ment of "giving breakfasts, dinners, tea, and suppers to passengers, either in the cabins, or under an awning upon deck."*

Had the Committee, therefore, "possessed that "accurate knowledge," in regard to the first project of Mr. Ogden, which you consider so important; had they even "seen the marks of an abortive "birth," which, you say, are " still visible upon his "boat," I doubt, Sir, they would nevertheless have persisted in believing that she had been constructed upon "principles invented by Fitch, and improv"ed by Dod." The importance of Mr. Dod'simprovements you seem to admit, but you deny their originality; and suppose me to have given up the cranks for which he obtained a patent, because every body "must have told me that cranks were the very first means applied to convert the libratory motion of "an engine beam into a rotary motion."t

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Strange as it may appear, Sir, nobody ever had the condescension to "tell" me so but yourself; for really, it is not "every body" that can pretend to that intimate acquaintance with the history of mechanical inventions, which you, doubtless, claim by the same sort of title, if not from the same source of power, to which you owe your military skill-in virtue of an honorary degree from the "Philosophical Society;" or, from having been brevetted a CIVIL ENGINEER, by your Commander in Chief. Taking it, therefore, for granted you speak knowingly, as well as authoritatively, permit me to ask, whether there was but one mode in which these vul

* Vide Appendix C. + Colden's Vind. p. 80.

gar cranks could be made to effect the purposes of their creation? Was there no room for improvement-no scope or latitude for invention? Had human ingenuity exhausted itself upon the subject, before Mr. Dod existed, or had its exercise been already claimed as one of the exclusive privileges of Mr. Fulton ?

In the first two boats which were built by Messrs. Livingston and Fulton, it will be recollected that in stead of the lever beam above the cylinder, as in Watt and Bolton's engine, there was substituted a triangle of cast iron on each side of its lower extremity. The two triangles were fixed on the same shaft, so that they worked together; and they were connected at one of the angles of their respective bases, to shackle bars or pitmen, descending on each side of the cylinder, from the cross beam in which was fitted the head of the piston rod. The angles at the respective bases of the triangular beam to which the pitmen were attached, moved therefore through a curve in a perpendicular direction, whilst their vertical angles, from which other shackle bars were connected with cranks, fixed at the sides of the propelling wheels, moved through a curve, in a horizontal direction; and in this manner a rotary motion was communicated to the wheels.

Now, instead of adopting these triangular beams and horizontal shackle bars, Dod retained the lever beam upon the top of the cylinder; attached the upper end of the piston rod to one end of the beam: and to obtain his rotary motion, he connected the other end of the beam with the head of a shackle bar or pitman, the lower extremity of which he fixed to a crank in the middle of the axis or shaft,

athwart the boat, upon which the wheels were hung, whilst a perfect rectilineal motion was given to the piston rod by means of the parallel link.* To perceive that this was a different, a simpler, and, in all respects, a better mode of converting the libratory into a rotary motion, than the cumbrous apparatus introduced for that purpose by Mr. Fulton, requires nothing but the exertion of that common sense which no brevet or diploma ever yet bestowed: for besides the evident saving in the friction, weight and expense of the machinery, the method used by Mr. Dod, induced the more material saving of room in the boat. Indeed it must have been from actual experience of the disadvantages of the old plan, that an alteration, similar in principle to that of Dod's, but by no means so simple in its contrivance, was adopted by Messrs. Livingston and Fulton, when they built the Paragon.

*It has since appeared that the same method of communicating the rotary motion to two wheels upon the sides of the boat, and connected by one axis athwart ships, had been adopted many years previous, by Mr. Morey, but it was not patented by him; nor does it appear that Dod had any knowledge of the fact. The most ingenious invention, however, for which this self-taught engineer has obtained a Patent, is an original method of driving a double set of wheels with a Steam engine, by means of parallel Lever beams, suspended upon a pivot at their respective centres, and connected at their extremities by links, which Mr. Colden seems to have confounded with the common parallel link; a pitman then descends from opposite ends of each lever beam alternately, and drives both sets of wheels together. Thus, without a cog-wheel or toothed sector of any kind; he employs one Steam engine in a boat to drive four propelling wheels, and is enabled to avail himself of a larger proportion of propellers without making his wheels so wide as to project an inconvenient distance beyond the sides of the boat. Vide infra Append. I.

As to the parallel link, it will be found that Dod's Patent was not for its invention, but for a new and beneficial appropriation of that well known piece of mechanism. And although what you state, Sir, be true," that a parallel link had been affixed by Bol"ton and Watt to different parts of their engines,

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many years before Mr. Dod could have thought of "it" you do not pretend it had ever before been applied in the same combination in which the latter had used it :—and if Dod did see it, as you suppose, "applied in many instances on board of Mr. Fulton's "boat," he could not possibly have seen it used there as "a simple and easy mode of giving a perfect "rectilineal motion to the piston rod, although it be "attached to the end of the beam which moves in a "curve," because Mr. Fulton had dispensed with the lever beam above the cylinder, so that the piston rod of his engine was not, of course, by any means attached to it.

Yet, Sir, you renew your former censures upon the Committee, for omitting to state, whether Mr. Dod had or had not seen the boats of Mr. Fulton, when they reported that the former had invented improvements upon the Steam engine," without “having seen Mr. Fulton's Patent or Specification. I informed you in my Letter, that the Committee "deemed it proper to notice that Dod had never "seen that specification, in order to guard against "the influence of his having availed himself of the "calculations contained in it concerning the requisite power of the engine in relation to the size and structure of the boat." But you still affect to consider it a singular idea; that he might have been suspected

• Colden's Vind. p. 81.

fLetter to Colden, p. 55, 56.

"of plagiarism if he had seen the patent or specifi"cation :—but that there would be no grounds for "that suspicion if he had seen the boats themselves, "of which the patent or specification is only a description."* And as if it had been possible for you to have misunderstood my meaning, you ask, with apparent seriousness, "what connection Dod's "improvement on a Steam engine-his parallel link "had with calculations of resistances ?" Cer tainly no greater connection than they had with Mr. Fulton's invention of the Steam boat, which was precisely none at all.

But you were aware, Sir, that those "calcula"tions of resistances," were not the calculations to which I had alluded; and had I even omitted to specify the particular set of calculations which had. been adverted to by the Committee, they were pointed to in the Report. It is there expressly stated, that Mr. Ogden applied to Dod to make a Steam "engine of power sufficient to drive a boat of proper size "from Elizabethtown to New-York ;-and that Dod "did thereupon, without having ever seen Mr. Ful"ton's patent or specification, make a small Steam engine as model, &c." Hence the propriety of merely noticing that Dod had not seen Mr. Fulton's Patent or Specification; and the sincerity with which you profess to "believe that the calculations were "pressed into my service merely to afford an oppor

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tunity of referring to the work of Charnock,"‡ are equally apparent.

I shall soon be led to inquire into whose "service" those calculations have been "pressed :"-but it is

* Colden's Vind. p. 82. † Vide Letter to Colden, Append. K. Colden's Vindication, p. 82.