Lectern

A lectern is a librarian's job site block found in villages. It is used to hold books for multiple players to read in multiplayer.

Natural generation
Lecterns can generate in village libraries.

Breaking
Lecterns can be broken with any tool, but an axe mines it the fastest. Lecterns drop themselves and the book they are holding.

Usage
Lecterns hold a single book and quill or written book that other players can read at the same time. Right-clicking an empty one with a book and quill or written book places it. Right-clicking a lectern with a book already occupied opens an interface to read the book. Books occupying a lectern can be retrieved through the interface, punching the lectern or by destroying the lectern, even when /gamerule doTileDrops is false.

Redstone signal
Lecterns holding a book emit a redstone pulse that is one game tick long (0.5 redstone ticks) when a page is turned. A redstone comparator also records book reading and sends a signal, depending on what page the player is currently on. Because displays two pages of the book at once, the same signal strength increments require double the number of pages.

For Java Edition a book with only 1 page gives maximum signal strength, however page 1 always gives 1 signal strength no matter what if a book contains at least 2 pages.

Due to this, to calculate the signal strength $$S$$ of books with more than 1 page, use the following formula:

$$S = \left\lfloor 1 + \frac{14(P-1)}{M-1} \right\rfloor$$

Where $$\lfloor \, \rfloor$$ is the "floor" operation (round down), $$M$$ is the maximum number of pages the book on the lectern has, and $$P$$ is the current page number the lectern is turned to.

This is most noticable when a book has 2 pages where the signal strength is either 1 on page 1 or 15 on page 2.

A book that would step up or down in increments of 1 per page would be 15 pages long.

For the formula is slightly different. Due to Bedrock showing 2 pages at once and counting a change to the book's output only if the highest even numbered page contains information, a redstone comparator treats books with 3 pages the same as those with 1 or 2 pages of information, the same as how Java would treat a book with just 1 page.

For 4 or more pages of information use the following formula to calculate signal strength.

$$S = \left\lfloor 1 + \frac{14(P'-1)}{M'-1} \right\rfloor$$

In this case $$M'$$ is half of the maximum page number rounded down, and $$P'$$ is half of the current highest page number containing data displayed on the book interface, rounded down.

Rounding down is required to eliminate the discrepancy caused by books containing an odd number of pages. For example, a book with 8 pages gives a signal strength of 15 when looking at pages 7-8. A book with 9 pages has a signal strength of 15 when looking at either pages 7-8 and 9-10.

In, a book that steps up or down in increments of 1 per page turned must be exactly 30 pages long, with information left on page 30.

Changing profession
If a village has a lectern that has not been claimed by a villager, any villager has a chance to change their profession into librarian if those villagers have not already chosen a job site block.

Fuel
Lecterns can be used as fuel in furnaces to smelt 1.5 items.

ID




Block data
A lectern has a block entity associated with it that holds additional data about the block.