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Manufacturers Index - Boston Conductory Co.
Last Modified: Mar 3 2018 8:20PM by Jeff_Joslin
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This company was owned by Henry D. Stover of Stover Machine Co., who had an 1860 planing-machine patent. Around 1876, Stover formed this company to "license" his patent to owners of machines that allegedly infringed on his patent.

The key patent claim is for the use of the air current created by the spinning planer-head to convey chips into a chip-collection hood (the "conductory"). Yet the Nicholas G. Norcross patent of 1850 used substantially the same arrangement as the Stover patent, without claiming protection for the idea.

Here is the complete text of an 1877 article in Manufacturer & Builder about this case:

Since the publication of the communication in regard to the Stover patents, in our May number, "Wood-Working Machinery," we have made a thorough investigation in regard to the matter and the interests involved, which we now present to our readers.

The Boston Conductory Company—or H. D. Stover—professing to be the owners of the patent granted to H. D. Stover in December, 1860, upon planing machines, have for some time past been extorting various sums of money from the users of wood-working machines, claiming royalties, etc., for an alleged infringement of their patents. Many parties, rather than be annoyed with a threatened law suit, have submitted to their extortions, and have paid sums varying from $50 to $300, in order to be let alone.

During the fall of 1876, they brought suits against several prominent parties in Chicago for various amounts, which as yet have not been tried. The parties sued have formed an organization styled the Boston Conductory Defense Association, and have tried every means in their power to have the suits instigated by the Stover and Boston Conductory Company brought to trial, but as yet without avail.

Mr. B. F. Sturtevant, of Boston, has for the past two years endeavored to bring the matter to a test, using every means in his power to induce the Boston Conductory Company and Mr. Stover to bring a test suit against any of his customers, he being ready, and has been at all times, to defend any of his customers against the claims of the above parties.

We are indebted to Mr. I. R. Joslin, Vice-President of the S. A. Woods Machine Company, for some important points in regard to the asserted claims for the use of an exhaust-fan and shaving conductor, and of some other details in woodworking machinery, while we are also indebted to Mr. C. W. Forbes, (who was employed by Mr. Joslin as an expert to examine the patent records in Washington,) for many other matters of importance embodied in the following paragraphs, which we recommend to the serious perusal of all parties interested. We may remark that Mr. Forbes has had large experience in the patent business, having been examiner in the Patent-Office for six years, and is therefore perfectly familiar with the patent law, and is undoubtedly a competent and reliable expert in these matters.

The information which we are about to give for the especial benefit of those who intend to defend themselves against Mr. Stover's pretensions, would not be complete if we omitted to give the legal opinions on which Mr. Stover bases the prosecution of all who use any of the devices in question. These opinions, as will be seen, are of such a nature as may be obtained in almost any case when partieis are interested in knowing only what is to their advantage, and intentionally ignore the other side of the question.

The first legal opinion brought forward by Mr. Stover, is that of Mr. George Gifford, who says, substantially,

"I believe the claim to be good and valid, from the fact that the subject matter of that claim, together with the subject matter of the other claims in the patent having been three times submitted to the order of the Patent-Office scrutiny, one at the time of the original grant, again at the time of the re-issue, and finally when the re-issue was extended. You have very strong assurance that nothing could be found against it, and that it is good and valid for all it purports to secure.

"The claim is to the combination of a conductory made of any suitable material, with a planing-machine cylinder, in such manner that the shavings, dirt, etc., shall be thrown into the conductory, and thereby be conducted away from the machine, their travel through the conductory being aided by the current of air produced by the revolution of the cylinder.

"I have been familiar with all the principal planing machines in use for the last thirty years, and never knew or heard of such a combination prior to the date of your original patent. I have no hesitation in saying that my opinion is that the 13th claim referred to, is in all respects good and valid, and that you can en-force it against all infringers and recover of them damages for past infringements, and obtain injunctions re-straining them from future infringements."

The next document is an opinion of Samuel A. Duncan, who says:

"The patent evidently assumes that you are the first one to utilize the air current caused hy the revolution of the cylinder, for the purpose of conveying the shavings, chips, and dust away from the works into a conduit through which they can be taken to any desired destination, and thus be prevented from encumbering the machine. Upon this theory the claim of the patent (13th clause) admits of but one interpretation - it covers every form of conductory for the removal of shavings, the mouth of which is placed in such position relatively to the planihg cylinder, that the current of air generated by the revolution of such cylinder will cause the shavings and other debris to enter such conductory.

"The specification describes the special form of the conductory shown in the drawings as being attached to the cross-head, but the claim is not thus limited, and evidently this special mode of mounting the conductory is a matter of convenience merely, and not necessity.

"Some question seems to have been made as to whether the air current caused by the revolution of the planing cylinder, is strong enough to force the shavings through the entire length of the conductory. This would depend entirely upon the length and inclination given to the conduit constituting such conductory. Of course a conduit might be made of such length and so arranged that the force of the air current would be weakened by friction against the interior walls to such an extent as to render it unable to carry the shavings entirely. through; but even such a structure, in my opinion, would embody your invention, provided the air current be sufficiently strong to carry the shavings into the conduit. The main object will have been accomplished, namely, the shavings and dust will have been removed automatically from the bed of the machine, and bymeans of the planing cylinder acting as a fan-blower to drive them into a conduit through which they can subsequently be conducted to any desired place of deposit."

