MISCELLANEOUS.

THE THEORY AND DESIGN OF THE CLOSED COIL CONSTANT CURRENT DYNAMO.—III.—(Concluded.)

BY PROF. HENRY S. CARHART.

In the second method the overlap of the brushes must be inversely as the induction in a coil under the brush in different parts of the field, for the presence of the pole of the armature at any point reduces the induction. This point is a complicated one and needs further experimental study. But in the third class of machines the overlap of the brush is constant and the field is not weakened by cutting out coils on small load. Neither are the pole faces cut away to produce uniform induction. Attention is given to the thickness of the pole pieces so as to avoid unnecessary crowding of the lines of force toward the central portions. It is also desirable to avoid thinning the polar horns lest they become saturated.

The author then spoke of the old Sperry machines with internal pole pieces, and gave the results of some investigations made by him upon this type and also upon the old Gramme machine, from which he arrived at the conclusion that for practically sparkless commutation it is not necessary that the induction near, but under the brush shall be a constant. The effective means by which, with constant current, the brushes can be set in any plane round the commutator cylinder is the reactive effect of the armature. This fact is brought out quite clearly by plotting the integrated potential differences between the upper or positive brush and the third movable one as ordinates to a horizontal line.

The data are the same as were employed to plot the first curve in Fig. 1. If Fig. 2 is examined a decided flattening in the curve will be found at 180 degrees, the position of the negative brush. The same flattening may be seen at 0 degrees. All curves, plotted with data obtained at different loads, show the same diminution or stay of the inductive process near the poles of the armature. The armature at these points paralyzes the field. As the poles of the armature move round they sweep away the lines of force of the field, and only enough remain to produce an E. M. F. competent to offset the E. M. F. of self-induction and, in addition, cause the newly directed current to grow to its normal value as the coil passes out from under the brush.

This reactive power of the armature may be utilized to effect approximate regulation for constant current without brush-shifting. But for this purpose the load cannot be a maximum. The poles of the armature must be far enough forward to produce increase of magnetic leakage.

The conditions requisite for sparkless commutation of a constant current machine are quite clearly defined. The self-induction of the short-circuited coils must nearly balance the field in all positions of the brushes. The author then quoted Mr. Esson and Prof. Ryan as saying that the brushes must be kept under the pole faces in order not to enter the weakened fields between the pole corners, and stated that he did not consider this condition absolutely essential, since at maximum E. M. F. the brushes may be moved through a considerable angle without appreciable change in sparking. He dwelt upon this subject at considerable

1. See THE ELECTRICAL ENGINEER, Jan. 24.

2. London Electrician, March 31. 1890.

3, Proceedings of the Am. Inst. Elec. Engrs., Vol. VIII, p. 465.

length and supported his statement by data from machines in actual operation.

In conclusion the author said: The design of closed-coil Gramme rings for high potential arc lighting has thus far been limited to the two-pole type of field-magnet. This involves the maintenance of higher speed than engineers find desirable. The conditions of present practice and the requirements for the immediate future demand a new departure in this class of dynamo design. All indications point toward a multipolar machine of about 50 kilo-watts capacity and slow speed. The armature will contain a liberal amount of iron, much larger than would be found desirable for constant potential machines. Such a dynamo is already in demand, and it will find an immediate field for the lighting of large cities.

THE ELECTRICAL TRANSMISSION OF POWER FROM NIAGARA FALLS.-VIII.

BY PROF. GEORGE FORBES. (Discussion.)

