current which passes through it will also circulate in the coarse wire, thus increasing the efficiency of the device. This arrangement, illustrating one of the most prominent applications of my invention, is shown in Fig. 1. Fig. 1 represents in plan view a portion of a dynamo-electric machine, showing one of its magnetic helices partially wound and so arranged as to exhibit the 'teaser' (E) and helix F, also to show one form of arranging the currents of the teaser and main wire. Fig. 2 is the same, showing, however, a modified arrangement of the currents of the teaser and main wire. Fig. 3 shows a modified method of applying the teaser by wrapping it upon the outside of the main helix instead of within it, as shown in Fig. 1. Fig. 4 shows another modified form of teaser, where it may he wrapped around the magnet alongside and independent of the main helix. . . . It is not at all essential that the teaser (E) be wrapped around the magnet underneath the wire F. A variety of methods would be equally as operative as the above, the essential object being that the teaser wire shall form a helix around the field magnet; and this may be accomplished in many ways, among which may be mentioned that illustrated in Fig. 3 of the drawings, where the teaser is wrapped outside of the helix F; also that shown in Fig. 4, where the teaser is wrapped alongside the helix F, forming a separate and independent section or helix."

The seventh claim (in the amended specification) was :—

"(7) In a dynamo-electric machine the wire or helix E, having a comparatively high resistance and kept in closed circuit while the machine is running in combination with the magnet wire or helix F, as commonly employed, substantially as shown in division four."

The respondents, who were assignees of the above patent, commenced an action in Scotland against the appellants to have the patent declared null and void.

Prior publication and user were alleged. Amongst the publications, Clark's specification (4311 of 1875) and Varley's (4905 of 1876) were relied on.

Clark's invention consisted in taking a derived current from the poles of the machine which furnishes the currents to the fixed electro-magnets, and using it for doing the external work required. Improved results were obtained where the work to be done was constant. The application of the invention of "lateral derived currents" to a Lontin machine was shown. In the Lontin machine the armature bobbins were fixed radially on an axis revolving between two fixed electro-magnets. Clark connected each bobbin to a separate "rubber" on the axis or commutator. They could thus be grouped for quantity or tension. One or more of them could be separately connected with the existing fixed magnets. The claim was for the employment of "lateral derived currents" for all purposes where a constant current was required.

Varley's specification described a complicated mode of constructing dynamos. In describing his machine, the following passage occurred :— "Part of the electricity developed by the machine is diverted to

maintain the magnetism of the soft iron magnets, and the remaining portion is used to produce the electric light. There are several well-known ways of doing this, but the method I prefer is to wrap the soft iron magnets with two insulated wires, one having a larger resistance than the other. The circuit of larger resistance is always closed, and the circuit of less resistance is used for the electric light. When the electric light is being produced, the greater portion of electricity passes through the circuit of less resistance, which I term the electric light circuit,' maintaining the magnetism of the magnets and producing the light. When the electric light circuit is opened from any cause, the electricity developed passes through the circuit of greater resistance only, and maintains the magnetism of the magnets."

There was no claim in Varley's specification for series-shunt winding, nor was such winding illustrated, nor were any directions given for carrying it out, and the evidence was conflicting as to whether an ordinary skilled workman could carry out

the compound winding from Varley's description only.

Varley's knowledge at the date of his specification of shunt winding was proved by a rough sketch 1 of his invention that was made in his diary. Across

Sketch from Varley's diary.

the page was written this sentence: "It would probably be better if the cores of the bobbins were made of a bundle of wires and not a solid cylinder."

It was proved that before the introduction of parallel lighting by glow. lamps in 1882 there was no demand for a dynamo producing a current al constant potential, as distinguished from one producing a constant current. Evidence was also given as to the fall of potential in a series-wound dynamo with the increase of external resistance; and in the case of a shuntwound machine, of the division of the current in the two circuits in a ratio the inverse of their respective resistances, whereby the potential was increased when less current was required for lighting purposes.