In regard to the exhaust-fan and fan-blower, it is claimed that the Stover Machine Company is the owner of the patents of Ransom Cook, granted November, 1861, and the opinion of Mr. George Gifford is brought forward, who says:

"I have carefully examined copies of the aforesaid patents in connection with the pre-existing state of the art in reference to the subject matter to which they appertain, and my opinion is that Cook does cover the combination of a fan with the tube or pipe, so as to avail of the joint power of the fan suction and the blast produced by the centrifugal force of the cylinder."

Finally, the Stover Machine Company says in regard to what they call their conductory clause: "It has been examined into by a large number of planing-mill proprietors, and, after a thorough investigation, have not only procured a license for its use, but have given certificates to this effect."

Now let us look at the other side of the question. In regard to the patents of Cook, Nos. 33,693 and 33,694, dated November 12, 1861, it is found that, in view of several patents of prior date showing the combination ofan exhaust-fan and fan-blower with a conductory for the same purpose, his patents are limited in their scope to mere details of construction confined to the form and arrangement of the fan-vanes; and regarding the 13th clause of the claim of the Stover patent, the following extracts from the patent of N. G. Norcross, dated February 12, 1850, No. 7,087, for wood-planing machines, are sufficient to satisfy any one, and to prove in any court of justice the utter worthlessness of this claim, and also to show how an innocent inventor may be misled by a repeated oversight of the Patent-Office and the blind assurances of eminent counsel:

"The rotary cylinder is arranged within the upper part of a conductor in such a manner that the shavings or wood removed by it from the board, shall pass or be thrown into the said conductor. This conductor should be made so close that no shavings or chips can escape from out its sides while the machine is in operation, the object of it being to collect the shavings or chips and preserve them from accidental contact with fire. This conductor may lead down and open into a close box or chamber formed under it, or under the planing machine. The said conductor and its chain. ber, or either of them, may be made in any suitable manner, and there may be applied to either one or both of them one or more suitable openings for the purpose of removing the accumulated shavings. As the rapid revolution of the rotary cylinder causes it to operate on the air someWhat like a fan-blower, there will be a current or currents of air more or less rapid created in the shaving conductor or chamber. In order that such currents may be rendered advantageous, a pipe may be led from either the conductor or the chamber and be carried therefrom out of the building, or into such an apartment or place as circumstances may require. The currents of air which are caused to rush into the conductor, prevent the escape of any dust or shavings, and force the same downwards."

In the adjoined illustrations Fig. 1 represents Norcross's planing machine; A is the frame, B B the rest-bars, C the board to be planed, and E the rotary cutter-head revolving under the same and planing the board from below; m2 is a conductory connecting with a chamber or receptacle n2, and a2 is a pipe leading from this receptacle to give exit to the air. In the specification it is especially mentioned that the pipe a2 may be connected immediately with the conductory m2, omitting the chamber n2. It is evident that when this is done the identical arrangement claimed by Mr. Stover is obtained.

In regard to Mr. Gifford's opinion upon the Cook patents, it is evident that neither of said patents show or describe his apparatus applied in connection with the rotary cylinder of a planing machine. These patents do not cover the combination of an exhaust-fan and conductory with the cylinder of a planing machine so as to secure "the joint power of the fan suction and the blast produced by the centrifugal force of the cylinder."

If the association of Mr. Stover's patent with Cook's will produce the desired combination, a similar connection may be effected between the patent of Norcross cited and the patent of T. Fairbanks, for example, dated May 26, 1843, No. 3,105, wherein an exhaust-fan and conductory are clearly set forth, and still antedate Mr. Stover's patents.

This machine is represented in Fig. 2 in perspective, and in Fig. 3 in section. The same letters refer to the same parts; A is the grinding-wheel, a the conductory, C the chamber to receive the material ground off, E an exhaust fan, and F a continuation or extension of the conductory.

It would seem that in view of the above facts, the wood-working people, and those acquainted with patent laws, would need no further information or assistance to determine whether the claims of the Boston Conductory Company or H. D. Stover, in relation to exhaust fan-blowers and shaving-conductory, are valid or not; and it is fair to presume that any further demands of the above plaintiffs for royalties will be received with cold shoulders.

Considering all the above facts, we think that further comment is unnecessary. It has become self-evident that the principal claim of the Stover Machine Company cannot hold, being anticipated by appliances of which the time has run out.

We propose in the future to keep our readers and patrons posted from time to time on all fraudulent demands of patent claims on patents, thereby preventing any pretended or fraudulent claim from being established to the detriment of innocent parties and users of machinery.

Information Sources

  • The above article is from the June 1877 issue of Manufacturer & Builder.
  • The May 1877 issue of Manufacturer & Builder carries a long letter to the editor from an anonymous correspondent who outlines—and then rebuts—the patent claims of the Boston Conductory Co.
  • The July issue of the same journal carried more information, coming primarily from Isaac R. Joslin of S. A. Woods Machine Co.