Practical Observations concluding John Davies's Patent Cases (1816)
Installment 6 of 6: Miscellaneous Matters, Secrecy and Caveats

Reproduced below is material from Practical Observations concluding John Davies, A Collection of the most Important Cases relating to Patents of Invention (1816). In view of its length and detail, this concluding section of the book is being posted on the blog in six installments.
This sixth installment concerns miscellaneous matters not previously discussed in the Practical Observations. John Davies emphasizes in particular the importance of keeping the invention secret until the patent has “passed the Great Seal”. After the passing of the seal, the patentee was advised to consult others with relevant knowledge and experience who could advise and assist in drawing up the specification. John Davies concludes by discussing caveats and the procedures adopted prior to grant when patent applications interfere with one another.

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It now becomes necessary to state some other matters connected with patents and the rights of patentees, which could not properly be introduced under either of the foregoing heads.
Whenever the patentee brings an action on his patent, if the novelty or effect of the invention be disputed, he must shew in what his invention consists, and that he produced the effect proposed in the manner specified: slight evidence on his part is sufficient, and it is then incumbent on the defendant to falsify the specification. [NOTE: Mr. Justice Buller, in Turner v. Winter, p. 153.]
A patentee, in an action brought by him for infringing his patent, must prove the novelty of every part of that to which his patent applies. [NOTE: Sir Vicary Gibbs, in Manton v. Manton, p. 340, 341.]
In the case Hayne v. Maltby, p. 156, the plaintiffs having a patent machine, covenanted with the defendant that he should use one in the manner described in the specification; in consideration of which he covenanted that he would not use any other. In an action upon the covenant, it was held that the defendant was not estopped by his covenant from pleading in bar to the action, that the invention was not new, or that the patentee was not the inventor, but that he might thus shew that the patent was void, and consequently that he had received no consideration.
But in the case Oldham v. Langmead [NOTE: Cited by Mr. Wigley, in Hayne v. Maltby, p. 157.], where the patentee had conveyed his interest in a patent to the plaintiff, and yet in violation of his contract had afterwards infringed the plaintiff's right; and in his defence attempted to deny his having had any title to convey, stating it not to be a new invention, Lord Kenyon was of opinion that he was by his own oath and deed estopped from making that defence.
An act of parliament having passed for extending the term of a patent for a machine, when in fact the patent was for a process, it was held by Sir James Eyre [NOTE: Boulton v. Bull, p. 218.] that there was nothing technical in the composition or language of an act of parliament, and that it must be expounded not according to the letter but the intent.
An act of parliament enabling a patentee to assign his patent to a greater number of persons than five (to which number it is expressly limited by the patent), and declared to be a public act, does not enable the patentee to make a better title than he could before the act. [NOTE: Hesse v. Stevenson.]
Upon a motion to change the venue in an action for infringement of a patent from Middlesex to Northumberland, it was refused, because the patent, which is the substratum of the action, is tested at Westminster. [NOTE: Cameron v. Gray.]
A patentee having assigned his patent while a suit was depending, reserving the legal estate in the same until the suit should be determined, and covenanting upon the determination of the suit to execute a further assignment, and that until such assignment, the assignee should stand legally possessed of the same; the assignee upon an action brought against him, was nonsuited, upon the ground that no such further assignment had been made; but upon moving for a new trial, it was held by the court that hte legal estate vested without further assignment. [NOTE: Cartwright v. Amatt.]
If the assignees of an uncertified bankrupt, in their own name, executed a deed with other creditors, whereby they release him from all actions, claims, &c. and such deed be not signed by all the creditors, the assignees are not barred from claiming as assignees, the benefit of a patent afterwards obtained. A patent obtained by an uncertified bankrupt is affected by the previous assignment of the commissioners, and vests in the assignees. [NOTE: Hesse v. Stevenson.]
If the assignor of shares in a patent covenants that he has good right to convey, and that he has not, by any means, forfeited any right he ever had over the same; the generality of the former words are not constrained by the latter. [NOTE: Hesse v. Stevenson.]
A person having discovered an improvement upon saddles, communicated his invention to another, who, previously to the communication, undertook by a written agreement not to take any undue advantage of such communication, under the penalty of £1000. He afterwards obtained a patent for this invention in his own name, which the inventor agreed should remain upon certain terms, but which terms the patentee before the action denied, and claimed the improvement as his own invention. In an action to recover the penalty, it was held, that such some could not be considered in the nature of liquidated damages. [NOTE: Smith v. Dickenson, p. 299.]
