The spyglass in the menu reveals a pop-out search tool, enter a word or a user-name and hit return!
Search with filters
Items grouped under topics are nested under WHAT and WHEN headers; e.g. below, I have selected: WHAT > Industry and Commerce > Coal
You can narrow results by selecting to only see Items, Collections, Trails or Stories: click the filters across the top.
Clearing a filter is simple, click the x in the blue tag to clear.