patentee's invention as described in his specification and illustrated in his drawings.

But this rule of construction of patent claims is entirely subordinate to the fundamental and controlling rule that a patentee's broadest claim can be no broader than his actual invention, no matter how it may be expressed or what other claims his patent may contain. When a patentee has fully and clearly described his actual invention in the specification and drawings of his patent, and has fully covered that invention by the broadest claim to monopoly which the law will allow him, he cannot then, by merely including in his patent a more broadly or more vaguely stated claim, cover and monopolize something more than and different from his real invention. Now, while it is a very common thing for the courts to construe a claim of a patent by reference to some other claim of the same patent, and to apply the rule of construction to which plaintiff refers, it is equally common for the courts to wholly disregard and ignore such rule of construction whenever it comes into conflict with the fundamental and controlling rule that a patentee's claim can be no broader than his actual invention, and they have not hesitated to hold a claim invalid where it could not be restricted by construction to the patentee's actual invention as disclosed in the specification and drawings of his patent.

That is what this court did in the Hillman Case, and what was done by the Circuit Court of Appeals of the Eighth Circuit in the Jewell Filter Case.

It is also to be noted, however, that there are differences between claims 29 and 30, sufficient to so distinguish them, and to hold that both are valid. Claim 29 counts on control of the "carrying mechanism" by the "next higher actuator," while claim 30 counts on delay of the "carrying" by the "actuator of a higher denomination." It will not do, in this difficult and intricate matter, to make the absolute statement that the fifth element of both claims is identical.

[3] Defendant's Mechanism. It has been stated in the opinion that defendant's mechanism, which it is now necessary to describe, does not include means for a delayed carry, or any equivalent mechanism. The object of both constructions is to enable one complete revolution of a lower order numeral-wheel, say the units, to transmit to the next higher or tens wheel a one-step carry, or one-tenth revolution. Each numeral-wheel (except the first and last) has a dual function. Each is a lower order wheel to its next higher neighbor, and a higher order wheel to its next lower. Each must transmit the carrying impulse to the next and receive it from the lower one, and in so doing neither must interfere with the other.

In order to do these things rapidly and correctly all the mechanism must be connected like a watch in the most exact and perfect way, and within a very small space. Between the units and tens wheels (also the tens and hundreds, etc.) there is placed a set of small cogwheels or pinions which wind up a spring in order to make the one-step carry. There is also a cam, an escapement, lever, catch, etc. So when the units wheel turns from 1 to 9 it winds up the spring ready

to be tripped when the wheel reaches the cipher position and to turn the tens wheel one step. Some device, also, must be arranged to prevent the one step carry being smothered or swallowed up by the larger movement of the next lower wheel, as described by Mr. Felt in the language quoted. Felt does this by a ratchet and pawl construction and the delaying latch 73 controlled by the next higher actuator, and defendant by the transmission mechanism referred to and the planetary or differential gearing shown in the accompanying cuts.

DEFENDANT'S DEVICE.

HIGHER ORDER ACTUATOR, BACKSTOP, DRIVING PINION, PINWHEEL AND OVERRUNNING PAWL.

The foregoing drawings represent a planetary gear and some additional devices such as the higher order actuator, driving pinion, pinwheel, backstop and pawl to prevent overrunning, all attached to a higher order numeral-wheel, the actuator shown being the "next higher" one referred to in claim 29. The sun gear is normally stationary, is not turned by the movement of the actuator, but only by the carrying spring attached to the transmission devices, and wound up by the movement of the lower order wheel not shown.

It may be difficult to describe the characteristic motion of a planet gearing, but it is just like the differential of an automobile. Its fundamental principle is that a cogwheel turned by two other cogwheels moving simultaneously will take on the sum of both movements. The

