hobbits measure this with bookfeets

[aamcnamara]

bookfeet (bŏŏk-fēt) pl. n. Unit of measurement in books, in terms of how much shelf-space a given amount of volumes take up; e.g., "How many books are you bringing to college?" "Oh, about five bookfeet."

Comments

[browniecakemix.livejournal.com]

To shelve them horizontally-endwise is also quite useful when running out of room... although it's a shame not to be able to see the spines.