There was no mention in Haddan's specification of the maintenance of a constant potential; this could only be ensured by regulating the ratio of the resistances of the two circuits round the magnets with regard to the work the dynamo had to do.

At the trial, the Lord Ordinary held that (1) there was disconformity between the complete and provisional specifications, and (2) that the invention had been anticipated by Varley (6 R. P. C. 414).

The diagram here given is reproduced from the original exhibit given to the author by Mr. J. C. Graham.

? The report of this finding is unnecessary; a summary of it is given, ante, pp. 69, 70.

On appeal, the First Division held that the patent had been anticipated ; no decision was given as to the alleged disconformity (7 R. P. C. 436). On appeal to the House of Lords.

Held, that the invention claimed as above in Haddan's specification was disclosed in Varley's, and therefore the patent was invalid.

Per Lord Halsbury, L.C. (at p. 317): "The 'series' was known, the 'shunt' was known, and the language" (of Varley's, as above) "seems to me incapable of any other interpretation than that the patentee" (Varley) "did mean to combine the two previously known systems. If he did, and disclosed the mode of doing it, the novelty of the later patent cannot be supported. I confess I am unable to entertain a doubt that it was so disclosed. What he intended was, I think, conclusively shown by the original rough sketch produced. Distinguished electricians cavil at the mode of its disclosure, criticise the language (which is not, perhaps, the most felicitously chosen), and possibly suggest doubts as to what would have been the fate of Mr. Varley's patent if it had been attacked upon the ground of the insufficiency of the specification; but that is not the question to be determined here. The question is the disclosure of the invention, which consisted in the combination of two known forms or dynamo-electric machines. . . . I think it is certain that neither the one patentee nor the other had any very definite notion of the importance of the invention until a year or two later. The invention of the incandescent light brought into prominence the importance of an even uniform and continuous flow of the electric energy."

Lord Watson (at p. 319): "The appellants' evidence consists of oral testimony by electricians of great eminence, and is directed mainly, if not wholly, to prove (1) that on a fair construction of the specification of 1876 (Varley's) the words relied on do not disclose either shunt or series-shunt winding, and (2) assuming them to do so, that the specification does not contain explanations or directions which would enable a workman of ordinary skill to construct either a shunt or a series-shunt machine. . . ." At p. 320: "The testimony of their witnesses was given upon the footing that in 1876 Clark's invention of the previous year was still unknown, and that those who read Varley's specification could have no knowledge of any system other than series-winding. Upon that assumption it occurs to me that a reader, whether a man of science or skilled workman, would probably have been at a loss to discover what Varley meant, and might not have arrived at either shunt or series-shunt winding with some exercise of his inventive faculty. I am, however, unable to find any good reason for finding that Clark's shunt machine was unknown in the year 1876. It is true that Mr. Brush had never heard of Clark's invention, and also that shunt-winding was unknown to Sir William Thomson before 1879. But it appears to me that Clark's taking out a patent for his invention was, both in fact and law, a publication of it. I do not suppose that every electrician, however eminent, is by necessity personally cognizant of every invention patented within the bounds of his science; and the ignorance of two or more of them

is unavailing to prove that the knowledge of others was equally defective. I cannot therefore avoid the conclusion that, in 1876, Clark's shunt-winding machine had been disclosed to the public, and must have been known to some, if not to all, electricians, and consequently that the controverted passage in Varley's specification ought to be construed on the footing that shunt-winding was known at its date."

"I do not think it necessary to deal with the conflict of testimony as to the sufficiency of Varley's specification for the guidance of a skilled workman. . . . Every patentee, as a condition of his exclusive privilege, is bound to describe his invention in such detail as to enable a workman of ordinary skill to practise it; and the penalty of non-compliance of that condition is forfeiture of his privilege. His patent right may be invalid by reason of non-compliance; but it certainly does not follow that his invention has not been published. His specification may, notwithstanding that defect, be sufficient to convey to men of science and employers of labour information which will enable them, without any exercise of inventive ingenuity, to understand his invention, and to give a workman the specific directions which he failed to communicate. In that case, I cannot doubt that his invention is published as completely as if his description had been intelligible to the workman of ordinary skill." 1

1892. LANE Fox v. KENSINGTON & KNIGHTSBRIDGE ELECTRIC LIGHTING CO., LTD., 9 R. P. C. 221, 413.

Disconformity-Insufficiency-Want of Utility.

