A bone crusher was a device for crushing animal bones. Bones obtained during slaughter were cleaned, boiled in water and dried for several months. After that, they were suitable for crushing with the special machine into a relatively dry gritty powder which was used as fertilizer.

The machine, shown in the picture, is water wheel

Water wheel

A water wheel is a machine for converting the energy of free-flowing or falling water into useful forms of power. A water wheel consists of a large wooden or metal wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface...

 powered. It contains eight S-shaped pairs of cams that raise the crushers alternately and let them fall into material to be crushed. The simple transmission increases the rotation speed of the crusher wheel to 21 rpm from the water wheel speed of about 7 rpm.

Bone meal

Bone meal

Bone meal is a mixture of crushed and coarsely ground bones that is used as an organic fertilizer for plants and formerly in animal feed. As a slow-release fertilizer, bone meal is primarily used as a source of phosphorus....

 was used since about 1790 as a welcome supplement to the ordinary farmyard manure. From about 1880 it was supplanted by chemical fertilizers.

Similar machines

A similar machine (the Stamp mill

Stamp mill

A stamp mill is a type of mill machine that crushes material by pounding rather than grinding, either for further processing or for extraction of metallic ores. Breaking material down is a type of unit operation....

) is used to crush ore in mining situations.