Charles Greeley Abbot's signature (with an alpha channel) from a 1916 memorandum.
<bdi><a href="https://en.wikipedia.org/wiki/en:Charles_Greeley_Abbot" class="extiw" title="w:en:Charles Greeley Abbot"><span title="American astrophysicist and the 5th Secretary of the Smithsonian">Charles Greeley Abbot</span></a>
</bdi>
1916-10-02
<a rel="nofollow" class="external free" href="http://siarchives.si.edu/history/exhibits/stories/october-2-1916-assistant-secretary-abbot-secretary-walcott-goddards-proposa">http://siarchives.si.edu/history/exhibits/stories/october-2-1916-assistant-secretary-abbot-secretary-walcott-goddards-proposa</a>