(after stating the facts as above). The substance of the claims in suit, so far as here involved is a pressure and relief attachment for use in connection with a hot water heating system, containing the following elements, viz.: (1) A mercury well; (2) a chamber in communication therewith; (3) a tube extending from said mercury well to said chamber to allow the formation of a column .of mercury in response to system pressure, and a receptacle enclosing said well, chamber, and tube — all so arranged that water may pass from and return to the system through the mercury.
The original specification seems to have contemplated this combination, but it remained for the examiner to voice it properly. It is defendants’ contention that this combination was abandoned when original claims 2, 3, and 4 were canceled in response to the rejection by the examiner. But a study of the language of those claims does not justify this construction. If they were ever intended by the applicant to cover the substance of the claims in suit, they failed of their purpose. The attempt of defendants to read into these three claims the double feature of passing and returning the fluid by reference to the then prior art does not commend itself. Certainly in dealing with the proceedings in the Patent Office the coirrt should not, by any inference', debar an applicant from the reward of his diligence in securing the benefits of his invention. Especially is this the case whenever it appears that the proceedings are not prosecuted with that discrimination and caution which a case involving this well developed art should command. It is not the spirit of the patent statutes to place the procurement of patents on technical grounds, and beyond the reach of ordinarily skillful persons. In rejecting claims 2, 3, and 4 the examiner held that there corild be no invention in substituting the Trane seal for the Grove seal. He evidently did not pass upon the question of a high pressure and a low pressure seal in one device and employing but one body of mercury. If anything were wanting to make this conclusive, we may cite his action in suggesting the claims in suit. The court will not assume that the examiner would suggest and give to an applicant a patent for a device which he knew to have been surrendered to the public. It would, in the opinion of the court, be straining both the facts and the law to hold that claims 2, 3, and 4 were identical with those in suit. Every reasonable intendment should prevail in support of the contrary proposition, and we therefore hold that the applicant did not abandon whatever of invention, if any, there is in the claims in suit, when he canceled claims 2, 3, and 4, as originally fded. As before stated, the claims in suit cover an attachment to a hot water heating system, and not a hot water heating system as such. It is evident that it must be treated as an entity, e.ntirely independent of the system. It is a device in no manner dependent upon the character of the system pressure, whereby the mercury column is lifted. That may be water, air, steam, or gas. It applies to any system in which it is desirable to facilitate the relief of *152pressure affording an avenue of escape under controlled conditions, and, when atmospheric pressure is restored, facilitate the return of water or air to the system, through the use of mercury seals, effected by the use of a single body of mercury. There is no force in defendant’s contention that it should be limited to hot water heating systems, or to a device in which the mercury is directly moved upon by water. Was there any patentable novelty in so combining the concepts of the two lines of devices of the prior art— i. e., those covering the application of a mercury seal to the protection of a hot water, hot air, gas, or steam heating system by permitting the pressure to be relieved by the escape of fluid or other substance when necessary and those which provide for a restoration of the fluids of the system to normal conditions under atmospheric pressure, when required — as to accomplish both results in one device, and with one body of mercury? The Olney patent, above cited, accomplished Something like this by the use of turn mechanical valves. There is a marked distinction to be drawn between the mercury seal and a mechanical valve: The former never fails to operate’; the latter is subject to all the defects of metalworking automatic devices. Rust and friction serve to make the latter uncertain.
The Mott and Edgar patent employs for its release of pressure, a mercury seal, and for its restoration of elements to the system, an automatic mechanical valve. Nowhere in the prior art do we find the combination of the claims in suit. That they call for a combination seems clear from the fact that they, by various skillful and novel adjustments, secure the combined effects of the herein so-called high pressure and low pressure or vacuum safety and restoration devices of the prior art by the use of only one mercury column and the elimination of a number of elements, which would be necessarily present, were the device to constitute an aggregation. The idea of a device which would pass out of the system and their at the proper time return to the system the water or air required to keep it in working order in the condition best accomplishing the end in view is both ingenious, useful, and new — not broadlj1' new, but to a degree which invades the realm of invention, the state of the art considered. The claims in suit are therefore held to be valid.
If the concept of the patent in suit is that of an independent attachment to a system for hot water or steam or hot air heating, and devised only for the purpose of protecting such system, and in and of itself a separate and distinct entity, then the fact that defendants use an air cushion between their water and mercury columns has no bearing upon the subject-matter of this suit.
Thus stripped of everything but the elements which enter into the relief device itself, it is apparent that the defendant’s construction is practically the same as that of complainant. It is true that the defendant’s mercury well 6 is comparatively small. If, however, it accomplishes the same end as complainant’s, and in the same way, the size is not material. The idea of each is identical. *153We conclude that the court erred in dismissing the bill for want of equity.
The decree of the Circuit Court is reversed, with directions to proceed further in conformity herewith.