One of the three small <i>Alfa</i> class launches, built by Thornycroft for the Brazilian Navy in 1883. They were intended for river service and armed with a single spar torpedo. The photo appears to be taken near Chiswick prior to shipment to Brazil.
Unknown photographer of the time
<a rel="nofollow" class="external text" href="https://www.history.navy.mil/our-collections/photography/numerical-list-of-images/nhhc-series/nh-series/NH-59000/NH-59871.html">history.navy.mil</a> Cropped and saved to png format by uploader.