What rule has been laid down in the case of Rylands v. Fletcher in regard to liability?

–   Strict liability has its origin in the Rylands v. Fletcher, where the facts were that the defendants who had a mill near Ainsworth in Lancashire wanted t improve its water-supply. They constructed a reservoir by employing reputed engineers to do it. When the reservoir was filled, water flowed down the plaintiff’s neighbouring coal mine causing damage.  The engineers were independent contractors. There was some negligence on their part in not properly sealing disused mine shafts and it was through those shaft that the water flooded the plaintiff’s mine. The Court of Exchequer dismissed the claim as showing no cause of action. But the Court of Exchequer Chamber allowed the appeal. The judgment of that Court laid down a new basis of liability which was subsequently approved by the House of Lords. The Court laid down the basis of liability in these words: “the rule of law is that the person who, for his own purpose, brings on his land and collects and keeps there anything likely to do mischief if it escapes, must keep it in at his peril’ and if does not do so is prima facie answerable for all the damage which is natural consequence of its escape.”