being cut to receive the band, without which they alleged the rings would not remain on the bobbins.

The Court of Appeal held that the improvement in question was not such an advance upon the methods of the two earlier specifications as to constitute a patentable invention; also that the third claim was for the ferrule per se apart from the fastening on the bobbin, and that it was not new. The patent was held invalid.

On appeal to the House of Lords it was held that the specification claimed as an invention the fitting on of the rings without grooves, that there was no evidence to prove that this had been done, by the inventors or any one, so that the rings would not come off when being used. The appeal was dismissed.

Lord Halsbury, L.C. (p. 14), discussed the nature of the question at issue and the nature of the invention, quoting those portions of the specification given in extenso above,1 and continued (p. 15 (48)): "If that had been proved to be practicable, I confess for myself I thought that it was a very ingenious and meritorious, although it seemed only a simple expedient, the turning in a ring of a sort of ferrule which probably everybody's umbrella has, accomplishing those objects which are set forth in the specification by very simple and effectual means. My Lords, when I find out now what the fact is it appears to me that there is no foundation for the whole of the allegation that the thing purporting to be done has ever been done. . . .” In the Court of Appeal counsel (p. 16 (1)) "very sternly protested that the thing suggested to be done by the patentee could not be done at all, and never had been done, and when an opportunity was given to those who were in favour of the patent to produce a single specimen which would prove the application of the patent in that manner, and so prove that it had been done, there is an absolute failure to prove anything of the sort. . . ." P. 16 (56): "My Lords, the result is that in this case I think the patent itself has shown no invention and no sufficient utility. It is very rarely, I think, that the question of utility is important; the word 'utility' does not occur in the statute, but I mean having commercial existence as a process of manufacture."

Per Lord Davey (p. 20 (12)): "I concur that we have not had brought before us any single example or instance in which a bobbin has been made in accordance with Figs. 2 and 3 of the plaintiff's specification of 1895, and that there is no evidence before your Lordships that the patent is capable of being worked, or that the invention which I think is claimed by claims 1 and 2 is capable of being applied in a practical or useful manner-at any rate, to any extent. It may be that in some soft woods it would be possible to apply it, but it appears from Mr. Greenwood's evidence that they have found it necessary (generally I think was his expression) to make a groove to receive the thickened edge before applying the pressure. The patent is not confined to any particular kind of wood, but on the face of the patent it

1 Ante, pp. 463, 464.

is made to apply to all kinds of wood of which bobbins are usually made. I think the qualification ought to be put in 'of which bobbins are usually made.'

"My Lords, I think, therefore, that the patent is bad, either from want of utility, or, if it had been pleaded, for want of sufficiency of specification, and it fails on that ground.”1

1903. CHAMBERLAIN AND HOOKHAM 7. MAYOR, &C., OF BRADFORD," 2 20 R. P. C.

Construction-Combination-Subsidiary Claim-Equivalents.

A patent was granted (No. 4225 of 1887) to G. Hookham for an invention of "improvements in electricity meters, parts of which improvements are applicable to dynamo-electric generators and motors."

The complete specification was twice amended, on the 14th February, 1889, and on the 14th August, 1895.

The specifications are as follows:-3

"My invention consists of the improvements hereinafter described in electricity meters, parts of the said improvements, as hereinafter pointed out, being also applicable to dynamo-electric generators and motors.

"I will describe my invention as applied to an electricity meter. "My said electricity meter consists essentially of an electro-motor with constant or nearly constant field, the armature carrying the current to be metered and an electric brake consisting of a mass of metal in the form of a disc, cylinder, or other figure of rotation, rotating in a magnetic field in such a manner as to have' eddy' or so called 'Foucault' currents generated in it. When all other work done by the motor is negligible compared with that done against 'eddy' currents the speed of rotation of its armature is directly proportional to the armature current.

"The electro-motor may be of any of the ordinary forms now in use. It may, for instance, have a drum, ring, or disc armature. Or it may consist of a simple solid disc or cylinder rotating between magnetic poles. In the latter case, however, I may use two thicknesses of metal in the disc or cylinder, the one carrying the current to be measured being insulated from the other except near the centre. And in order to confine the current to a narrow field the said disc or cylinder may be slit in directions at right angles to the motion in the field; or instead of a disc or cylinder so slit, insulated wires or metal strips may be used.

"The electric brake may be formed by the armature itself, or it may be attached to the armature so as to rotate in the same field, or it may be

1 As to the connection between "utility" and "sufficiency," see ante, pp. 80-83.

2 This abstract is prepared from the original documents and from hearing the case when this work was in the press. The author is indebted to Messrs. Ashurst, Morris, Crisp & Co. and Messrs. Field, Roscoe & Co., for the drawings here reproduced.

3 The provisional is repeated in the first portion of the complete.

independent of the armature, and rotate in a separate field; or a separate brake may be used in addition to an armature brake.

"In order that other work done by the motor may be very small compared with the work done on the electric brake, special means to reduce friction are adopted. If the axis of the motor armature is horizontal, the spindle is supported on anti-friction wheels; and if vertical or nearly vertical, on hardened points, and in both cases I use mercury contacts or commutators where practicable.

"If the spindle of the motor is horizontal I form a double or divided

commutator consisting of two sets of insulated spokes or projections placed side by side, each set dipping into a mercury trough, the mercury troughs being connected one with each terminal of the machine. Each commutator spoke is put in connection with the one opposite to it on the other half of the double commutator, so that the mercury troughs, though both on the same side, act as ordinary brushes act when placed on opposite sides of the commutator. If the spindle is vertical I take advantage of the high surface tension of mercury in virtue of which it may be made to stand above the level of the vessel containing it. The ends of wires or metallic

strips from the vertical armature can thus cut the mercury without touching the vessel.

"When I use a motor consisting of a simple solid disc or cylinder, I may, in order to economize magnetizing force, corrugate the disc or cylinder

in concentric rings and form the magnet poles to correspond, and thereby not only lessen the resistance of the non-magnetic space, but also increase the efficiency of the driving current. If in any case it is found impracticable to render friction or other disturbing causes inappreciable, I may 'compound-wind' the magnets or armature of the motor or, if it is separate, of the electric brake.

"In cases where iron is used in the armature or the electric brake, I may

so dispose the magnets as to counteract or partially counteract gravity, and thereby lessen friction. For alternating currents the magnet cores, and if of iron the armature core, must be finely divided into wires or metal strips. "The rotations of the axis of the armature of the meter are registered by means of counting apparatus of an ordinary type.

"The double commutator and the corrugation of the disc or cylinder

and pole-pieces hereinbefore described are applicable to dynamo-electric generators and motors."

The specification (up to this point a repetition of the provisional) continued by giving a description of the drawings in detail. Fig. 1, representing a side elevation of an electricity meter "constructed according to one form" of the invention, Fig. 3, an end elevation at the commutator end, and Fig. 5, representing the armature in elevation, are here reproduced. The latter is thus described :

"The armature consists of a series of metallic sectors marked respectively 1 to 16, both inclusive in Fig. 5. These sectors make up a circular disc with radial slits, by which slits the said sectors are electrically insulated from one another. These sectors do not extend to the axis a of the machine, as seen in Fig. 5. The said sectors are carried by the circular