MR. ALEXANDER SIEMENS said it was only right to the Commission who asked for the tenders that he should put the matter from a different point of view from that represented by Mr. Ferranti. He had not the conditions upon which the tenders were given. He (Mr. Siemens) had the pleasure at the time of speaking to the President of the Commission, who explained to him that the conditions were to be, that the different competitors were to send in detailed designs, and if successful, superintend the construction of the machinery in America for a commission of 21⁄2 per cent. or 5 per cent., he forgot which. Under those conditions they competed, but did not send detailed designs, and as a matter of course, were excluded from the prizes. But he was perfectly certain that nobody who read the conditions under which they tendered could say that it was not from the beginning the intention to construct the whole of the machinery in America. He did not think any question ought to arise about being able to send a current of 20,000 volts through underground cables. He, for one, would be perfectly ready to supply cables that would carry 20,000 volts. Such cables were in daily use at the Frankfort Exhibition, having been supplied by his firm for connecting the transformers in the machinery hall to those in the Main annex; the normal working pressure was 20,000 volts, the cables having previously been tested to 40,000 volts. Another point which had been insisted upon was that it was quite out of the question to think that a continuous current could serve for such a transmission. Well he was not so sure about that. Their own project for the Niagara transmission was for continuous current, using machines and motors in series. He was not sure that the Cataract Construction Company would not be converted to the continuous current before they had done.

MR. S. EVERSHED said one speaker had spoken of the effect when large solid conductors were used; but Prof. Forbes did not say he was going to use large solid conductors, and he (Mr. Evershed) did not doubt that he would not do so. He showed in his diagram of the subway something which might be taken to be laminated strip conductors, so that the skin effect, elaborately discussed by Lord Kelvin, would not have any prejudicial effect. But there was one effect which would come in, and it was of vastly more importance, and that was the induction between the conductors, whether solid or laminated. It was easy to work out what the back electromotive force of induction would be for any pair of conductors run at any given distance apart, and he had worked out a few cases, taking the conductors to be 6 in. apart, or 12 in. or 3 ft. He also took the density at 333 amperes per square inch, which he understood the author proposed to use. He found that there was one great argument for using a low frequency as possible, namely, the enormous inductive drop in the lines if run at the 100 periods of Mr. Mordey. If they had mains of 3 sq. in. in section, as Prof. Forbes would have, and placed those mains 6 in. apart, if they ran at 100 periods they would have an inductive E. M. F. of 880 volts per mile. Running at 25 periods this was reduced to 192 volts, while the resistance drop was 27 volts. On that ground alone Prof. Forbes appeared to him to have an unanswerable argument in favor of low frequency in that particular case. The only other point he desired to refer to was the quostion of coupling in parallel. He wanted, if possible, to get Prof. Forbes to tell them distinctly what were the uses of an artificial load in coupling machines in parallel.

MR. CROMPTON said there had been an important omission in the discussion. The question which was of real interest to them was, What would be the cost of power to the users in Buffalo or in the more distant towns? How would it compete with the cost of power produced in those towns? That was the point that would interest him most. He should think many engineers like himself had had such schemes on a smaller scale brought before them, and in the large proportion of cases they were reluctantly obliged to abandon them because the interest on the cost of the plant was so great as to overwhelm the advantages of

using water power. He had been forestalled in many of the remarks he would have made by Mr. Ferranti. The barefaced attempt to pick the brains of the world and then to utilize the information gained for the benefit of the American manufacturers was a thing to be admired. He was sorry to say that similar attempts were often made in England; he spoke feelingly. There were many who had spent their blood and treasure in the perfecting of the mechanical details and the other details of electrical machinery, and who could not get any reward for their labors simply because no system of patent laws could cover every little detail of design. The regular modern habit was for the last comer to pick the brains of the world, so they must not blame the Americans, who were only doing on a large scale what had been done so often before on a small one. With regard to the culvert he would not like to be in that culvert when 20,000 volts were going on. If an arc started at one end of that culvert it would go right up to the other end, the whole eighteen miles, in a very short time. Prof. Forbes was going to use porcelain insulators, and he would ask him if he had made experiments to know what the insulating power of porcelain was. What was good enough for electric telegraphs was not good enough for underground work, and failures had been made by those who without sufficient trial had adopted the material used for aerial insulators for underground work. They had made great improvements, and had now got a material that carried 200 volts satisfactorily; whether they would ever get a material which would carry 20,000 volts was beyond him at present. Oil insulators were supposed to be a great remedy, but he thought there were many there who would agree with him after a long trial that they were entirely useless. He did not think continuous currents had been condemned on sufficient evidence. It was useless for people to get up in that room and say there were no difficulties in the matter of "parallelizing❞ alternators. Grave difficulties did exist, and although Prof. Forbes might minimize them, and probably would, by his low frequency he would find he had not then got over the great problems that would arise. He did not agree with Mr. Ferranti that 40 periods were good enough to produce good electric lighting. He had seen many of Ganz's stations at 42, and the arc lighting was disgraceful.

