afford examples. In the former case, it was held that a right by the owners of the dominant tenement to go from time to time upon the servient tenement for the purpose of diverting the water of a natural stream flowing along it, so as to cause it to pass through that tenement by an artificial cut to the dominant tenement for the purpose of supplying cattle with water, might be inferred from a user of forty years, and that for the interruption of such easement an action was maintainable. The Court further held, that the fact that the water was diverted by means of an artificial cut did not destroy the right of action by the owner of the dominant tenement. In Saunders v. Newman,' the plaintiff proved a right to the flow of water to a mill for forty years, which mill was burnt down and another erected in its place, with a wheel of the same dimensions as the former one. Since that time, he had erected a new wheel of different dimensions, and requiring less water. The action was brought for injury to this last wheel by a hatch dam or mill head of defendants being raised to a greater height than it had formerly been, and the Court held that the right of action which the plaintiff had for an interference with a stream which had immemorially flowed to his mill, was not destroyed by the alteration of the wheel. "If," says Bayley, J., "a person stops the current of a stream which "has immemorially flowed in a given direction, and thereby prejudices another, he subjects himself to an "action." obstruction creased. Where, however, an easement has been acquired, the Diversion or diversion or obstruction cannot be materially altered or cannot be increased to the further detriment of the servient owner. materially inThus in the case of Bealey v. Shaw' it was held, that where a mill owner had acquired a right by twenty years' uninterrupted user to divert a part of a stream for the use of his mill, he was liable to an action at the suit of a lower 1 1 B. & A. 258. 2 6 East, 208; see also Mason v. C. Hill, 5 B. & A. 1; Alder v. Savile, R A mere alteration does not destroy the right. Easement of pollution. mill owner for a further subsequent diversion to the lower mill owner's injury. So in Brown v. Best,1 where defendant had enlarged certain ancient pits by which he had a right to divert water, and thereby damaged the plaintiff,-it was held that he might have cleaned the pits, but could not enlarge them. A mere alteration in the mode of enjoyment, as the change of a mill from a fulling to a grist mill or the like, whereby no injury is caused to the servient heritage,2 or a trifling alteration in the course of a watercourse, does not destroy the right. Thus in Hall v. Swift3 it appeared that plaintiff had, three years ago, slightly altered the course of a stream, which flowed from lands of defendant through a spout and across a lane to plaintiff's land. The stream had formerly run a few yards down the road before it crossed to plaintiff's land, but the plaintiff altered it so as to make it run straight from the spout to his premises. The Court held this alteration did not destroy the plaintiff's right of action for obstruction of the stream by defendant. A right to pollute the waters of a natural stream is an easement within the Prescription Act, and may be acquired, like any other easement, by user.1 Thus a claim to let off upon neighbouring land water from pits impregnated with metallic substances, and thereby rendered noxious, may be acquired by forty years' user under the Prescription Act. So a right to use a natural stream for the purpose of washing ore and carrying away sand, stones, rubble, and other stuff dislodged and severed from the soil in working a mine, may be claimed by prescription or custom. 1 1 Wils. 174. 2 Luttrel's case, 4 Rep. 86. 3 6 Scott, 167; 4 Bing. N. C. 381. As to effect of alteration on the easement of light, see Barnes v. Loach, 4 Q. B. D. 494; Tapling v. Jones, 11 H. L. 290; National Plate Glass Co. v. Prudential As 6 surance Co., 6 Ch. D. 757; Blan- 6 Carlyon v. Lovering, 1 H. & N. 797; see also Crossley v. Light continuous tible amount Such a right to pollute a stream can only be gained by Can only be a continuance of a perceptible amount of injury to the gained by a servient tenement for twenty years. Thus in Murgatroyd and percepv. Robinson, where an action was brought by the owner of injury for of a mill, which of right ought to be supplied with a flow twenty years. of water from a pool on the river Calder, against the owner of works higher up the stream, for placing cinders, &c. at his works so as to fall into the Calder, whence they were carried down to plaintiff's mill pool and filled it up, and the defendant pleaded that the occupiers of his works had for more than twenty years placed cinders, &c. on the banks of the stream and its channel, the Court held the plea bad, as not showing that the defendant had, during twenty years, of right caused the refuse to go into plaintiff's pool; as till the occupiers of the mill sustained some damage from defendant's user, no right as against them began to be acquired.2 In Goldsmid v. Tunbridge Wells, where an injunction was