<p><i>Longitude and Latitude of St Petersburgh</i>, a caricature of Countess Lieven waltzing at Almack's by <a href="//commons.wikimedia.org/wiki/George_Cruikshank" title="George Cruikshank">George Cruikshank</a>, May 13th 1813.  Countess Lieven was the one of the lady patronesses of Almack's, and was the wife of the Russian Ambassador. (St Petersburg was then the capital of the Russian Empire.)
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Two of the men in the background have collapsible <a href="https://en.wikipedia.org/wiki/Bicorne" class="extiw" title="en:Bicorne">bicornes</a> tucked under their arms.  Some of the musicians making the dance music are visible in a gallery at upper left.
<bdi><a href="https://en.wikipedia.org/wiki/en:George_Cruikshank" class="extiw" title="w:en:George Cruikshank"><span title="British caricaturist and book illustrator; (1792-1878)">George Cruikshank</span></a>
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1813-05-13
Scanned by H. Churchyard