Ong Hock Thye FJ:

This is an appeal against the judgment of Gill J holding the appellants liable for damages under the rule in Rylands v. Fletcher [1865-6], LR 1 Ex 265; 19 LT 221.

It has fallen on me to lead off with this judgment, although I should have preferred to inform myself first of the judgments of my abler, learned colleagues I shall, therefore, concentrate mainly on the questions of fact which in my opinion are sufficient for the determination of this appeal and leave it to them to dilate on the questions of law.

There is practically no controversy as to the primary facts. The appellants, for the purposes of their dredge-mining operations, maintained on their lands large ponds or reservoirs of water which were separated from each other by intermediate bunds, with one perimeter bund enclosing all these bodies of water. By means of spillways, the flow of water from one pond to another, as well as its ultimate discharge into a river, was regulated and the water-level of each pond maintained as desired. We are here concerned only with two ponds, designated as P1 and P2, and with the bund separating them, referred to as bund A.

The topography of the appellants' lands was described by a mining engineer Mr. Waugh. They are situate in an inclined valley, approximately 2'bd miles in length, the drop in ground level being 60 feet over this stretch. Another feature is that this mining area is within a catchment basin of some ten square miles, with two rivers of large and variable run-off flowing through it. As the mining and slimes retention areas were all in the slope of the valley, the appellants met the problem by constructing a series of step ponds to control the slimes and provide water-cushions for preventing erosion. Because of the 60-foot drop it was necessary to carry the water above ground and the ponds, used also for slimes retention, had to be above the level of the surrounding lands for the same reason.

It was not in dispute that a large breach in bund A caused such a violent outflow from P1 into P2 that the combined volume of water from both ponds broke through the perimeter bund and caused all the damage for which the present respondent has sought compensation. His claim, for present purpose, rested on two grounds, namely, negligence and the rule in Rylands v. Fletcher. The appellants had repudiated all liability.

The fundamental question for determination was: What caused the breach in the bund? It was the appellants' case that the breach was due entirely to the irruption of a subterranean spring, which, if true, was clearly unforeseeable and an Act of God. This would have afforded a complete defence to the action.

The trial Judge, having decided against the respondent on the issue of negligence and against the appellants on the applicability of the rule in Rylands v. Fletcher, both parties now appeal to this Court.

I shall deal first with the case for the appellants, but, before I proceed to do so, I feel I ought to express my indebtedness to the learned trial Judge for a careful, lucid and comprehensive summing up of the relevant evidence in his judgment. The exercise he faced was a difficult one, having been set the task of exploring the arcanum of recondite subjects on which expert witnesses gave such voluminous evidence that it became hardly possible to see the wood from the trees.

According to the pleadings, however, it lay on the appellants to prove affirmatively that it was a spring from an artesian source which caused the collapse of the bund. Their evidence on the one hand, was that the collapse was due to piping caused by a spring which manifested itself in the manner described by experts. On the other hand, they claimed that, but for the spring, the collapse could not have occurred because the bund was so soundly constructed that all other possible causes could be eliminated.

The appellants' case thus presented two aspects, positive as well as negative. For the former they relied o