constant, it is desirable to have in the first place several generating machines, also a number of reservoir batteries, as before explained; [next it is necessary to have some regulator such as that about to be described].” 1 quadrant regulator was disclaimed and its description struck out.

The claim in the amended specification was for "the employment as described of secondary batteries as reservoirs of electricity in combination with a mode or system of distribution such as is hereinbefore explained.”

In an action for infringement against the defendants the following facts, inter alia, were proved :

That Planté cells, when discharging, had a smaller potential difference between their terminal plates than when being charged, hence they could not act as automatic regulators of potential in the mains.

That they were useless unless used with a switch, so that the number of cells in the battery could be varied with the rise or fall in potential during charging and discharging. Without a switch the pressure necessary to charge the batteries would break down the lamps. This was illustrated by the curves here reproduced. From them it appears that if the battery

Curves by Prof. WE.Ayrton F.R.S.

-Time of Charging in Hours---

--

---Time of Discharging in Hours---+ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 14 1 2 3 4 5 6 7 8 9 10 # 12 13 14 14 į

(say of 50 cells) be arranged to discharge at 100 volts, it must be charged at a pressure from 105 to 115 volts, which the lamps would not bear.

But if that difficulty were overcome, it was proved that there would be considerable irregularity both in pressure and current during the discharge, so that the battery could not act as a regulator. The amount of this irregularity is shown by Prof. Kennedy's diagram given below.

That Planté cells were well known in 1878, and had been used for storage

1 These words were struck out by disclaimer.

2 In this diagram produced at the trial the descending curve was continued further. It was originally published by Prof. Ayrton and Messrs. Lamb and Smith to illustrate their paper on "The Chemistry of Secondary Cells." The breaks at B, C, and C' were due to the stoppages in an experiment to remove certain test plugs. The change of potential of the battery in action is according to the continuous curve. See Vol. XIX. p. 660 of The Journal of the Institution of Electrical Engineers.

in connection with arc lighting, but not in connection with dynamos for incandescent lighting.

That in 1878 no successful incandescent lamp had been invented. Nor was it known that in large districts the earth could not be used as a return conductor-the term "earth" was technically used for return conductors.

VOLTS

(130

125

120

115

Diagram 1 by A. KENNEDY F.R.S.

Showing irregularity of Potential & Current from a Battery of
60 31 Pl. cells discharging with variable external Resistance
Potential at end of Previous Charge-154.8 or 2.58 per cell.

108.3

Volts per 50 cells

7 Hours

The patent was held invalid at the trial on the grounds of disconformity and insufficiency, and the opinion expressed that otherwise it was new, was subject-matter, and had been infringed (9 R. P. C. 221).

Both parties appealed.

Held, by the Court of Appeal

That without further invention or experiment as regards "switching" the invention was useless for the purposes described by the patentee.

That the specification was insufficient, owing to the want of such directions as would enable a constant pressure to be maintained in the mains.1 The patent was therefore invalid.

That the invention claimed in the amended specification (regulation by batteries) was different from that described in the provisional (storage by batteries and regulation by regulator).2

This follows from the preceding finding. It is looking at the same matter from a different point of view.

2 This finding (at p. 419) was not enunciated until the patent had been declared invalid. In coming to the conclusion that the amended complete specification was disconform to the provisional, the learned Lords Justices followed the decision of the Court of Appeal in Gaulard & Gibbs' Patent (6 R. P. C. 215), in which case there was a strong analogy as to the facts, without noticing that the House of Lords did not approve of the

Per Lindley, L.J. (p. 416): "An invention is not the same thing as a discovery. When Volta discovered the effect of an electric current from the battery on a frog's leg, he made a great discovery, but not a patentable invention. Again, a man who discovers that a known machine can produce effects which no one knew could be produced by it before, may make a great and useful discovery; but if he does no more, his discovery is not a patentable invention:-Britain v. Hirsch, 5 R. P. C. 232; Harwood v. G. N. Ry. Co., 11 H. L. C. 654; Horton v. Mabon, 12 C. B. N. S. 437 ; Saxby v. Gloucester Wagon Co., 7 Q. B. D. 305. He has added nothing but knowledge to what previously existed. A patentee must do something more: he must make some addition, not only to knowledge, but to previously known inventions, and must so use his knowledge and ingenuity as to produce either a new and useful thing or result, or a new and useful method of producing an old thing or result. On the one hand the discovery that a known thing-such, for example, as a Planté battery-can be employed for a useful purpose for which it has never been used before is not alone a patentable invention; but, on the other hand, the discovery how to use a thing for such a purpose will be a patentable invention if there is novelty in the mode of using it, as distinguished from novelty of purpose, or if any new modification of the thing, or any new appliance is necessary for using it for its new purpose, and if such mode of user, or modification, or appliance involves any appreciable merit. It is often extremely difficult to draw the line between patentable inventions and non-patentable discoveries, but I have endeavoured to state the distinction as I understand it, and so far as is necessary for the purposes of the present case. I have, of course, been guided by the previous decisions on the subject, and especially by Harwood v. G. N. Ry. Co., which is the most instructive of them all." 1