MR. WEEKS asked Prof. Forbes whether his circuits were equally divided on either side, with the lead on one side and the return on the other. Prof. FORBES declined to answer this question.

MR. MAVOR said it would be interesting if Prof. Forbes would describe the method proposed for ventilating and drying the tunnel. This was a matter of the greatest importance, as constant atmospheric conditions in such a subway were most difficult to maintain. It was notable that the most severe criticism of the scheme for carrying high-tension currents along bare conductors in a culvert came from the principal exponent of the similar method of conducting low-tension currents. The author has said in his Paper that Mr. Tesla has clearly demonstrated the rapid deterioration of solid insulations with currents of high frequency, but many of these effects are also present with currents of low frequency at an equally high voltage.

Major Gen. WEBBER said they ought all to feel the greatest sympathy with Prof. Forbes in connection with this Paper from one point of view. He had brought before them a Paper referring to work not yet carried out, and in criticizing the account he had been good enough to favor them with they should remember that it was inevitable that modifications would have to be made in carrying out that work.

MR. KAPP gave an abstract of a communication from Mr. C. E. L. Brown. Mr. Brown advocated a higher frequency than Prof. Forbes, and with regard to running in parallel said he had been unable to detect any difference between low frequencies such as 15 and up to 100. It was astonishing that even at the present day so much was still said of the difficulty of running alternators, single or multiphase, in parallel. He had run machines of very different types in parallel under the most different conditions, and had never found the slightest difficulty; indeed, he had come to the conclusion that the coupling of alternators in parallel was as easy as, if not easier than, that of direct machines. To adopt the two-phase system using four wires seemed to him a good arrangement, and judging from his own experience none but good results could be obtained. It certainly seemed remarkable, considering the number of designs sent in, many of which were extremely good, that Prof. Forbes should have decided upon about the worst arrangement possible for his machine. He could not imagine a more inconvenient arrangement than the magnetic wheel revolving outside the armature, so that it was impossible to get at the machine while in motion, whilst losing entirely the ventilating ‹ffect of the revolving wheel for the cooling down of the armature.

FUNNY LEGISLATION.

A member of the New York Legislature has introduced a bill requiring the insulation of all electric wires used for street railroad purposes. By last reports, he was still at liberty.

ECONOMY IN THE USE OF TRANSFORMERS.1

BY P. J. MCFADDEN.

A transformer is nothing more than a dynamo without moving parts and is therefore no exception to the rule that it works best when loaded up to its rated capacity. In selecting a transformer for a given customer, the central station superintendent will too often install one capable of supplying the total number of lights for which the house is wired. In some cases this cannot be avoided, but in houses wired, say, for 40 to 50 lights it will seldom be necessary to put up a transformer any larger than a 30 lighter, and right here I would say that a transformer of a whole size smaller can often be used if the superintendent would take the trouble to consider the case of the particular customer in question. The neighborhood, the size of his family and their habits relative to the probability of entertainments involving the burning of nearly all the lamps in the house, would all with a moment's consideration, determine sufficiently closely what the maximum load would be.

But is it always necessary to install a transformer for every individual customer? Are not some of your stores or even in some cases your residences, so bunched that one transformer could be made to do for several; and if so would you not, if necessary, go to a little trouble with your secondary wiring to accomplish this? Even the bunching of, say, three moderately large transfor mersto serve four or five consumers where one or at most two are likely to have a large load at one time and where this comes so seldom as to make it expensive to put up for each of them a transformer capable of taking that load, while a step in the right direction, is seldom good practice for if the primary fuse of one should blow them out not only does the secondary of that transformer (which is now dead, as far as its capacity to give out current is concerned) become a load upon the other two, but also the load of lamps it formerly carried must now be borne by the others. When this is the case the fuses of the other two will be likely to blow and the whole arrangement disabled.