planetary movement has long been well known, and is an accelerated motion due to force transmitted from two points into one. That is, when the driving pinion alone moves the planet gear turns. When the sun gear alone moves the planet gear also turns. When both driving and sun gears move together the planet gear takes on a more rapid motion as the result of both, and the planet gear is the last step in the train which makes the carry by turning the higher wheel one step. Now as the lower order wheel through the transmission and spring turns the sun gear, and the higher order actuator turns the driving pinion which in turn drives the higher order numeral-wheel, it is obvious that the difficulty described by Mr. Felt as the loss of carry by the swallowing up of one movement by the other cannot occur, because the planet gear will transmit to the higher wheel the motion it receives from the sun gear just as well when the numeral-wheel is turning from a key impulse given by the actuator as it will when the actuator is at rest. When the actuator is making its rising or driving stroke it will be seen that the planet gear is being carried idly around the sun wheel by the internal gear N. If at this time a carry comes over from the lower wheel, by the spring turning the sun gear contraclockwise, this motion of the sun gear will be transmitted through the planet wheel by the internal gear N to the numeral-wheel N1, and move it one step in the opposite or clockwise direction. Carry-Control by Next Higher Actuator. Claim 29 counts on "means whereby the several carrying mechanisms may be temporarily controlled by the next higher actuators." So a further question that may be thought material is whether defendant's carrying device is within this claim. And since claim 29 is clearly valid because it was new to control the carrying operation by the next higher actuator, it will conduce to a better understanding of the case to inquire whether or to what extent defendant uses the temporary control of claim 29, and if so whether defendant's carrying device is an equivalent of plaintiff's.

The notion of control of carry in the Burroughs' device is based upon a fundamental principle applying to all differential gearing, which is that a pinion or cogwheel placed between two other cogwheels cannot turn either one unless the other is either held stationary or driven in the proper direction. Thus the driving pinion I in the first cut must be held stationary or be moving forward at the instant that the planet wheel is turning the numeral-wheel N1 by the influence of the sun gear M2. The second cut shows how this driving pinion is normally held from backward motion by the backstop pawl K when the column-actuator F1 is making its downward movement, also how the backstop will ride over the pinwheel when moved clockwise by the upward or driving stroke of the actuator. Those who understand automobile operation will know why the driving pinion cannot be allowed to turn backward while the planet gear is being operated by the sun gear. When a car is coasting down hill, in gear, but with the spark turned off, the movement of the hind wheels is propelling the engine through the differential and main shaft. During this operation, if one of the hind wheels should leave the ground while rounding a curve.

the engine would stop, because it is absolutely necessary that both wheels shall be on the road, or the differential pinion, corresponding to the planet gear, will idle about the large gear wheels connected with the rear axle shafts in the differential, and exercise no driving power on the main transmission shaft. The same thing happens if one wheel of the car is lifted from the ground and turned by hand. This will operate the engine if sufficient force be used, but if both wheels are off the engine will not turn over. This illustrates the point that the driving gear must either be stationary or held from backward movement while a carry is being made.

Bearing this in mind, the cut may be explained by saying that the actuator shown is the "next higher" one in mesh with a gear wheel not shown, and which is supposed to be rising and making its driving stroke at the exact instant when a carry is coming over from the lower order wheel. In the cut, however, the parts are shown in their normal, inactive position. The pinwheel and driving gear are held from backward movement by the backstop K pressed against the pinwheel by its spring, and from forward movement by the actuator itself. The driving gear and pinwheel are rigidly connected.

Suppose now the actuator is depressed by its own key-movement. The latch J will be pulled by its spring downward away from its registry with the pinwheel, and thus allow forward movement of the pinwheel and driving gear, but which are still held from backward movement by the backstop K. So if a carry is coming over during the descending or idle stroke of the actuator, it will be properly made, because the driving gear is "on the ground," held immobile by its backstop. But when the actuator begins its upward or driving stroke the backstop, by the turning forward of the pinwheel, is made to slide over the cogs or pins and thus prevented from holding back the driving gear. Of course such gear cannot be held back and go forward under the lead of the actuator at one and the same time. It is at this instant of a rising actuator that the latter is said to temporarily control a carry if one then happens to be coming over.

By referring to the diagram the operation of a driving or rising stroke may be clearing understood. The actuator forces the backstop out of commission and itself steadies and holds firm the pinwheel and attached driving pinion by pushing them forward. It is like the pilot assuming the wheel on an incoming steamship; he takes control from the helmsman and assumes it himself. So it is plain that it is accurate to say that when both K and J are out of commission during the driving stroke the only thing which can steady the driving gear is the actuator, and if at this instant a carry is made the actuator, by pushing the driving gear forward, prevents it from going backward, and so in a sense "temporarily controls the carrying mechanism." But this is manifestly quite a different control from that positive prevention of a stroke which occurs when plaintiff's latch 73 is made to absolutely tie up the carrying mechanism until the rising actuator stroke is completed.

We have not lost sight of defendant's argument that the Burroughs' higher order actuators do not prevent loss of carry, but in that con