter
  578. producing ten thousand sparks per second,
  579. but the spark-gap transmitter was too noisy
  580. and too spread out over over the frequency band
  581. to carry clear voice transmissions,
  582. and the Branly or Marconi coherer
  583. was too crude to demodulate a voice frequency.
  584.  
  585. So Fessenden began to work to improve
  586. both the transmitter and the receiver.
  587. He invented the process of heterodyning
  588. to modulate and demodulate an AM signal.
  589. He invented the hot wire barretter and various
  590. electrolytic detectors to rectify the received signal.
  591. He contracted with GE for the Alexanderson alternator
  592. to produce a high frequency radio carrier signal.</font></pre>
  593. <p><a href="http://sharpgiving.com/thebookofscience/items/p1906c.html"><em>More
  594. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  595. <h2 id="commentary">Commentary</h2>
  596. <p>Services such as Twitter and Facebook, broadcasting to cell phones (wireless telephones),
  597. complete the circle that began with the development of radio as a broadcast media.
  598. </p>
  599. <p>
  600. See also in <em>The book of science:</em></p>
  601. <ul class="bullets">
  602. <li>1901&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1901b.html">Heterodyne</a></em>&mdash;<a
  603. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  604. <li>1902&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1902b.html">Hot wire barretter</a></em>&mdash;<a
  605. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  606. <li>1903&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1903c.html">Electrolytic detector</a></em>&mdash;<a
  607. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  608. <li>1904&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1904f.html">Alexanderson alternator</a></em>&mdash;<a
  609. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Alexanderson">Ernst Alexanderson</a></li>
  610. <!--li>1904&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1904h.html">Fleming valve</a></em>&mdash;<a
  611. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=FlemingJA">John Ambrose Fleming</a></li-->
  612. <!-- li>1906&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1906c.html">AM broadcasting</a></em>&mdash;<a
  613. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li -->
  614. </ul>
  615. <p>
  616. Readings on wikipedia:</p>
  617. <ul class="bullets">
  618. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Reginald_Fessenden">Reginald Fessenden</a>&rdquo;</li>
  619. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/AM_broadcasting">AM broadcasting</a>&rdquo;</li>
  620. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Amplitude_modulation">Amplitude modulation</a>&rdquo;</li>
  621. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Radiotelephone">Radiotelephone</a>&rdquo;</li>
  622. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Voice_frequency">Voice frequency</a>&rdquo;</li>
  623. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Spark-gap_transmitter">Spark-gap transmitter</a>&rdquo;</li>
  624. </ul>
  625. <p>
  626. Other readings:</p>
  627. <ul class="bullets">
  628. <li>&ldquo;<a target="_blank" href="https://archive.org/stream/EarlyRadioWaveDetectors/Phillips-EarlyRadioWaveDetectors">Early
  629. radio wave detectors</a>,&rdquo; by Vivian J. Phillips</li>
  630. <li><a target="_blank" href="http://ethw.org/Milestones:First_Wireless_Radio_Broadcast_by_Reginald_A._Fessenden,_1906#First_Wireless_Radio_Broadcast_by_Reginald_A._Fessenden.2C_1906">IEEE
  631. Milestone: First Wireless Radio Broadcast by Reginald A. Fessenden, 1906</a>:
  632. <ul class="bullets">
  633. <li>January 1906: Rotary-spark transmitter and first two-way transatlantic transmission</li>
  634. <li>21 December 1906: Alternator-transmitter used for wireless telephony</li>
  635. <li>24 December 1906: Alternator-transmitter used for
  636. <a target="_blank" href="http://ethw.org/Fessenden%27s_Christmas_Eve_Broadcast">Fessenden&rsquo;s Christmas Eve broadcast</a> to ships at sea
  637. of voice and music</li>
  638. </ul></li>
  639. </ul>]]></description>
  640.         <dc:creator>Tom Sharp</dc:creator>
  641.         <link>http://sharpgiving.com/thebookofscience/items/p1906c.html</link>
  642.         <guid>http://sharpgiving.com/thebookofscience/items/p1906c.html#Thebookofscience1906c</guid>
  643.         <pubDate>Sat, 18 Nov 2017 12:00:00 GMT</pubDate>
  644.      </item>
  645.  