More than one case has recently come to my notice, showing how in practice the substitution of one large transformer for sev eral smaller ones has worked to the saving in first cost to the station, and, as we know from the principle of the transformer, in the economy of operation as well.

Aside from the advantages of regulation and efficiency which are far reaching in that their effect is operating continually, there are other and quite as palpable ones that especially recommend this system. Perhaps first of all comes the saving in the first cost. This plan not only preserves to you this advantage in first cost of large transformers but also admits of your using a very much lower capacity than the aggregate of the lamps wired up. There is a greater saving in the cost of installation and in the cost of repairs. Further than this the danger from lighting in the primaries is reduced at least in proportion to the number of transformers replaced.

I have spoken until now of the use of large transformers with secondaries connected on the ordinary two wire system using, if desired and the distances are not great, 52 volt lamps; otherwise 110 volts; but why stop here? The very reason why you adopted the alternating system was on account of the saving in copper in the mains and feeders, and you did this by sending a small current to a great distance at a high voltage, knowing that it is only amperage that demands a large cross section of copper. Now why not apply this principle to the secondary wiring as well, using as high a voltage as is permissable in practice. Manifestly this can be accomplished by running the secondary wiring on the 3 wire system having a difference of potential of 220 volts between the outside wires, and using 110 volt lamps. Here again we introduce a feature that, added to those above enumerated as being present in the use of large transformers, makes the system of 3wire secondary wiring from transformers the most efficient that modern practice is capable of. The loss in the secondary wiring is here cut down to minimum, as the current is only one fourth of what it would be with an equal number of lamps of 52 volts and for the same percentage of loss, the actual drop in volts can be doubled. As a consequence the wire for a 220 volt circuit would need to be but of that for a 50 volt circuit.

Ordinary transformers can of course be connected in pairs with their 100 volt secondaries in series and run out on 3-wire, but a still greater saving is secured in using a transformer whose secondaries are so brought out that a 3-wire service is obtained directly from the one transformer.

Opportunities for the employment of the step-up and stepdown transformer plan are rare in stations in this section and I have purposely confined my remarks to the employment of large transformers on the 2 wire system, or better yet two transformers with secondaries connected in 3-wire, or still better, and best of all, one large 3-wire transformer, as applications of these can be made in the plants of each one who is using alternate current.

1. Abstract of a paper read before the Northwestern Electrical Association, January 17, 1891.

tion in the amounts now paid for damages. We commend to inventors the designing of an electric car speed indicator of this class.

PATENT LITIGATION. THE SUPREME COURT ON DIVISIONAL APPLICATIONS.

WE print in other columns of this issue a late decision of the Supreme Court, which involves certain considerations as to patents issued upon divisional applications, the results of which are likely to be scarcely less important and far reaching than were those of the celebrated decision of the same tribunal a few years since relating to reissued patents. Briefly, the doctrine now laid down by the Court, as we understand it, is that only one patent can be taken for a single concrete invention, or for any part of such invention; and consequently, that when more than one patent has been issued purporting to cover different parts of the same subject-matter, all except the one bearing the lowest serial number are void. Especially is it held by the Court to be inadmissible to distribute the subject-matter of an invention between two patents, distinguishable from each other only by the different functions ascribed to a common mechanical structure.

