{"id":18062,"date":"2026-10-16T13:56:58","date_gmt":"2026-10-16T12:56:58","guid":{"rendered":"https:\/\/www.socasailing.org.uk\/?p=18062"},"modified":"2026-10-16T14:01:18","modified_gmt":"2026-10-16T13:01:18","slug":"november-2026-jeremy-batch","status":"publish","type":"post","link":"https:\/\/www.socasailing.org.uk\/?p=18062","title":{"rendered":"November 2026 Jeremy Batch"},"content":{"rendered":"\n

Slightly pear-shaped: Measuring, Surveying and Mapping the World, part 2<\/strong><\/p>\n\n\n\n

That the Earth is round had been known for centuries; that it\u00a0 might also be (very) slightly oval was long-suspected, although we disagreed with the French as to which way the oval went.<\/p>\n

In this sequel to Jeremy\u2019s talk last year, we look in more detail\u00a0at the early British and French-led projects to create accurate maps and charts. \u00a0In Britain, William Roy\u2019s 1747 Survey of the Scottish Highlands would lead to the commencement, in 1791, of our nationwide Ordnance Survey. \u00a0Meanwhile, the French had been busy with\u00a0an even more ambitious project (begun in 1683) to measure their own prime meridian, not just through Paris and across France but around a quarter of the globe.<\/p>\n

If points had been awarded for effort, their meridian would have prevailed over ours, but the unit they redefined in the process (originally the length of a seconds pendulum, but now intended to be one ten-millionth of the length they were measuring) is now \u2014 for better or worse \u2014 used around most of the world.<\/p>\n\n\n

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The Greenwich and Paris meridians were linked across the Channel in 1787\u00a0using rival surveying instruments, both accurate to one arc-second (one sixtieth of one sixtieth of a degree). \u00a0Each\u00a0side swore their design was better (you can still see one of ours, made by Jesse Ramsden, in the Science Museum) but both gave\u00a0positioning errors of only 7 inches (oh, alright, 18 centimetres).<\/p>\n

Plus: why NATO compasses are divided into 6,400 degrees and why, if you capture a Russian field gun, you really need to watch which way you point it.<\/p>\n\n\n

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Slightly pear-shaped: Measuring, Surveying and Mapping the World, part 2 That the Earth is round had been known for centuries; that it\u00a0 might also be (very) slightly oval was long-suspected, although we disagreed with the French as to which way … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":15274,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-18062","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorised"],"_links":{"self":[{"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=\/wp\/v2\/posts\/18062","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=18062"}],"version-history":[{"count":3,"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=\/wp\/v2\/posts\/18062\/revisions"}],"predecessor-version":[{"id":18109,"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=\/wp\/v2\/posts\/18062\/revisions\/18109"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=\/wp\/v2\/media\/15274"}],"wp:attachment":[{"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=18062"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=18062"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.socasailing.org.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=18062"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}