  646.  <item>
  647.         <title>1904 - "Alexanderson alternator"</title>
  648.         <description><![CDATA[<strong>Scientist:</strong> Ernst Alexanderson<br />
  649. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1904f.html"><img
  650. style="margin-left:10px;vertical-align:top;width:100px;"
  651.  src="http://sharpgiving.com/thebookofscience/iimgs/i1904f.png"
  652. alt="Alexanderson alternator" /></a><br />
  653. <h2>Alexanderson alternator</h2>
  654. <pre><font face="arial">Before 1904, many inventors, including Nikola Tesla,
  655. created an alternator to generate an electromagnetic frequency,
  656. but none of these produced a frequency high enough
  657. for radio transmission; they were all under twenty kilohertz.
  658.  
  659. However, in 1904, Reginald Fessenden, working for
  660. National Electric Signaling Company, contracted with GE
  661. for an alternator to produce up to a hundred kilohertz
  662. for continuous wave radio transmission.
  663.  
  664. Ernst Alexanderson designed an alternator whose frequency
  665. was controlled by a rotor with hundreds of narrow slots
  666. that caused a variable reluctance to interrupt the flux,
  667. which induced a radio-frequency voltage in a set of coils.</font></pre>
  668. <p><a href="http://sharpgiving.com/thebookofscience/items/p1904f.html"><em>More
  669. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  670. <h2 id="commentary">Commentary</h2>
  671. <p>In 1903, Charles Proteus Steinmetz of GE delivered a ten-kilohertz alternator-transmitter,
  672. which Fessenden could not use as a radio transmitter.
  673. Ernst Alexanderson&rsquo;s effort was far more successful;
  674. however, alternator-transmitters were eventually replaced by vacuum-tube transmitters.
  675. </p>
  676. <p>
  677. See also in <em>The book of science:</em></p>
  678. <ul class="bullets">
  679. <li>1901&mdash;<em><a href="http://sharpgiving.com/thebookofscience/itemsp1901b.html">Heterodyne</a></em>&mdash;<a
  680. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  681. <li>1902&mdash;<em><a href="http://sharpgiving.com/thebookofscience/itemsp1902b.html">Hot wire barretter</a></em>&mdash;<a
  682. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  683. <li>1903&mdash;<em><a href="http://sharpgiving.com/thebookofscience/itemsp1903c.html">Electrolytic detector</a></em>&mdash;<a
  684. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  685. </ul>
  686. <p>
  687. Readings on wikipedia:</p>
  688. <ul class="bullets">
  689. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Ernst_Alexanderson">Ernst Alexanderson</a>&rdquo;</li>
  690. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Alexanderson_alternator">Alexanderson alternator</a>&rdquo;</li>
  691. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Alexanderson_Day">Alexanderson Day</a>&rdquo;</li>
  692. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Varberg_Radio_Station">Varberg Radio Station</a>&rdquo;</li>
  693. </ul>
  694. <p>
  695. Other readings:</p>
  696. <ul class="bullets">
  697. <li>&ldquo;<a target="_blank" href="http://earlyradiohistory.us/1920alt.htm">Transoceanic Radio Communication</a>,&rdquo;
  698. by E. F. W. Alexanderson, <em>General Electric Review,</em> October 1920, pages 794-797</li>
  699. </ul>]]></description>
  700.         <dc:creator>Tom Sharp</dc:creator>
  701.         <link>http://sharpgiving.com/thebookofscience/items/p1904f.html</link>
  702.         <guid>http://sharpgiving.com/thebookofscience/items/p1904f.html#Thebookofscience1904f</guid>
  703.         <pubDate>Sat, 11 Nov 2017 12:00:00 GMT</pubDate>
  704.      </item>
  705.  
