ounded
on his negligence. The same is true of his liability for electricity
escaping from his control. In both cases the care he must exercise in
guarding the dangerous element varies with the hazard to which it
exposes others."

The liability of a person who keeps explosives is not absolute, unless
he is maintaining a nuisance. Otherwise he is liable only when
negligent. If he is ignorant of the character of the explosive, and
without fault in not knowing, his duty of care is fixed by the
apparent character of the article. Suppose a carrier was carrying a
trunk containing an explosive of which he had no knowledge or reason
for supposing was there, surely he would not be held liable if it
exploded and caused injury.

The liability of a manufacturer, seller, lender, or user of things is
not that of an insurer in making, selling, lending or using them. But
he does incur liability whenever he fails to exercise such care as is
fairly needful to protect others against the hazard in buying and
using them. A druggist, therefore, who affixes a wrong label to a
bottle of medicine and thereby injures a person who uses it is
responsible. And the rule would apply whether the taker was the
purchaser or some other person.

When persons are invited on one's premises for mutual advantage, the
inviter owes the duty of ordinary care. He is not an insurer of their
safety, nor need he exercise extraordinary care in guarding them from
harm, unless there was unusual danger. Suppose a man had a way which
persons used in going to and from his business, and he began to dig a
well near the way and left the place unprotected during its
construction, undoubtedly the owner would be liable. Suppose the well
was a considerable distance from the way where persons did not usually
go and had no occasion for going. Then he would not be liable. How far
away from the road could he dig without thought of the public? The
answer would depend on the facts in the case.

A somewhat different rule has been applied to children. Although a
child of tender years who meets with an injury on the premises of a
private owner may be a technical trespasser, yet the owner may be
liable, if the things causing the injury have been left exposed and
unguarded, and are of such a nature as to be attractive to children,
appealing to their childish curiosity and instincts. Unguarded
premises, which are thus supplied with dangerous attractions, are
regarded as holding out imp