genitive (as _lord's_ for _lordes_): by a false theory the ending was
thought to be a contraction of _his_, as schoolboys sometimes write,
"George Jones _his_ book."

[Sidenote: _Use of the apostrophe._]

Though this opinion was untrue, the apostrophe has proved a great
convenience, since otherwise words with a plural in _-s_ would have
three forms alike. To the eye all the forms are now distinct, but to
the ear all may be alike, and the connection must tell us what form is
intended.

The use of the apostrophe in the plural also began in the seventeenth
century, from thinking that _s_ was not a possessive sign, and from a
desire to have distinct forms.


[Sidenote: _Sometimes_ s _is left out in the possessive singular._]

65. Occasionally the _s_ is dropped in the possessive singular if
the word ends in a hissing sound and another hissing sound follows,
but the apostrophe remains to mark the possessive; as, _for goodness'
sake, Cervantes' satirical work_.

In other cases the _s_ is seldom omitted. Notice these three examples
from Thackeray's writings: "Harry ran upstairs to his _mistress's_
apartment;" "A postscript is added, as by the _countess's_ command;"
"I saw what the _governess's_ views were of the matter."