  706.  <item>
  707.         <title>1903 - "Electrolytic detector"</title>
  708.         <description><![CDATA[<strong>Scientist:</strong> Reginald Fessenden<br />
  709. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1903c.html"><img
  710. style="margin-left:10px;vertical-align:top;width:100px;"
  711.  src="http://sharpgiving.com/thebookofscience/iimgs/i1903c.png"
  712. alt="Electrolytic detector" /></a><br />
  713. <h2>Electrolytic detector</h2>
  714. <pre><font face="arial">Radio receivers from 1903
  715.     until 1913 used
  716. Reginald Fessenden&rsquo;s bare-point
  717.     electrolytic detector
  718. to convert radio waves
  719.     to pulsed direct-current signals
  720. capable of receiving either
  721.     Morse code or AM signals.</font></pre>
  722. <p><a href="http://sharpgiving.com/thebookofscience/items/p1903c.html"><em>More
  723. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  724. <h2 id="commentary">Commentary</h2>
  725. <p>Other people such as  Michael I. Pupin, W. Schloemilch, and Hugo Gernsback
  726. have also been given credit for the discovery of this device; however,
  727. Reginald Fessenden, who was also responsible for the development of AM radio,
  728. was the first to put it to use. The electrolytic detector was sometimes called
  729. the Schl&ouml;milch cell, the Ferri&eacute; cell, or the Fessenden cell.
  730. </p>
  731. <p>
  732. See also in <em>The book of science:</em></p>
  733. <ul class="bullets">
  734. <li>1890&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1890d.html">Coherer</a></em>&mdash;<a
  735. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Branly">Edouard Branly</a></li>
  736. <li>1896&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1896b.html">Radio</a></em>&mdash;<a
  737. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Marconi">Guglielmo Marconi</a></li>
  738. <li>1896,1902&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1896d.html">Magnetic detector</a></em>&mdash;<a
  739. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Rutherford">Ernest Rutherford</a>,
  740. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Marconi">Guglielmo Marconi</a></li>
  741. <li>1901&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1901b.html">Heterodyne</a></em>&mdash;<a
  742. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  743. <li>1902&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1902b.html">Hot wire barretter</a></em>&mdash;<a
  744. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  745. </ul>
  746. <p>
  747. Readings on wikipedia:</p>
  748. <ul class="bullets">
  749. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Reginald_Fessenden">Reginald Fessenden</a>&rdquo;</li>
  750. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Electrolytic_detector">Electrolytic detector</a>&rdquo;</li>
  751. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Detector_(radio)">Detector (radio)</a>&rdquo;</li>
  752. </ul>
  753. <p>
  754. Other readings:</p>
  755. <ul class="bullets">
  756. <li>&ldquo;<a target="_blank" href="http://www.snopes.com/radiotv/tv/fillings.asp">Brace Yourself:
  757. Did radio transmissions picked up by Lucille Ball&rsquo;s fillings lead to the capture of a Japanese spy?</a>&rdquo;
  758. Snopes.com</li>
  759. </ul>]]></description>
  760.         <dc:creator>Tom Sharp</dc:creator>
  761.         <link>http://sharpgiving.com/thebookofscience/items/p1903c.html</link>
  762.         <guid>http://sharpgiving.com/thebookofscience/items/p1903c.html#Thebookofscience1903c</guid>
  763.         <pubDate>Sat, 04 Nov 2017 12:00:00 GMT</pubDate>
  764.      </item>
  765.  
  766.  <item>
  767.         <title>1896,1902 - "Magnetic detector"</title>
  768.         <description><![CDATA[<strong>Scientists:</strong> Ernest Rutherford, Guglielmo Marconi<br />
  769. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1896d.html"><img
  770. style="margin-left:10px;vertical-align:top;width:100px;"
  771.  src="http://sharpgiving.com/thebookofscience/iimgs/i1896d.png"
  772. alt="Magnetic detector" /></a><br />
  773. <h2>Magnetic detector</h2>
  774. <pre><font face="arial">Ernest Rutherford made a device
  775. that detected Herzian waves based on the principle
  776. that an alternating current of decreasing amplitude
  777. demagnetizes iron.