This case fully shews the necessity of keeping inventions as secret as possible until the patent has actually passed the great seal; for although the defendant was not able to support the patent taken out by him, but agreed at his own expense to assign it to the plaintiff for the remainder of the term, yet the real inventor would have lost the reward of his ingenuity, and the invention would have been laid open to the public at large, had it not been for an expensive and troublesome lawsuit.
It however frequently happens that useful discoveries are made by persons whose circumstances in life will not allow them to bear the expense of obtaining a patent without the assistance of others, who naturally and reasonably expect to be satisfied of the utility and probably success of the invention before they hazard a large sum of money upon a blind speculation; it therefore appears advisable that any agreement between such parties, previously to the disclosure of the invention, should mention a sum, not as a penalty, but with an express declaration that such sum should be considered as liquidated damages, in case of any improper use being made of the discovery, either by bringing it into use before the passing of the patent, or otherwise.
Another instance of the danger an inventor is under of losing the benefit of his invention, by letting it in any way transpire before he has the great seal, may be mentioned, although in this instance it did not succeed. A person had invented an improvement upon spectacles, and as his patent was in a state of forwardness, he had not been sufficiently cautious in keeping the invention to himself, so that another person in the same trade had acquired a knowledge of it, and hastily got a pair made upon the same construction, and exposed them in his window; fortunately, however, the inventor happened to pass the shop, and perceiving them, employed a friend to go an purchase them, in which he succeeded, and his patent passed the great seal the next day, before there was time to get any more made, by which his patent was rendered secure, and most probably a tedious and harassing lawsuit avoided.
As a further confirmation of the necessity of secrecy, we shall only add, that we recollect having heard Lord Eldon, when Chief Justice of the Court of Common Pleas, upon a trial for infringing a patent, say, that during the many years he was first Solicitor-General, and afterwards Attorney-General, so many instances of piracy of inventions had come to his knowledge, that if he was an inventor, he would not disclose his invention to his own brother, until his right was secured by the great seal.
It would therefore be prudent in such cases as machinery, which the inventor, not being perhaps a workman, is unable to construct with his own hands, to employ different workmen to construct detached parts, who are not likely to have any communication with each other, and to be careful not to let them know the connexion or application of the several parts, or the use intended to be made of them.
A person having obtained a patent for an invention, of which he supposed himself the inventor, agreed to let another use it upon payment of a certain annual sum, secured by bond, which sum was paid for several years, when the latter discovering that the former was not the inventor, but that it was in public use before the patent was obtained, brought an action to recover back the amount of the annuity paid, but it was held that he could not recover, as both parties had made the contract in ignorance, and without any fraud. [NOTE: Taylor v. Hare.]
An objection was taken that a specification was not enrolled in due time; but it was held by Lord Ellenborough that the day of the date of the patent is excluded, and therefore if a patent is dated 10th May, and requires the specification to be enrolled within one calendar month next and immediately after the date of the patent, and the specification is enrolled on the 10th June, it is enrolled in due time. [NOTE: Watson v. Pears.]
It now only remains that we should say a few words upon the nature and effect of a caveat, which during our practice we have frequently found to be very much misunderstood. It has been thought by many inventors that upon entering a caveat they secured the right to themselves of obtaining a patent, notwithstanding the invention might be brought into use prior to their having done so; in short, that it was a kind of minor patent, giving them every privilege for one year which the patent itself would do for fourteen, or that it would operate as a proof of their being the first and true inventors, and that upon their afterwards obtaining a patent they would be able to maintain it against any person who, in the mean time, might have made use of the invention; in order to obviate such erroneous ideas, it is necessary to explain the nature and effect of a caveat.
