efit of the works which he has so erected, and the patentee has kept his contract with the defendants; he has not interposed and endeavored to deprive them of the benefit of their expenditure. It is the act of the manufacturer which has put an end to this connection; he has therefore exposed himself to any degree of injury that may arise from the expenditure upon these works, and it appears that there is no answer to the claim to this rent from August, 1839, to August, 1840. I shall have to consider, if your client declines to escape from the injunction upon the terms I propose to him, whether the injunction should not go in a case which is deprived of those equitable circumstances which induced me to dissolve it in the others. [Wigram. Your lordship will give me the benefit of the supposition that, at law, I have a defence if the patent is good for nothing.] If you can show me that there is a real question to try, the money must be paid into court instead of being paid to the parties; but at all events, I do not see how for that year, from August, 1839, to August, 1840, when you went on under the contract without giving notice to determine, you can escape paying it, either into court to abide the event of the trial of the question at law, or paying it to the party if there is no question to try.

Wigram. Your lordship said you should consider whether, since August, 1840, we were to be considered as holding adversely, and, therefore, whether liable or not to pay for what was gone by; we were at all events wrongdoers. And then you put me to show whether I could not in law defend myself for what was said to be due in August, 1840. The principle which I have always understood to govern cases of this sort is this, that, excluding the law of estoppel, if you go into a court of law, and can show a total failure of consideration for the contract, there you may always defend yourself; if, on the other hand, you cannot make out a case of total failure of consideration, you are liable upon your contract, and you may or may not have your cross-action. This is the general principle in these cases, subject to the question whether that which has been done may or may not amount to an estoppel. The whole

question in the case of Bowman v. Taylor, relied upon for the plaintiff, was whether or not there could be an estoppel by recital, and it was held that there could. In Hayne v. Maltby (1 ante, p. 53) the question was whether there was any estoppel, there being no recital of the plaintiff's title, but only an agreement and a covenant to pay, and the court held that there was not. In that case Ashurst, J., said the plaintiffs use this patent as a fraud on all mankind, and they state it to be an invention of the patentee, when in truth it was no invention of his. The only right conferred on the defendant by the agreement was that of using this machine, which was no more than that which he in common with every other subject has, without any grant from the plaintiff. That is exactly our case. We say that all mankind have a right to use it, but that some people have taken licenses, supposing it to be the plaintiff's invention. On the money then being paid into court, the injunction should be dissolved.

Lord COTTENHAM, L. C. The case of Hayne v. Maltby appears to me to come to this that, although a party has dealt with the patentee and has carried on business, yet that he may stop, and then the party who claims to be patentee cannot recover without giving the other party the opportunity of disputing his right, and that if the defendant successfully dispute his right, notwithstanding he has been dealing under a contract, it is competent to the defendant so to do. That is exactly coming to the point which I put, whether, at law, the party was estopped from disputing the patentee's right, after having once dealt with him as the proprietor of that right; and it appears, from the authority of that case and from the other cases, that from the time of the last payment, if the manufacturer can successfully resist the patent right of the party claiming the rent, he may do so in answer to an action for the rent for the use of the patent during that year. That being so, I think, upon the money being paid into court-that is to say, upon the amount of the rent for that year being paid into court (if required), and the same undertaking being

given to account for the subsequent period, the same order ought to be made in this case as in the others. There must be an undertaking to deal with the amount of that in the same way as before. The great difficulty in this case, which, however, is surmounted in the undertaking, is that the said suit does not go to that year's rent.

Order accordingly.

The same order was made in Neilson v. Harford and Neilson v. Homfray, the circumstances being substantially the

same.

NEILSON v. THOMPSON.

Chancery, Jan. 21, 1841.

(1 Web. P. C. 278.)

Effect of Delay in Applying for Injunction. Account.

An injunction should not be granted where it would cause irreparable injury to defendant.