The conclusions which have now been announced by the Supreme Court, while they will probably entail hardship upon many deserving patentees, are in our opinion, intended, by a single well-aimed blow, effectually to discourage a vicious practice which has become of late years so wide-spread and general as to constitute a notorious abuse; a remark which, by the way, may be said to apply with especial force and pertinence in connection with patents for electrical inventions. We might cite more than one instance in which a verbose and rambling specification has been filed in the Patent Office, at an early stage in the development of some particular branch of the art, containing vague references to everything under the sun which the applicant could think of as having the remotest relation to the professed subject-matter of the application. This has been kept pending in the Office for years, in order that, whenever an applicant appeared with a bona-fide invention, which appeared likely to be valuable, a divisional application could be segregated from the original mass of matter, dressed into proper shape, and put into interference with that of the new. comer. Thus a long series of divisional patents could be obtained, keeping abreast of the progressive state of the art, which, by reason of their constructively early dates, could be made to control and subordinate the work of rival, and often far more meritorious, laborers in the same field. Again, an objectionable custom has grown up among a certain class of patent-attorneys, especially some of those employed by large corporations, of filing as great a number of separate applications upon each invention placed in their hands as their practiced skill in hair-splitting could enable them to formulate; and this often, it is to be feared, with no worthier motive than the unnecessary multiplication of their own fees.

We entertain no doubt that the ultimate effect of this decision will be wholesome and salutary. As to its immediate effect there is certainly abundant room for interesting speculation. One important patent may be mentioned, which would seem to be in imminent danger of being overthrown by the new doctrine:-the famous Berliner transmit

ter patent, which, as was pointed out in THE ELECTRICAL ENGINEER of January 24, 1894, in reality covers the employment, as a transmitter, of a certain mechanical structure which, in its capacity as a receiver, was patented as long ago as November 2, 1880. There are also a very large number of patents on electric railway apparatus and devices, heretofore assumed by their owners to be control

ling, and upon which a considerable number of pending

suits have been based, which are founded upon divisional patents. Some of these, at least, must unquestionably be obnoxious to the doctrine now laid down by the Supreme Court. This authoritative exposition of the law certainly. puts a new aspect upon some important phases of the apparently interminable litigation between the rival aspirants

to supremacy in the electrical industries of the United States.

A LIE OUT OF WHOLE CLOTH.

It may be truly said that the electrical community was startled by the dispatch purporting to come from Lynn, published in the New York World, on Monday, Jan. 29, and alleging with much detail and particularity that Prof. Elihu Thomson, backed by Mr. Pevear, was about to leave the General Electric Co. and begin all over again in opposition. We characterized the dispatch as "extraordinary," yet its place of origin and its details were such as at first to make one think there might be some little truth in it, especially after the radical changes that the General Company has seen of late. Knowing that the subject is one of deep interest to many of our readers, we hastened to bring the dispatch to the notice of Prof. Thomson, whose written statement we now have to the effect that the story is wholly without foundation.

In other words, the dispatch was a lie made out of whole cloth, and probably intended to affect the stock market. It is a great pity that the liar did not confine himself to a mere flight of fancy. Prof. Thomson's distinguished services to the cause of electrical science and invention should have preserved him from any such attempts to use his great name as a catspaw for reckless and destructive speculation. It may fairly be said of him that his interest. in discoveries or inventions has been measured by their importance in increasing knowledge or in meeting some demand, and we are not aware that their prospective cash value has ever added much to the "flush of victory." The practical commercial value of an idea is of course an element of ultimate success that all great inventors must consider, if only because it furnishes the means to push forward and accomplish still more. Each discovery or invention well worked out is a conquest for mankind, and not mere "prize money" drawn from Nature. These are Prof. Thomson's sentiments, and not the low, mean ones that the dispatch so shamefully attributes to him, by insinuation.

The Fan as a Foe to Frost.

THE man who adds to the number of electrical applications is fittingly regarded as a benefactor, and in the category of such worthies should be included, we think, the genius who has utilized the electric fan for driving frost out of store windows. The experiment appears to have been tried at Lewiston, Me., with great success, and the business men are said to have put in several fans for such work, as they found they could get rid of the ice in less than ten minutes. The same cure should be effective for steamy windows. effective for steamy windows. There are many places where fans run for coolness in summer could also be employed as an aid to ventilation in winter.

LEGAL NOTES.

A DECISION LIKELY TO AFFECT MANY ELECTRICAL PATENTS.-THE DANGER OF DIVIDING

APPLICATIONS.

