The law on the subject is laid down in the well-known case of
Indermaur v. Dames (1) by Willes J., who said, after pointing
out the difference between voluntary visitors to a place, who may
be expected to take care of themselves, and customers invited to
the premises for the purpose of the business carried on by the
defendants : - * And, with respect to such a visitor at least, we
consider it settled law, that he, using reasonable care on his part
for his own safety, is entitled to expect that the occupier shall on
his part use reasonable care to prevent damage from unusual
danger, which he knows or ought to know; and that, where there
is evidence of neglect, the question whether such reasonable care
has been taken, by notice, lighting, guarding, or otherwise, and
whether there was contributory negligence in the sufferer, must
be determined by a jury as matter of fact." In the Exchequer
Chamber on appeal that passage was quoted by Kelly C.B. in
delivering judgment as stating the law correctly (2). The
duty, therefore, of the person occupying the premises is not to
guarantee the safety of the place, but to use reasonable care to
prevent danger to visitors who may be using the premises in any
way that is reasonably to be expected. And the danger with
respect to which he must take care is that of which he knows
or ought to know the existence. Therefore, the omission to
inform himself of the danger, or actual ignorance of its existence,
is not an excuse. It follows that, if the occupier gives warning
to the customer of the existence of the danger, that is evidence
of the use of reasonable care to prevent danger to persons using
the premises with reasonable care. If the occupier does not give