Today, being in Dublin, I went on a little day trip to the charming seaside town of Dun Laoghaire (when you say it out loud, it sounds like “Dun Leary” — don’t ask). While there, I had a splendid time exploring the National Maritime Museum of Ireland.<\/p>\n
I learned all sorts of things today about sailing, lighthouses, engine technology, nautical charts, shipwrecks, lifeboats, sextants, trade routes, and many other fascinating topics, far too numerous to list here.<\/p>\n
But one fact in particular really stuck with me: In their hay day, every lighthouse flashed at a unique rate. That is, the motor that spun the light around was set to a different rate of rotation for every lighthouse.<\/p>\n
And the reason for this was simple and ingenious: If your ship was lost out at sea, and all you had to navigate by was the faint pulse of a distant lighthouse, you could time that pulse and you would know where you were.<\/p>\n
This concept is also the basis for heterodyning<\/i>, the core technology behind broadcast radio and television — a more recent innovation whereby multiple signals can be distinguished by their differing carrier frequencies.<\/p>\n
What I love about the pulse frequency scheme for identifying lighthouses is the way it shows that people are not getting more clever over time. People were always<\/i> clever. It’s just that, at various times in history, they have access to different technologies for showing how clever they can be.<\/p>\n","protected":false},"excerpt":{"rendered":"
Today, being in Dublin, I went on a little day trip to the charming seaside town of Dun Laoghaire (when you say it out loud, it sounds like “Dun Leary” — don’t ask). While there, I had a splendid time exploring the National Maritime Museum of Ireland. I learned all sorts of things today about … Continue reading “Lighthouses”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"http:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/16088"}],"collection":[{"href":"http:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=16088"}],"version-history":[{"count":1,"href":"http:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/16088\/revisions"}],"predecessor-version":[{"id":16089,"href":"http:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/16088\/revisions\/16089"}],"wp:attachment":[{"href":"http:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=16088"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=16088"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=16088"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}