Henderson v. Welch Dry Kiln Co.

• Decision Date: 06 June 1928
• Docket Number: No. 18840.,18840.
• Citation: 26 F.2d 810
• Parties: HENDERSON et al. v. WELCH DRY KILN CO., Inc.
• Court: U.S. District Court — Eastern District of Louisiana

26 F.2d 810 (1928)

HENDERSON et al. v. WELCH DRY KILN CO., Inc.

No. 18840.

District Court, E. D. Louisiana.

June 6, 1928.

John D. Miller, of Miller, Miller & Fletchinger, of New Orleans, La., and Eugene A. Thompson, of Syracuse, N. Y., for complainants.

Dean S. Edmonds and Merton W. Sage (of Pennie, Davis, Marvin & Edmonds), both of New York City, and John E. Jackson, of New Orleans, La., for respondent.

BURNS, District Judge.

Plaintiffs' bill of complaint alleges infringement by defendant of their United States patent No. 1,422,202 for improvements in dry kilns designed for drying lumber. Their letters patent, dated July 11, 1922, called hereinafter the Henderson patent, comprise some 30 claims, but the plaintiffs elect to stand upon the alleged infringement of claim 4.

Defendants deny infringement, allege invalidity, and plead estoppel by conduct in bar of plaintiffs' suit. Its kilns are built under United States patent No. 1,517,928, dated December 2, 1924, hereinafter called the Welch patent.

The specifications of the Henderson patent in suit sets forth their invention as follows:

"This invention relates to dry kilns of the class used for drying lumber and other wood products, coats of paint, varnish, etc., on articles as the so-called siccative coatings, enamel on leather, etc., and has for its object construction and means for effecting and controlling the circulation of the atmosphere of the kiln and the taking in and humidifying of outer air and also the recirculating of the atmosphere in the kiln, which kiln is particularly simple in construction and especially economical to operate.

"This kiln comprises, generally, a drying room, and a heating chamber below the drying room in communication therewith, and a steam injector arranged to circulate the atmosphere in the kiln and to maintain the humidity of the atmosphere, and also to draw in, humidify, and circulate outside air and to create a draft in the stacks."

"Owing to the use of the injectors, a positive circulation is maintained in the kiln and also in the stacks, and the medium used to maintain the circulation also supplies the moisture for effecting the drying of the lumber or coatings; hence the injector performs the functions of maintaining the circulation, humidifying the atmosphere, and creating the draft in the stacks. Hence this kiln is more economical in operation than when fans and other mechanical blowers for circulating the atmosphere are employed, or when the draft is maintained in the stacks by the use of additional coils or draft-producing devices in the stacks."

Claim 4 of the patent reads:

"A dry kiln having a circulating passage having an inlet into the interior of the kiln, an air inlet communicating with the circulating passage and with the outside of the kiln, and an outlet into the kiln, and a steam blower arranged in the circulating passage between said inlets and said outlet in position to recirculate the atmosphere of the kiln and also draw in air through the air inlet and humidify the same, substantially as and for the purpose described."

I find that the claim in suit reads equally as well upon the defendant's device as it reads upon the plaintiffs'. This is because both inventions comprise the same five mechanical elements, all of which are old devices, in combination; the inventions consisting in slight improvements in structure, but with a different means or method of functioning, yet producing the same result.

The prior state of the art, upon which but slight advance was made by Henderson, appears by reference to the patents of Rubin, Emerson, and Cutler, and the documents of Brownlee.

The Rubin patent, No. 1,281,212, dated October 18, 1918, is almost identical with the Henderson patent, except for specific details in construction. Both are compartment kilns, with transverse circulation within.

The Cutler patent, No. 1,341,884, is also a compartment kiln with transverse circulation, operated in the same manner as Henderson. The principal difference is that Cutler employs fans for circulation; but both fans and steam injectors have long been recognized as equivalents in the art. (To this effect, vide British patent of Norton, No. 890 of 1863; British patent of Barff and Kidd, No. 971 of 1874; United States patent to Reyscher, No. 743,196 of 1903; British patent to Oxley, No. 28079 of 1907. The use of steam jets goes back to 1877. United States patent to Curran, No. 189,432.)