A caveat is merely a desire that if any person should apply for a patent for any particular invention, notice of such application should be given to the party. This caveat is usually entered at the offices of the Attorney and Solicitor-General, and upon an application to either of them for his report upon a petition to the king for a patent for any discovery of the same nature as that described in the caveat, notice is given to the person who has taken this precaution, which gives him an opportunity, if he thinks the inventions interfere with each other, of opposing the application. If it is meant to oppose, the Attorney or Solicitor-General before he makes his report will give a separate audience to each party, and examine the nature of the two inventions, and according to his opinion of their similarity will make his report or not: if he is of opinion that there is a material coincidence, he will not report in favour of the application; but if otherwise, he makes his report, and the patent proceeds in its regular course. If however the party entering the caveat is not satisfied with the decision of the Attorney or Solicitor-General, he has another opportunity of opposing by entering a caveat at the great seal, when the Lord Chancellor will himself give a similar audience and examine the pretensions of the parties. This practice is not often recurred to, as it is attended with much expense, and the Chancellor usually orders all costs to be paid by the party opposing if he does not succeed, as he is averse to the caveat in so late a stage of the business after great part of the expense of the patent has been incurred.
The caveat reamins upon the books for one year, and may be renewed from year to year as long as may be considered requisite.
If it is thought necessary to enter a caveat, it is proper to use general expressions rather than to express the precise invention, as by that means the inventor would receive notice of any application for a patent connected with the subject of the invention mentioned in the caveat, which might not be the case if the particular invention or improvement should be exactly identified. Another reason for general expressions is to guard against the opposite party obtaining a knowledge of the invention, as he might be able to affect the validity of the patent by publishing the invention before the patent is sealed, which would have the effect of throwing the invention open to the public. But it will sometimes happen that two ingenious persons may, without any improper communication, make a discovery of a similar invention, in which case upon the similarity of the invention appearing to the Attorney or Solicitor General, it is usually recommended that the parties should unite interests, and take out a patent in their joint names, which seems to be the most prudent plan for both parties, as priority of invention would be of no avail if the other party should be inclined to publish the invention so as to affect the patent. We cannot however too much reprobate a practice which has of late grown into use by some speculative persons of keeping a list of caveats upon general principles entered in the books without any idea of obtaining patents themselves, but with the sole view of being acquainted with every improvement that is going on, whereby they gain an opportunity of coming to a compromise with the real inventors, and sometimes have obtained large sums of money from them to withdraw their opposition.
With respect to the description or title of the invention, we would observe, that the utmost consideration should be given before the inventor swears to the invention, as the title given in the affidavit and petition cannot afterwards be altered, it is therefore necessary that it should be sufficiently clear to identify the invention, and yet so general as to admit of some degree of latitude in the specification; but the greatest care should be taken that it does not comprehend more than is really the invention of the applicant, as it will be seen by some of the cases reported in this work, that patents have been set aside upon the ground of claiming too much.
But the rock upon which most patents have perished when brought into a court of law is a defective specification, and therefore it is adviseable, particularly in cases of complicated and extensive machinery, or any invention founded upon scientific principles, that the patentee should not depend too much upon his own judgment in drawing up that instrument, but that he should consult men of known and acknowledged science and ability in the particular branch to which the invention relates, who will perhaps not only be assistant towards the elucidation and proper description of the particular invention, but from their general knowledge will be able to point out parts of what the patentee thinks himself to be the inventor which have been previously in use, and which if claimed by him might have the effect of vitiating his patent if ever it should have the misfortune to undergo the ordeal of a court. The patentee may do this without hazard of an infringement upon his patent or any improper use being made of the communication, as the grant having passed the great seal has secured the right to him beyond the danger of imitation.
An additional reason why those skilled in such subjects should be consulted appears to be, that advantage is likely to result from taking the opinion of men who had nothing to do with the invention, as they must necessarily be more likely to give a particular and exact description of an invention than the inventor himself, who from having intimately considered and reflected upon all the parts before it could be brought to maturity, has become so familiar with the whole as to imagine that it was equally clear to others, and that a skilful person might be able to carry the invention into effect by means of such a description as would leave much to be supplied by his own ingenuity and contrivance, which should carefully be avoided.
The foregoing cases and the few imperfect observations here offered to the public will, it is hoped, have the effect of drawing the attention of patentees more particularly to the law of the subject, and enabling them, by knowing what defects have heretofore had the effect of rendering patents void, to make their specifications more clear and explicit than in former times, whereby patents may become more certain, and ingenious persons be induced to promote useful improvements in the arts and manufactures of the country by being acquainted with the means of making the tenure of a patent more stable and solid than of late years it has been found to be; an event much to be desired for the sake of those who devote their time and labour, and are very often at great expense in bringing to perfection things important and advantageous to the trade and commerce of the kingdom.

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