  778.  
  779. He placed a bundle of magnetized iron wires
  780. in a coil attached to a Hertzian receiver.
  781. He determined loss of magnetization
  782. with a small magnet suspended near the bundle.</font></pre>
  783. <p><a href="http://sharpgiving.com/thebookofscience/items/p1896d.html"><em>More
  784. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  785. <h2 id="commentary">Commentary</h2>
  786. <p>This field of research is richer with branches than the final results might have suggested.
  787. These magnetic detectors, like the coherer, worked only for detecting the presence
  788. of damped-wave Morse-code transmissions
  789. (where the transmitter was turned on briefly for sending a dot
  790. and a bit longer for sending a dash),
  791. and were made obsolete by continuous-wave transmission for AM radio.
  792. </p>
  793. <p>
  794. See also in <em>The book of science:</em></p>
  795. <ul class="bullets">
  796. <li>1890&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1890d.html">Coherer</a></em>&mdash;<a
  797. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Branly">Edouard Branly</a></li>
  798. <li>1896&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1896b.html">Radio</a></em>&mdash;<a
  799. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Marconi">Guglielmo Marconi</a></li>
  800. <li>1902&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1902b.html">Hot wire barretter</a></em>&mdash;<a
  801. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  802. </ul>
  803. <p>
  804. Readings on wikipedia:</p>
  805. <ul class="bullets">
  806. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Ernest_Rutherford">Ernest Rutherford</a>&rdquo;</li>
  807. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Guglielmo_Marconi">Guglielmo Marconi</a>&rdquo;</li>
  808. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Magnetic_detector">Magnetic detector</a>&rdquo;</li>
  809. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Damped_wave">Damped wave</a>&rdquo;</li>
  810. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Hysteresis">Hysteresis</a>&rdquo;</li>
  811. </ul>
  812. <p>
  813. Other readings:</p>
  814. <ul class="bullets">
  815. <li>&ldquo;<a target="_blank" href="https://archive.org/stream/EarlyRadioWaveDetectors/Phillips-EarlyRadioWaveDetectors">Early
  816. radio wave detectors</a>,&rdquo; by Vivian J. Phillips</li>
  817. </ul>]]></description>
  818.         <dc:creator>Tom Sharp</dc:creator>
  819.         <link>http://sharpgiving.com/thebookofscience/items/p1896d.html</link>
  820.         <guid>http://sharpgiving.com/thebookofscience/items/p1896d.html#Thebookofscience1896d</guid>
  821.         <pubDate>Sat, 28 Oct 2017 12:00:00 GMT</pubDate>
  822.      </item>
  823.  
  824.  <item>
  825.         <title>1902 - "Hot wire barretter"</title>
  826.         <description><![CDATA[<strong>Scientist:</strong> Reginald Fessenden<br />
  827. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1902b.html"><img
  828. style="margin-left:10px;vertical-align:top;width:100px;"
  829.  src="http://sharpgiving.com/thebookofscience/iimgs/i1902b.png"
  830. alt="Hot wire barretter" /></a><br />
  831. <h2>Hot wire barretter</h2>
  832. <pre><font face="arial">For receiving AM radio signals,
  833. Reginald Fessenden ran a current
  834.     across a thin platinum wire
  835. heating it almost to the point
  836.     where it lost its ability to conduct.
  837.  
  838. Adding an AM signal to the current
  839. increased the temperature when the amplitude rose
  840.     stopping the flow of electricity
  841. and decreased the temperature when the amplitude fell
  842.     letting the electricity flow.</font></pre>
  843. <p><a href="http://sharpgiving.com/thebookofscience/items/p1902b.html"><em>More
  844. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  845. <h2 id="commentary">Commentary</h2>
  846. <p>Humphry Davy had discovered thermoresistance in 1821.