The Emerson British patent, No. 24584 of 1894, is also almost identical with Henderson. It is a compartment kiln with transverse circulation, to which Henderson seems only to have added steam jets or injectors, set in the multiple transverse ducts to draw in fresh air, humidify it, and circulate it.

The Brownlee kiln, though not patented, embodies every element of Henderson, being a compartment kiln with transverse circulation reading on every detail of claim. This prior invention and prior knowledge of Brownlee is established by his drawings and description on file in the laboratory of the Forest Products Bureau of the United States Department of Agriculture, which is open to public inspection.

In my view of the case it is unnecessary to consider the validity of the patent in suit with reference to these probable anticipations; nor is it necessary to consider the defense of estoppel, predicated on correspondence between these parties. The case of infringement may readily be disposed of on the merits, which should suffice.

In view of the prior state of the art, Henderson's patent is entitled to a very narrow range of equivalents, because it is, as stated, a combination of well-known elements, which have been used almost continuously in the art, which dates back some 50 or more years. The Henderson patent was applied for May 14, 1921, and granted July 14, 1922. The Welch patent was applied for July 19, 1922, and granted Deeember 2, 1924.

The Patent Office, in considering Welch, cited Henderson against two of Welch's claims; but the reference was withdrawn when the Patent Office concluded that Henderson's patent was for a compartment kiln, whereas the Welch patent was for a progressive kiln. The case turns upon this point for decision.

The evidence is that the Henderson dry kiln business is more or less local to New York and the adjoining states, and is and has been confined to the drying of hardwoods by the compartment kiln method; whereas the Welch Company's dry kiln business is more or less local to Louisiana and adjoining Southern states, and has been confined to the drying of pine and soft woods by the progressive kiln method.

A significant letter, written by Henderson to the Welch Company November 21, 1925, reads in part: "Although we have not entered the Southern drying field where the progressive kiln for yellow pine is in common use, we may do so in the near future. Up to date we have been mainly concerned in manufacturing compartment kilns for drying of hardwoods."

The Hendersons had otherwise recognized the difference between the compartment, or single charge, or box kiln, as the type is variously called, and the progressive kiln; that in the compartment kiln, during process, the temperature throughout the entire kiln is periodically raised, and the humidity throughout the entire kiln is periodically lowered, until at the end of the drying period the conditions throughout the kiln as to both humidity and temperature correspond, whereas in the progressive kiln, during process, the temperature and humidity is variable throughout its length. In the compartment kiln the air circulation is transverse of the kiln, whilst in the progressive kiln the air circulation is longitudinal thereof.

This requirement of maintaining variability in the progressive kiln, and uniformity in the compartment kiln, leads to distinctly different types of construction and distinctly different modes of operation or functioning. The air in any dry kiln must be kept in constant motion; otherwise stagnant areas will occur, and where this occurs it is derogatory to proper drying. In the Henderson kiln the transverse air circulation is affected by a series or plurality of transverse circulation passages, about 4 feet apart; whereas the longitudinal circulation of Welch is accomplished by two longitudinal by-pass conduits, through which the warm moist air is moved from the wet or green end to the dry end. These are but two in number, positioned parallel at opposite sides of the kiln.

Stripped of all argument predicated on the fact that claim 4 reads as well on Welch's structure as it does on Henderson's — i. e., that the Welch device corresponds with the letter of Henderson's claim — the contention is that the Henderson claim reads equally as well on Welch's commercial structure, in that Welch uses a steam blower in the recirculating passages and that his fresh air intake is the equivalent of Henderson's element 3: "An air inlet communicating with the circulating passage and with the outside of the kiln." The answer is that cold or fresh air rushes of its own accord into the Welch inlet, because it is functionally different than anything disclosed in Henderson, who must employ a steam injector or equivalent means in every one of his transverse circulating passages (four feet apart) in order to overcome frequent right angle friction, so as to distribute fresh air uniformly across the length of his kiln; whereas the injector in the Welch kiln is used primarily to speed up the...