From Thomas Johnson
Fred[eric]k [Md.] 4 Novemr 1785.
The little Time we had at our last Meeting just allowed an Opportunity to mention several Things which were left very imperfect though we seemed much in the same Opinion; amongst them Applications to the Assembly’s to release the Company from a part of the depth of the Canals: as the four feet draft of Water, in our Circumst[ance]s, is so far from necessary that it is in some degree injurious I wish to see it in the Road of Correction and I flatter myself that an Application cannot fail—the Friends of the Company being such on the principle of public Utility, they must be inimical to a wasteful Expendit. of even private Money—the Enemies to the project being such on the principle of Economy in the public Money they must be desirous of saving as much of the 5,000£ public Money as they possibly can so that we may fairly count on all the Votes for the Correction if the new proposition will not render the navigation less useful. To lay a proper Foundation I have gone into the inclosed Calculation No. 1. I may have erred in my principles or Deductions, for I do not set up for Accuracy, and therefore wish it revised and set to rights if wrong. No. 2. is the Draft of a petition and No. 3 the Draft of a Bill; as I had only my own Ideas to guide me I make no doubt but that they may be much improved in the Matter and am confident they may in the Language the Time is too short for much Intercourse on the Subject and if they are thought sufficient for a Groundwork the only Favor I request for them or myself is that you would treat them with intire Freedom by altering as you may think best for I feel nothing of favouritism to any part my views will be intirely answered in obtaining a Release from the useless part of the Burthen.
Since my Return Home my Thoughts have run a good deal on the Situation of the Great Falls for Locks and the Manner of constructing them and their Gates. I was puzzled about the latteral pressure of Water for the Situation seems to point out Locks of great depth but unless we can come at some Rule to know the Force of a given Body of Water we do not know the Quantity of Force or degree of St[r]ength necessary to oppose to it or whether we have it in our power to oppose it with Success or not—I have no Books of my own nor am I in a favourable place to borrow Books on the Subject however I obtained one and have extracted No. 4. which I thought applicable—My Attempt No. 5. on this Foundation may probably be so far from accurate as to be intirely wrong for I have no Learning in this Way the only Merit or rather the Excuse I can claim is the Intention—Yet I cannot but be struck with the Hints started at the Falls and hope that we may accomplish a resisting Force superior to the Action of the Water let us raise it in the Locks to what height we please and I candidly confess I feel a kind of Pride in the originality or at least uncommonness of the Gates proposed—if by a Deviation from the usual Manner we can combine Strength Dispatch and Ease in a superior degree and at a less Expence than the Europeans my Ambition will be highly gratified and I flatter myself the Occasion offers.1 I should either forbear giving you this Trouble or apologize for it if I did not think your desire to pick out some thing useful from the crudest Thoughts and my unreserve will make this prolixity acceptable for I much more wish to add than to take from the few of your leisure Moments. I am Sr Your most obedt & most hble Servt
1. None of Johnson’s enclosures found at the Minnesota Historical Society appear to be numbered, but Johnson’s computation regarding the pressure of water at various depths against the sides of locks would appear to be his enclosure no. 1; his draft to the Virginia and Maryland legislatures that the depth required of canals to be built by the Potowmack Company at the falls of the river be reduced from four to two feet is his no. 2; the draft of the proposed bill (his no. 3) is missing; his excerpt from John Rowning’s Compendious System of Natural Philosophy, pt. 2 (London, 1744), 26–27, presenting a theory for measuring the pressure of water against its banks is Johnson’s no. 4; and his enclosure no. 5 is his proposal for making lock gates which would be raised and lowered by counterweight rather than having them hinged. Transcripts of the enclosures are in CD-ROM:GW. GW was not able to send copies of the petition, signed by him as president of the Potowmack Company and enclosing copies of the proposed bill, to the Virginia and Maryland legislatures until 3 December. The two legislatures promptly passed the proposed bill amending the “Act for Opening and Extending the Navigation of the Potowmack River” that both had passed at GW’s behest the year before (12 Hening description begins William Waller Hening, ed. The Statutes at Large; Being a Collection of All the Laws of Virginia, from the First Session of the Legislature, in the Year 1619. 13 vols. 1819–23. Reprint. Charlottesville, Va., 1969. description ends 68–69). See GW to Samuel Chase, 3 Dec., and notes, GW to Charles Simms and David Stuart, 3 Dec., and GW to Thomas Johnson, 20 December.