granted to restrain the draining of a town into a stream passing through the plaintiff's lands, the defendants proved that the sewage of the town had always flowed into the stream, and, on that ground, set up a prescriptive right to continue the discharge. It was, however, proved that though some sewage did formerly flow, and for fifty years had flowed into the brook, that, nevertheless, about ten years ago the water was pure and fit for domestic use, and that the pollution had since then gradually increased. Under these circumstances Sir J. Romilly, M. R., held, the prescriptive right was not proved, and granted the relief prayed. "My opinion is," says the learned judge, "that any person who has a watercourse flowing through "his land, and sewage which is perceptible is brought into owler, L. R., 3 Eq. 279; 2 Ch. 478 Baxendale v. McMurray, L. R., 2 Ch. 790; Wood v. Sutcliffe, 2 Sim., N. S. 163; Murgatroyd v. Robinson, 7 E. & B. 391; Moore v. Webb, 1 C. B., N. S. 673. 17 Ell. & Bl. 391. 2 See Flight v. Thomas, 10 A. & E. 590. 3 L. R., 1 Ch. 352; L. R., 1 Eq. 161; see also Sampson v. Hoddinot, ante, p. 237. Fouling must not be considerably increased. "that watercourse, has a right to come to the Court "of Chancery to stop it; and that when the pollution "is increasing, and gradually increasing from time to time, "by the additional quantity of sewage poured into it, "the persons who allow the polluted matter to flow into "the stream are not at liberty to claim any right or "prescription against him." The case was affirmed on appeal,' Turner, L. J., remarking with regard to the claim of prescriptive right, "I assume, but without meaning to give any opinion on the point, that such a right might well be acquired, but then I think it could be acquired only by a continuance of discharge of the sewage prejudicially affecting the estate, at least, to "some extent, for the period of twenty years; and I "think the evidence sufficiently shows that the discharge "has not prejudicially affected the estate for so long a "period." 66 66 Where a right to pollute a stream has been acquired, the fouling must not be considerably enlarged to the prejudice of the servient tenement, but the user which originated the right must also be its measure.2 In an action for polluting a stream, where a prescriptive right to do so is claimed, it is for the jury to say whether the right claimed is an immemorial and unlimited right of polluting the stream, or the more limited right of doing so for the purposes of a business as carried on for more than twenty years.3 Thus, in the case of A.-G. v. Borough of Birmingham,1 it was proved that, before the passing of the Birmingham Improvement Act, the drainage of the town and neighbourhood was chiefly effected by various small sewers, which flowed into the Rea, a tributory of the Tame; and that the sewage, owing to the distance it had to travel, and to its flowing through a variety of small outlets, became 1 L. R., 1 Ch. 349. 2 Crossley v. Lightowler, L. R., 2 Ch. 478. 3 Moore v. Webb, 1 C. B., N. S. 673; see Rochdale Canal v. Radcliffe, 18 Q. B. 287. 44 Kay & J. 528; see ante, p. 162. gradually purified by filtration, before it reached the estates of the plaintiff, a riparian owner, about seven miles off, so that the waters were well filled with fish, and could be used for brewing and domestic purposes. After the passing of the Act before mentioned, which incorporated the Towns Improvement Act, the 107th sect. of which Act provides, that nothing therein shall render lawful any act, which, but for the Act, would be a nuisance; the whole of the sewage was discharged by a main sewer into the Tame at the point where it was joined by the Rea, and the effect of this was to pollute the river Tame downwards to and beyond the plaintiff's estate, to such an extent that the fish died, and cattle could no longer drink of the water. On an information at the relation of the plaintiff, Wood, V.-C., held, that though the council of the borough were bound by their local act to drain the town, they were not justified in so doing in increasing the nuisance to the extent proved. With regard to the prescriptive right claimed, the learned Vice-Chancellor says, "It was argued that the inhabitants of Birmingham "had a right to drain their houses into the Rea, and "thence into the Tame; but this, at least, is in evidence, "that the alleged right, as exercised (assuming it to be "a right), did not pollute the water of the Tame as it "does now; did not kill the fish, or prevent the cattle "from drinking of the river; but immediately the defen"dants' sewers were opened, the fish were killed in the "river, and the cattle would no longer drink of it; and "their cause and effect are clearly pointed out. The same sort of argument was addressed to me in the Luton "case. There it was contended, and in fact the plaintiff "admitted, that the inhabitants had a right to open their 66 66 sewers into the river; and the defendants, acting on "behalf of the community, claimed to exercise all the "rights which its several members possessed. But the 1A.-G. v. Luton, 2 Jur., N. S. 180; see A.-G. v. Kingston, 13 W. R. |