  847. It took a while for a practical use to be found for the effect.
  848. </p>
  849. <p>
  850. See also in <em>The book of science:</em></p>
  851. <ul class="bullets">
  852. <li>1821&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1821a.html">Electric conductivity</a></em>&mdash;<a
  853. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Davy">Humphry Davy</a>,
  854. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Cavendish">Henry Cavendish</a></li>
  855. <li>1873,1880&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1873c.html">Thermionic emission</a></em>&mdash;<a
  856. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Guthrie">Frederick Guthrie</a>,
  857. <a href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Edison">Thomas Edison</a></li>
  858. <li>1890&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1890d.html">Coherer</a></em>&mdash;<a
  859. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Branly">Edouard Branly</a></li>
  860. <li>1896&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1896b.html">Radio</a></em>&mdash;<a
  861. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Marconi">Guglielmo Marconi</a></li>
  862. <li>1901&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1901b.html">Heterodyne</a></em>&mdash;<a
  863. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Fessenden">Reginald Fessenden</a></li>
  864. </ul>
  865. <p>
  866. Readings on wikipedia:</p>
  867. <ul class="bullets">
  868. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Reginald_Fessenden">Reginald Fessenden</a>&rdquo;</li>
  869. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Hot_wire_barretter">Hot wire barretter</a>&rdquo;</li>
  870. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Detector_(radio)">Detector (radio)</a>&rdquo;</li>
  871. </ul>]]></description>
  872.         <dc:creator>Tom Sharp</dc:creator>
  873.         <link>http://sharpgiving.com/thebookofscience/items/p1902b.html</link>
  874.         <guid>http://sharpgiving.com/thebookofscience/items/p1902b.html#Thebookofscience1902b</guid>
  875.         <pubDate>Sat, 21 Oct 2017 12:00:00 GMT</pubDate>
  876.      </item>
  877.  
  878.  <item>
  879.         <title>1901 - "Heterodyne"</title>
  880.         <description><![CDATA[<strong>Scientist:</strong> Reginald Fessenden<br />
  881. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1901b.html"><img
  882. style="margin-left:10px;vertical-align:top;width:100px;"
  883.  src="http://sharpgiving.com/thebookofscience/iimgs/i1901b.png"
  884. alt="Heterodyne" /></a><br />
  885. <h2>Heterodyne</h2>
  886. <pre><font face="arial">To broadcast Morse code signals, a radio wave
  887. is turned on for different intervals to signify dashes and dots.
  888. However, to broadcast voice or music
  889. the signal must modify a continuous radio wave.
  890.  
  891. Amplitude modulation of a radio frequency
  892. requires shifting the message frequency and combining it
  893. with the frequency of the continuous radio wave.
  894. This process is called <em>heterodyning.</em>
  895.  
  896. For transmitting, the message frequency
  897. is combined with the carrier frequency;
  898. for receiving, the carrier frequency is subtracted from the signal
  899. resulting in a message shifted to the audio range.</font></pre>
  900. <p><a href="http://sharpgiving.com/thebookofscience/items/p1901b.html"><em>More
  901. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  902. <h2 id="commentary">Commentary</h2>
  903. <p>Heterodyne detection could reveal communication broadcasts from outer space
  904. from a ancient, superior, alien race of beings, if, that is, such a race, and such broadcasts
  905. were to be sent within the range of our receivers.
  906. The universe produces a lot of noise. Heterodyne processing of the noise itself
  907. can reveal both random and non-random processes.