In 1878 a patent (No. 3988) was granted to St. G. Lane Fox for "improvements in obtaining light by electricity, and in conveying, distributing, measuring, and regulating the electric current for the same, and in the means or apparatus employed therein."

The provisional specification2 began with the above title and a description of the lamp (metallic leaves or foil) employed. It continued: "The way in which I work a number of these lamps from a single source of electricity is as follows. From one pole or electrode of the electric generator or generators proceeds a large conductor, from which branch out at various points where lights are desired smaller conductors, which again may have conductors branching off from them, and so on. The other pole or electrode of each electric generator is connected with the earth, so that the conductor and its branches and sub-branches will be perpetually in a state of electric tension, tending to develop currents in every direction to the earth. One pole of the electric lamp is connected with the earth, and this may be conveniently effected by means of gas or water pipes, where such exist, so that wherever

1 This paragraph was quoted and followed by Lindley, L.J., in Savage v. Harris, 13 R. P. C. 368.

? Only those parts which are material for the present purpose are here given.

the circuit is complete between the earth and any one of these branches a current of electricity will pass through the thin leaf of metal, rendering it incandescent, and so produce light." The system of measurement was next described; and the specification continued:-"The electromotive force of the electric conducting mains should be kept as nearly as possible constant, at, say, 100 volts or B.A. units of E.M.F. A number of Plante's (lead and sulphuric acid) cells joined together in series between the main and the earth will serve as a kind of reservoir for electricity." The conductors are next described, then :-" In order to keep the E.M.F. in the mains constant, it is desirable to have in the first place several generating machines; next, it is necessary to have some regulator, such as that about to be described." The regulator consisted of a quadrant electrometer connected with the main and earth "in the usual way." The needle, on coming into contact with fixed pegs, would complete local circuits, and so actuate levers acting on valves, thereby increasing or diminishing the supply of steam to the generating engines.

The complete specification was for "improvements in [obtaining light by electricity, and in conveying], distributing, [measuring], and regulating the electric current for [the same], obtaining light by electricity and in the means or apparatus employed therein." The lamp was first described, consisting of a platinum or platinum alloy wire or leaf. Then came the general system of distribution as mentioned in the provisional and illustrated by Fig. 3, A being the generator, and the conductors being shown by the lines, terminating in lamps, from which the "earth" wires (not shown) led to "earth." The mode of connecting them to gas or water pipes was described. The measuring apparatus (a shunted voltameter) was also described. "The E.M.F. of the electric conducting mains should be kept as nearly as possible constant, say at 100 volts or B.A. units of E.M.F. A number of secondary batteries, such as Plante's (lead and sulphuric acid), such batteries being joined together in series between the main and the earth, will serve as a kind of reservoir for the electricity. The cells should have a very large conducting surface, and there should be several batteries connected up at various points of the mains, so that by increasing the E.M.F. during the hours when not much electricity is being used, they will become charged and the electric force will be stowed up in them, so that a sufficient supply will be available when the E.M.F. falls, owing to the draft from the mains when the force is most used and needed. The number of cells in each of these batteries will depend on the E.M.F. of the mains."

"Fig. 5 is a diagram representing a secondary battery joined up between the main and the earth for the purpose above described. E indicates earth, and lamps. . . . In order to keep the E.M.F. in the electric mains

1 Only those parts are inserted which are necessary to appreciate the decision. The amendments made by disclaimer are shown :-the words in square brackets were omitted, and those in italics inserted.

Figs. 3 and 5 are diagrammatic, and are here given.

3 A description of the conductors were here omitted by disclaimer.