Nothing is also seen for "Thimble Theatre" when looking it up under "King Features Illustrated Weekly." in the copyright records, so Poopdeck Pappy is in the public domain
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
Uploaded a work by E.C Segar from Same source as the other photo https://news.google.com/newspapers?id=mT5ZAAAAIBAJ&sjid=80cNAAAAIBAJ&pg=2239,2558703&dq=zephyr&hl=en with UploadWizard