  908. </p>
  909. <p>
  910. See also in <em>The book of science:</em></p>
  911. <ul class="bullets">
  912. <li>1896&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1896b.html">Radio</a></em>&mdash;<a
  913. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Marconi">Guglielmo Marconi</a></li>
  914. </ul>
  915. <p>
  916. Readings on wikipedia:</p>
  917. <ul class="bullets">
  918. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Reginald_Fessenden">Reginald Fessenden</a>&rdquo;</li>
  919. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Heterodyne">Heterodyne</a>&rdquo;</li>
  920. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Superheterodyne_receiver">Superheterodyne receiver</a>&rdquo;</li>
  921. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Heterodyne_detection">Heterodyne detection</a>&rdquo;</li>
  922. </ul>]]></description>
  923.         <dc:creator>Tom Sharp</dc:creator>
  924.         <link>http://sharpgiving.com/thebookofscience/items/p1901b.html</link>
  925.         <guid>http://sharpgiving.com/thebookofscience/items/p1901b.html#Thebookofscience1901b</guid>
  926.         <pubDate>Sat, 14 Oct 2017 12:00:00 GMT</pubDate>
  927.      </item>
  928.  
  929.  <item>
  930.         <title>1890 - "Coherer"</title>
  931.         <description><![CDATA[<strong>Scientist:</strong> Edouard Branly<br />
  932. <a target="_blank" href="http://sharpgiving.com/thebookofscience/items/p1890d.html"><img
  933. style="margin-left:10px;vertical-align:top;width:100px;"
  934.  src="http://sharpgiving.com/thebookofscience/iimgs/i1890d.png"
  935. alt="Coherer" /></a><br />
  936. <h2>Coherer</h2>
  937. <pre><font face="arial">They called them Hertzian waves
  938.     because Heinrich Hertz had discovered them
  939.          and Marconi had not yet invented the radio.
  940.  
  941. Edouard Branly was experimenting to see the effects
  942.     of electrical charges and sparks on metal filings,
  943.          and began to make devices containing metal filings
  944.               to detect the presence of electric waves.
  945.  
  946. By 1894 people including Oliver Lodge were making
  947.     their Branly coherers to detect Hertzian waves.</font></pre>
  948. <p><a href="http://sharpgiving.com/thebookofscience/items/p1890d.html"><em>More
  949. poems</em></a>&nbsp;.&nbsp;.&nbsp;.</p>
  950. <h2 id="commentary">Commentary</h2>
  951. <p>In radios, the coherer was replaced by the electrolytic detector, the crystal diode,
  952. and vacuum tubes such as the Fleming valve.
  953. </p>
  954. <p>The French term <em>particules</em> denotes a small element of a body.</p>
  955. <p>
  956. See also in <em>The book of science:</em></p>
  957. <ul class="bullets">
  958. <li>1896&mdash;<em><a href="http://sharpgiving.com/thebookofscience/items/p1896b.html">Radio</a></em>&mdash;<a
  959. href="http://sharpgiving.com/thebookofscience/byscientist.html?fragment=Marconi">Guglielmo Marconi</a></li>
  960. </ul>
  961. <p>
  962. Readings on wikipedia:</p>
  963. <ul class="bullets">
  964. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Edouard_Branly">Edouard Branly</a>&rdquo;</li>
  965. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Edouard_Branly">Temistocle Calzecchi-Onesti</a>&rdquo;</li>
  966. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Coherer">Coherer</a>&rdquo;</li>
  967. <li>&ldquo;<a target="_blank" href="http://wikipedia.org/wiki/Radio_receiver">Radio receiver</a>&rdquo;</li>
  968. </ul>]]></description>
  969.         <dc:creator>Tom Sharp</dc:creator>
  970.         <link>http://sharpgiving.com/thebookofscience/items/p1890d.html</link>
  971.         <guid>http://sharpgiving.com/thebookofscience/items/p1890d.html#Thebookofscience1890d</guid>
  972.         <pubDate>Sat, 14 Oct 2017 12:00:00 GMT</pubDate>
  973.      </item>
  974.  
  975.   </channel>
  976. </rss>
  977.  
Copyright © 2002-9 Sam Ruby, Mark Pilgrim, Joseph Walton, and Phil Ringnalda