I see some sites use a timeline graph using some Google tools. I am not able to get it in WordPress.
How do I get a timeline graph in a WordPress blog ?
If you are familiar with HTML, you’ll notice that codes such as embed, frame, iframe, form, input, object, textarea and others are missing from the above list. Those codes are not allowed on WordPress.com for security reasons.
In other words, you can't use Timeline.js on WordPress.com