SUPREME COURT OF THE UNITED STATES.

No. 145.-October Term, 1893.

W. L. MILLER AND L. W. MILLER, APPELLANTS VS. THE EAGLE MANUFACTURING COMPANY.

APPEAL FROM THE CIRCUIT COURT OF THE UNITED STATES FOR THE SOUTHERN DISTRICT OF IOWA. (JANUARY 8, 1894.) MR. JUSTICE JACKSON delivered the opinion of the Court. THE appellee as assignee of letters-patent No. 222,767, dated December 16, 1879, and No. 242,497, dated June 7, 1881, issued to Edgar A. Wright, for certain new and useful improvements in wheeled cultivators, brought this suit against the appellants, who were the defendants in the court below, for the alleged infringement thereof.

The defences made in that court were that Wright was not the first and original inventor of the improvements described in the patents; that the same were shown and described in previous devices of letters-patent, set forth in the answer; that the invention shown in each of the patents in suit is identical; that in each the supposed improvements relate to a spring and its attachments; that the function and operation of the parts are exactly the same in each; that one or both of the letters-patent in controversy were issued without authority of law, and therefore, void; that in view of the state of the art at the date of the alleged improvements of Wright, the letters patent granted to him did not exhibit any patentable invention, and for that reason are invalid; that the defendants were not engaged in the manufacture of cultivators, but have sold cultivators manufactured by P. P. Mast & Co., of Springfield, Ohio, constructed under and in accordance with various letters-patent owned by that company; that they sold the cultivators of this company without notice or reason to suppose that they were an infringement of the patents of Wright, and that they do not, in fact, infringe the same.

The class of cultivators to which the Wright patents in question relate are of the ordinary character of wheeled, straddledrow cultivators, having vertical swinging beams, or drag bars, to carry the shovels or plows, suspended from an arch or frame, mounted on two wheels, a tongue fastened to the frame and beams connected with the horizontal portions of the arch, which serves as an axle for the wheels, and surrounding the axle on each side a pipe box, to which the beam is secured, the pipe box revolving on the axle, and the beam carrying the shovels adjusted so as to swing up or down with the pipe box, according to the direction in which it is turned.

The patented device consists of a round steel rod, or wire spring, having at its fixed end a coil attached to the swinging beam, or plow bars, and extending from the coil a slightly curved arm, the outer end of which terminates in a bend or shoulder, from which the rod continues to form a short arm terminating in a sharp bend, or curl, at the free end of the spring. This spring is so adjusted that the outer, or free end thereof, bears against the underside of an adjustable grooved roller, fixed upon an outwardly extending arm upon the upright portion of the axle. This spring, with its adjustment, is intended to have a duplex action, covering the double effect, of either raising or depressing the beams carrying the shovels. The curvature of the spring is such that as it moves along the groove of the roller it presses against the latter at differents points of its periphery, and thereby the direction of its action is shifted or changed, as the position of the swinging beam is changed. Such changes in the direction of its action will assist in drawing or pulling the beam upwards in a vertical direction, giving it increased leverage as the spring is moved forward in its bearings on the roller.

In his original application, filed May 23, 1879, Wright fully described his improved device for use in connection with cultivators and claimed for it, not only its lifting and depressing action, but also its lifting power, which increased as the beams were raised.

An interference with other pending applications being anticipated as to the broad claims of the invention, the application was divided, on November 12, 1879, for the purpose of obtaining one patent for the lifting and depressing effect of the spring on the beams and another for the lifting power of the spring, increasing as the beams rise, the latter being sought upon the original application, while the former was based upon the divisional application of November 12, 1879. Patent No. 222,767, for the double effect or duplex action of the improved spring, was granted on December 16, 1879, and thereafter on June 7, 1881, patent No. 242,497, for the single effect of increased lifting force in raising the plow beams, was granted, after interference had been disposed of.

