Complex sentence: He published an article on "Motion Pictures by Wireless" in 1913, but it was not until December 1923 that he transmitted moving silhouette images for witnesses, and it was on June 13,1925 that he publicly demonstrated the synchronized transmission of silhouette pictures.
Split into simpler sentences: He published an article on "Motion Pictures by Wireless" in 1913, but it was not until December 1923 that he transmitted moving silhouette images for witnesses. On June 13,1925, Jenkins publicly demonstrated the synchronized transmission of silhouette pictures.