it distinguish clearly the later improvements from the earlier invention; for notwithstanding the case of Harmer v. Playne (11 East. 101), there is reason to suppose that unless it can be seen on reading the second instrument, after the expiration of the earlier patent, of what the later invention consists, as something distinguishable from an old part, the second patent would be pronounced invalid.

The fatal effect of ambiguous language in a specification is illustrated by the case of Hastings v. Brown (17 Jur. 648; S. C., 1 E. & B. 454). Charles Johnstone obtained the grant of a patent on the 21st December, 1844, for an invention of "certain improved arrangements for raising ships' anchors, and other purposes." The specification claimed as the invention "a cable holder to hold without slipping a chain cable of any size," but it could not be gathered from it whether the inventor claimed a cable holder to hold a chain cable of any one size, or to hold chain cables of different sizes. Now, a cable holder to hold a chain cable of any one size was already known at the date of the patent. "The patentee," said Lord Campbell, when the case was argued before the Court of Q. B., on a motion to enter a nonsuit, "ought to state distinctly in his specification what is his invention, and to describe the limits within which he is to enjoy a monopoly. That is not done in this case with respect to the nature of the cable holder. What is claimed [in the pleadings] is a right to construct a capstan which will raise chain cables of different dimensions. Does the plaintiff disclose in his specification that he claims that invention ? If it is only claimed with regard to one cable, then there is no infringement of the patent. The vice of the specification is, that it is quite equivocal what the claim is. There is nothing in the title which at all assists us;

and when we look to the description in the specification, which speaks of a chain cable of any size,' I think that the proper construction to be put upon the words is that they mean one chain cable.' At all events, they are capable of that meaning; and if the specification is equivocal, it is bad." And Mr. Justice Coleridge added, "If the specification on a fair interpretation be equivocal, it is insufficient." The rule for a nonsuit was accordingly made absolute.

The specification under a patent for certain methods of making cements, described a method of making cement from gypsum, in the course of which an alkali, neutralized by an acid, was directed to be used; sulphuric acid and potash being stated to be the best acid and alkali for the purpose. Another method for making cement from limestone and chalk was then described, and consisted also in the use of alkali, neutralized by an acid. An action was brought for an infringement of this patent. The infringement complained of was the use of borax in making cement, borax being composed of an acid (boracic acid) and an alkali (soda). The patentee, however, failed, on account of his defective specification. If he confined himself to sulphuric acid and potash, then the defendant was not liable, seeing that he had used neither; if he claimed the use of all acids and alkalies, his claim was bad, because it was proved that there are some acids and alkalies which would not answer the purpose; and if he claimed only those acids and alkalies which were proper and suitable, he was bound to state what they were, otherwise experiments would have been necessary to discover what were suitable and what were not. (Stevens v. Keating, 2 W. P. C. 194.) See also Muntz v. Foster (2 W. P. C. 109).

Hills, in the specification under his patent for the purification of gas, claimed the use of "hydrated or

precipitated oxides of iron." Now, if this meant all hydrated oxides of iron, the claim would have been too large, inasmuch as some of them would not effect the purpose, and the defendant, in an action for an infringement of the patent, argued that this was the meaning. The Court of Exchequer, however, although admitting that the language was not accurate, held, in their desire to uphold the specification, that the patentee meant to refer to such hydrated oxides as were precipitated. (Hills v. London Gas Light Co., 5 H. & N. 312.)

If the specification contains language calculated to mislead as to an important part of the patented process, as where it contains positive misdirections as to the mode of operating, the patent will likewise be void. "You must not mislead people" (said Jessel, M. R., in Plimpton v. Malcolmson, 3 L. R. Ch. D. 531, 576)" by telling them to do something wrong, and leaving them to find out the mistake. . . . You must not give people mechanical problems and call them specifications."

On the trial of Palmer v. Wagstaff (Newton's Lond. Jour. vol. 43, p. 131), an action brought by a candle manufacturer for an infringement of a patent for improvements in the manufacture of candles, it was alleged that the specification contained a positive misdirection as to the position in which the wicks were to be placed in the process of manufacture. The object proposed was the production of a candle requiring no snuffing, by using two or more plaited wicks, arranged in such a manner that they would separate and bend outwards as the candle was burned. Now, it was shown that if the directions of the specification were followed, the candle would require lighting at the bottom, instead of the top. If lighted at the top, the wicks converged, instead of diverging, and pro

duced a long snuff. The judge (Pollock, C. B.) told the jury that this was a serious mistake, and though the verdict was given against the plaintiff upon other points than those connected with the validity of the specification, there is reason to suppose that this instrument could not have been supported. See also Savory v. Price (1 Ry. and Moo. 1; 1 W. P. C. 83); Bickford v. Skewes (1 W. P. C. 218).

It has also been decided, that if two methods of doing a thing are described in the specification, and by one of these it cannot be done, the specification is bad. (The Queen v. Cutler, Macr. P. C. 137; Beard v. Egerton, 8 C. B. 165.)

Medlock's specification of his invention for making red and purple dyes from aniline commenced the description of the process thus: "I mix aniline with dry arsenic acid and allow the mixture to stand for some time, or I accelerate the operation by heating it to or near its boiling-point until it assumes a rich purple colour, and then I mix it with boiling water and allow it to cool: when cold it is filtered and decanted." When the case went before the House of Lords, it was held, in affirmation of the view taken by the Lord Chancellor, that on the construction of the whole specification two processes, a hot and a cold process, were described, and as it was proved that only the hot process was effective, the specification was declared to be bad and the patent consequently invalid. It was urged that every person well informed on the subject could see that the cold process was ineffective, but "this," it was said, "would be to correct the specification by the superior intelligence of the reader." (Simpson v. Holliday, 13 W. R. 577, affirmed L. R. 1 H. L. 315.)

In Booth v. Kennard (2 H. & N. 84), an action brought for the infringement of a patent for improve

ments in the manufacture of gas, the specification was held bad, because it claimed generally the exclusive privilege of making oil directly from oleaginous seeds; and, instead of describing particularly how this was to be done, only stated that the mode of using the materials might be "the same as in the apparatus used in the ordinary mode of making gas from coal." The Court deemed such a description too vague and general, when coupled with a sweeping claim like that above mentioned. And the Court came the more readily to this conclusion, when it appeared that the principle or leading idea of the alleged invention was not new.

Then as to the general tenor of the specification, the language must be clear and precise; the explanation must be intelligible to a person of ordinary skill and ability, acquainted with the particular subject; and the directions such that, by pursuing them, he would produce without difficulty the result which the patentee describes. (Tindal, C. J., in Gibson v. Brand, 1 W. P. C. 631; Beard v. Egerton, 8 C. B. 165.) Lyndhurst, L. C., said, in Sturtz v. De La Rue (1 W.P.C. 83 n.), that the specification must describe the invention in such a way, that a person of ordinary skill in the trade should be able to carry on the process. And Lord Denman, in Bickford v. Skewes (1 W. P. C. 218), said that the specification is addressed, not to persons entirely ignorant of the subject-matter, but to artists of competent skill in the branch of manufactures to which it relates. The persons whom the specification ought to be designed for are persons of ordinary skill and ability; not those of special and unusual practice, knowledge, and capacity; not persons at the head of their profession. (Morgan v. Seaward, 1 W. P. C. 178; Neilson v. Harford, 1 W. P. C. 371; Househill Co. v. Neilson, 1 W. P. C. 692; Plimpton v. Malcolmson, L. R. 3 Ch. D. 531.)