Arrange 3 Knives to Rest on Tips of Handles/Variant/Mistake

Source Work

 * The Puzzles:
 * Henry van Etten
 * $112$
 * $112$

Mistake

 * Variants in Victorian puzzle books demanded how three knives might be used to support a drinking glass, in the ample space between three other drinking glasses placed on the table with more than enough space for a fourth glass to be placed on the table between them.

Correction
If you count carefully:
 * one glass to be balanced
 * three glasses forming the ample space

you notice that the glass to be placed on the table between them is actually the fifth glass.