&gt; I think they also allow for cloudy weather preventing any sights from being taken<p>Is there not a modern equivalent of the medieval &#x27;sun stone&#x27;?<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Sunstone_(medieval)" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Sunstone_(medieval)</a>