How to Do a Read More Post on Tumblr
When you publish a long post on your Tumblr blog, the length might decrease the readability of the blog because Tumblr's layout is optimized for short-form content, such as brief posts, videos, pictures and quotes. For this reason, Tumblr gives you the ability to insert a "Read More" break in a post. Using this feature, you can make the front page of your Tumblr blog display a brief excerpt of your post. Interested readers can click the "Read More" link to view the full content.
Click the "Text" icon at the top of Tumblr's Dashboard to begin creating a new post.
Type the title and content of the post as you normally would, using the "Title" field to add the title and using the text editor to write the content.
Place the cursor at the location in the post where you would like the "Read More" break to appear. Everything before the location of the cursor will appear on the front page of your Tumblr blog. Everything after the cursor will appear in the full version of the post, which readers must click "Read More" to see.
Click the "Insert Read More Break" button at the top of the text editor window. The button looks like two sheets of paper with a dotted line in between. You should now see the words "Read More" in your post.
Click "Create Post" to publish the post.