Decimal point

In 1617 in his Rabdologia John Napier referred to the period or comma which could be used to separate the whole part from the fractional part, and he used both symbols.
In 1704 the term Separating Point is used in the Lexicon Technicum in the entry "Decimal."
According to Cajori (vol. 1, page 329), "Probably as early as the time of Hutton the expression 'decimal point' had come to be the synonym for 'separatrix' and was used even when the symbol was not a point."
Decimal point appears in the 1771 edition of the Encyclopaedia Britannica in the article "Arithmetick": "The point thus prefixed is called the decimal point" [James A. Landau].
In 1863, The Normal: or, Methods of Teaching the Common Branches, Orthoepy, Orthography, Grammar, Geography, Arithmetic and Elocution by Alfred Holbrook has: "The separatrix is the most important character used in decimals, and no pains should be spared to impress this on the minds of pupils."