At p. 417: ". . . The utility of the alleged invention depends not on whether by following the directions in the complete specification all the results now necessary for commercial success can be obtained, but on whether by such directions the effects which the patentee professed to produce could be produced, and on the practical utility of these effects. Can it be said that the invention as described in the amended specification was, in 1878, a practically useful addition to the then stock of inventions? To judge of utility, the directions in the amended specification must be followed, and, if the result is that the object sought to be attained by the patentee can be attained, and is practically useful at the time when the patent is granted, the test of utility is satisfied. Utility is often a question of degree, and always has reference to some object. Useful for what?' is a question which must be always asked, and the answer must be, useful for the purposes indicated by the patentee."

finding of disconformity by the Court of Appeal in that case (ante, p. 64). An inventor should not rely too much on this being an example of disconformity.

As re-stated by Lindley, L.J., in Moser v. Marsden, 10 R. P. C. 358, and followed by Smith, L.J. (ibid., p. 363). Followed in Pirrie v. York St., &c., 11 R. P. C. 438, 453, 455; Thierry v. Rickmann, 12 R. P. C. 427; and Acetylene Ill. Co., Ltd. v. United Alkali Co., 20 R. P. C. 173.

1892. GADD & MASON V. MAYOR OF MANCHESTER, 9 R. P. C. 516. Disconformity Inventive Ingenuity-Prior Publication.

In 1888 a patent (No. 18119) was granted to Messrs. Gadd & Mason for "improvements relating to the construction of gasholders."

1

The specifications were as follows:

"The improvements relate to the construction of gasholders, and have for object the supporting of the same in their working position, in such manner as to enable the external or upper guide framing hitherto employed for that purpose to be dispensed with, and yet to give the requisite stability; although such, or a modified form or framing, may be employed in connection with the improvements herein described, when desired.

"To accomplish this, and to effect our improvements, we fix round the face of the tank or well a series of vertical guides, which are constructed in the form of racks, or mechanical equivalents therefor, (such as vertical screwshafts of coarse or quick thread, or vertical endless chains or bands passing over and betweeen pulleys or wheels at or near the top and the bottom of the tank or holder, as the case may be). At corresponding intervals round the lower curb or ring of the holder we mount on suitable shafts or studs, pinion, mitre, or other toothed wheels or mechanical equivalents therefor (such as notched wheels, or in some cases plain wheels or pulleys), which gear into or with the racks or equivalents aforesaid.

"These wheels are, by preference, all likewise geared together, in such manner that when one is caused to turn, the whole will turn therewith and to the same extent. By which means, if the holder carrying or connected with these geared-up wheels moves upwards or downwards, it will be sustained in the same relative position at all heights.

"The like result is also obtained by fixing the vertical racks, or equivalents as aforesaid, to the outer face of the holder, and the pinion, mitre, or other wheels round the top of the tank; and in like manner the method may be extended to telescopic holders.

"The wheels which take into the guides may be geared together either by shafts, intermediate between and turning in suitable journals; or by means of intermediate wheels in train [round the circle]; or by plain-chain or rope or link-chain gearing; and instead of the whole of the wheels being geared together, portions thereof may be geared as a modification.

"Other variations in detail may be made without departing from the peculiar character of the invention, which consists in connecting, by means of torsional or tensional gearing, a number of points round the bottom curb of a

The specifications are here shown together. The provisional specification can be read by omitting all the passages and words in italics, and including those words in square brackets down to the beginning of the description of the drawings. To read the complete include the words in italics and omit those in square brackets. The new matter constituting the alleged disconformity will be thus seen at a glance.