The Court below sustained the validity of both patents, and

held that the defendants infringed the first, second, third, fourth and sixth claims of patent No. 222,767, and the first, second, third and fourth claims of the patents granted June 7, 1881 (No. 242,497). The complainant waiving an accounting for profits and damages, a final decree was entered, enjoining the defendants from making, using or selling to others to be used, cultivators constructed and operated in the manner, and upon the principle described in the letters-patent in controversy. From this decree the present appeal is prosecuted.

The appellants assign numerous errors, which need not separately be noticed and considered, as they are embraced in the general proposition that the court erred in holding that the patents sued on were valid, and that the cultivators sold by the defendants infringed the same. In the specification, forming part of the letters-patent 222.767, issued December 16, 1879, under the divided application filed November 12, 1879, the patentee states:

"The object of my invention is to give the operator mechanical assistance in raising and lowering the plows without interfering with their usual action and movement, to prevent the plows from rising out of the ground accidentially, and to limit their descent; and to this end the invention consists in a spring which serves the double purpose of lifting or holding down the plows at will, as may be required; in so constructing and applying a spring that it exerts a lifting action on the plow only when the latter is raised above its usual operative position; in so constructing and applying a spring that it limits the descent of the plow; also, in details of minor importance, hereinafter described.

"In carrying out my invention the one spring may be adapted to serve all or either one or more of the offices above enumerated, and may be modified in its form, construction and arrangement, as desired, provided its mode of action is retained."

[Here follow extracts from the specifications of both patents and their claims.]

It is not deemed necessary to make a separate analysis of the respective claims alleged to be infringed.

The novelty of Wright's invention consists, as held by the court below, in the application of a double acting spring to assist the operator in either lifting the plow beams, or the plows attached thereto, or in sinking them deeper in the earth, as occasion might require, while the cultivator is in service. The first patent, issued in 1879, covered both the lifting and the pressing actions or operations, while the second patent covered only the lifting effect. The spring device which was designed to accomplish these effects, or operations, is the same in both patents. The drawings in each of the patents are identical, and the specification in each is substantially the same. Under these circumstances can it be held that the second patent has any validity, or must it be treated as having been anticipated by the grant of the 1879 patent? If, upon a proper construction of the two patents-which presents a question of law to be determined by the court (Heald vs. Rice, 104 U. S., 749), and which does not seem to have been passed upon and decided by the court below-they should be considered as covering the same invention, then the later must be declared void, under the well-settled rule that two valid patents for the same invention cannot be granted either to the same or to a different party.

Thus in Suffolk Company vs. Hayden (3 Wall. 315) it was held that where two patents, showing the same invention or device, were issued to the same party, the later one was void, although the application for it was first filed, thereby deciding that it is the issue date and not the filing date which determines priority to patents issued to the same inventor on the same machine.

In James vs. Campbell (104 U. S., 382), the court say: "It is hardly necessary to remark that a patentee could not include in a subsequent patent any invention embraced or described in a prior one, granted to himself, any more than he could an invention embraced or described in a prior patent granted to a third person. Indeed, not so well; because he might get a patent for an invention before patented to a third person in this country, if he could show that he was the first and original inventor, and if he should have an interference declared. . . . If he was the author of any other invention than that which the specification describes and claims, though he might have asked to have it patented at the same time, and in the same patent, yet, if he has not done so, and afterwards desired to secure it, he is bound to make a new and distinct specification for that purpose, and make it the subject of a new and different patent." When a patentee anticipates himself, he cannot, in the nature of things, give validity to the second patent.

In Mosler Safe Company v. Mosler, (127 U. S. 355,) it was held that a patent having issued for a product, as made by a certain process, a later patent could not be granted for the process which results in the product.

In McCreary v. Pennsylvania Canal Co., (141 U. S. 467,) it was held that where a party owned two patents showing substantially the same improvement, the second was void, the court saying: "It is true that the combination of the earlier patent in this case is substantially contained in the later. If it be identical with it, or only a colorable variation from it, the second patent would be void, as a patentee cannot take two patents for the same invention."

In Underwood v. Gerber, (149 U. S. 224,) it was ruled that