Radio transmitter/receiver to obtain advice from a mechanic in case of failure.
<bdi><a href="https://en.wikipedia.org/wiki/en:Louis_R%C3%A9my_Sabattier" class="extiw" title="w:en:Louis Rémy Sabattier"><span title="French artist">Louis Rémy Sabattier</span></a>
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Louis Sabattier (1863-1935) (image scannée par <a href="//commons.wikimedia.org/wiki/User:F1jmm" title="User:F1jmm">F1jmm</a>)