1.0Museum of Angra do Heroismohttps://museu-angra.cultura.azores.gov.pt/en/Vitor Oliveirahttps://museu-angra.cultura.azores.gov.pt/en/author/vitor-oliveira/rich600338<blockquote class="wp-embedded-content" data-secret="blZuf7OKDB"><a href="https://museu-angra.cultura.azores.gov.pt/en/others/historical-pieces/lucas-signal-lantern/">“Lucas” Signal Lantern</a></blockquote><iframe sandbox="allow-scripts" security="restricted" src="https://museu-angra.cultura.azores.gov.pt/en/others/historical-pieces/lucas-signal-lantern/embed/#?secret=blZuf7OKDB" width="600" height="338" title="““Lucas” Signal Lantern” — Museum of Angra do Heroismo" data-secret="blZuf7OKDB" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe><script type="text/javascript"> /* <![CDATA[ */ /*! This file is auto-generated */ !function(d,l){"use strict";l.querySelector&&d.addEventListener&&"undefined"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!/[^a-zA-Z0-9]/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),o=l.querySelectorAll('blockquote[data-secret="'+t.secret+'"]'),c=new RegExp("^https?:$","i"),i=0;i<o.length;i++)o[i].style.display="none";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute("style"),"height"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):"link"===t.message&&(r=new URL(s.getAttribute("src")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener("message",d.wp.receiveEmbedMessage,!1),l.addEventListener("DOMContentLoaded",function(){for(var e,t,s=l.querySelectorAll("iframe.wp-embedded-content"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute("data-secret"))||(t=Math.random().toString(36).substring(2,12),e.src+="#?secret="+t,e.setAttribute("data-secret",t)),e.contentWindow.postMessage({message:"ready",secret:t},"*")},!1)))}(window,document); //# sourceURL=https://museu-angra.cultura.azores.gov.pt/wp-includes/js/wp-embed.min.js /* ]]> */ </script> In optical telegraphy, transmission is carried out using signals perceived by the human eye, through the observation of object positions (semaphores, flags, etc.) or natural (heliographs) or artificial light sources (signal lanterns). Although signal lanterns can be used during the day, they prove particularly useful for nighttime transmissions, as is the case with this […]https://museu-angra.cultura.azores.gov.pt/wp-content/uploads/2025/03/banner-25.jpg630400