The public are entitled to know for what it is that the patentee claims the invention, that they may be saved inconvenience upon the subject; therefore, the specification must tell the public for what it is that he claims protection.

Where plaintiff applied for an injunction against infringement, only after several years' knowledge of the facts, and irreparable damage to defendants would ensue if it were granted, held, that an account merely should be ordered to be kept.

Appeal to discharge injunction.

The proceedings below are reported at p. 136, where the patents in question appear. Several additional affidavits were filed on both sides. On the part of the defendants, it was stated that the apparatus made according to Neilson's directions did not succeed; that various experiments were made, and all the attempts before the syphon or arch pipes were not only unsuccessful, but injurious; that a person named Condie was the inventor of the present apparatus now used so successfully; that the invention of Neilson is

substantially the same as the prior one of Botfield, both in principle and apparatus, and both totally useless; that the apparatus of pipes in use is altogether different from anything described by Neilson, both in principle and construction; that many parts of Neilson's specification are false, and calculated to mislead; that defendants applied the hot air to one furnace in November, 1838, and to another in November, 1839, and that the cost for each furnace of the requisite apparatus is £750.

On the part of the plaintiffs were affidavits by Neilson stating his belief that he was the true and first inventor of that for which the letters patent were granted, and which was described and claimed in the specification, and that air artificially heated while in current or blast had not been openly or publicly used prior to the date of the patent; that the invention was highly beneficial, and used by many iron-masters under licenses; that no compromise ever took place on his part with any party except on the terms of paying one shilling per ton.

It was stated in other affidavits that thirteen parties in Scotland and fifty-eight in England had taken licenses; that the inventions of Botfield and Neilson were totally and essentially distinct; the former being mechanical, or a method of creating a blast, by which the air was necessarily rendered unfit to support combustion-the latter being chemical.

Wigram, Richards and Roupell moved to discharge the order of the Vice-Chancellor.

The utmost that the plaintiffs can ask under the circumstances of this case, on the ground of the length of time which the patent has been in existence, is for an account, and this the defendants have always been ready to keep. The patentee does not in this case make his profit by selling the article, but by granting licenses to iron-masters to use his patent on paying one shilling per ton on all the iron made. The defendants, until the validity of the patent was tried, ought not to be compelled either to pay the one shilling per ton or to take a license, experience having shown that those persons who were so incautious as to pay the one

shilling per ton or to take a license were very much hampered in case of the patent being disputed. The action at law will be tried as soon as possible, but the defendants ought not in the mean time to have any other terms imposed than keeping the account and undertaking to pay one shilling per ton in the event of the title to the patent being established, because the apparatus described by the specification did not come into use at all, but an apparatus essentially different came into use some years afterward. If an injunction be granted in the mean time, and the patentee fail in establishing his title, the defendants will lose all the expense which they have been at in preparing the furnaces, whereas, if he succeed, the plaintiffs will be paid eventually.

It appears from the bill and the affidavits that there was acquiescence for more than a year before the bill was filed; no agreement is stated, but simply acquiescence, in expectation that the defendants would pay on finding it answer. Supposing the patent good, there was no ground for a court of equity granting an injunction as the case stood upon the bill-namely, upon the expectation that a license would be taken. The case of a person making a patent article and selling that article is totally different from the present case, in which the profits arise entirely from the granting of licenses. In the former case irreparable mischief may be done, the party losing the benefit of the sale, and being liable to be prejudiced in his credit from the articles being of an inferior quality, so that the court may not be in a position to do complete justice to the patentee; but in the present case no injury can be done by requiring the patentee to establish his patent, an account being kept in the mean time, there being no doubt as to the abilities of the parties to pay. An expense of more than £5,000 has been incurred by the plaintiffs' acquiescence in the erection of the works, and in cases of acquiescence the court will say keep an account, and the parties will be interested in trying the question at law with dispatch.

The extraordinary relief of an injunction will not be granted to a patentee unless he states distinctly what he