Robert E. Lee to Charles Carter Lee

Your letter of the 26 July has been fow - d to me at this place where I arrived two days ago - The object of my visit you will have learned from my letter to Bernard written on the eve of my departure & which I directed as he requested to Wardinsville - I am very glad that your presence has retrieved as far as may be, matters at the furnace & that your operations have been so successful & satisfactory - I hope that the streams will not fail you in your need & that you had your share of the rains that I experienced in crossing the Mountains - As regards your water power, you know that in an overshot, the water acts by its weight & the force of its impact - The first depending upon the quantity & the second the velocity - You therefore gained by the addition of your spring branch, the additional weight of water (which I cannot estimate as you did not give the velocity with which it issued through the 2 Inch hole) & its force resulting from a fall of 10 feet, the whole acting with a leverage of ½ the diameter of the Wheel. The effect of which must be considerable - By raising the furnace trunk as you propose 18 Inches, the weight of water will of course remain the same, & the additional power will be equal to the difference between the present impact & that derived from the increased height - But this difference will be small, as the velocity upon which it depends (the weight of water rem - s the same) will be but little increased. Since the fall, or the head of the stream, is the same, & the increased velocity merely arises from the different modes of conducting it on the wheel - If however you mean by elevating your trunks 18 Inches, you can get that additional height between the point of impact on the wheel & the pent stock gate (using the Millers phrase) where the water issues from the race, of course you have the increased velocity resulting from this additional fall. But if this height is gained by a different arrangement of your trunks between the said points, then the difference of velocity will be as first stated small and merely increased by a diminuition of friction - The power in numbers I can't state as I have not the data for calculating it, This is the principle & you must apply it. I hope my meaning will be intelligible - Modern experience has proved that the best application of the force of water to turn wheels is by the weight alone. The water is let on the wheel at the same height as the source so that its velocity is nothing - None of the water is wasted by sticking on the buckets, the motion of the wheel is more uniform & its diameter is the Greatest possible - The pitch-back wheel is also preferred to the overshot or any other when the quantity of water - is Small - This kind of wheel you may know turns in an opposite direction from the overshot, the water acts by its weight alone, is brought on the wheel just at the point where the weight begins to take effect, the gudgeons are consequently relieved from useless weight, the friction is diminished & the leverage increased as the diameter of the wheel is greater than the fall of the water - By fair & actual experiments in Europe this wheel has been proved to be much superior in power to the overshot & if you ever rebuild your water wheel I advise you to adopt it - The power of a stream is found by multiplying the number of cubic feet of water expended per second by the Fall - For Ex - The power of a stream furnishing 5 cubic feet of water per second, with 40 feet fall will be 5 x 40 = 200 - Of course then as you increase the fall you increase the power - You can now make the comparison you wish & understand all I have written -

I am all alive to the situation of our poor Sister in Paris - The day before leaving home I went on to see Anne - Found her suffering under the hands of the Surgeons & her mind suffering from every thing - Her pecuniary resources from the Banks entirely cut off & no remedy - After retaining barely money enough to bring me here I left with her the balance I had. I could not raise enough for Marys expenses during the Summer But had to eke her funds out by a check on the VA bank in the Event of a dividend being declared. A poor dependence I fear - This explanation is necessary to shew you the scantiness of my means - They having been already taxed in addition to our expenses over $700 - during the year & my resources being diminished - The only help I can offer is this. Mr Lloyd owes me $180. due last March. He has been expecting to pay me all the spring & I relied on that for Mary's use - He however was disappointed in collecting the money. If he can pay it to you, you can send it to Mrs Lee - It is all I can do & I will cheerfully contribute it to her support - But this if any, will be only a temporary relief - It is impossible for us to support her in Paris & she ought to return to this Country - Smith has returned & perhaps through him you can get this money from Mr. L—— I will enclose an order - I am convinced the life of Bonaparte has been sold out of the Custom House - Mr Marshall found 2 copies in Baltimore & the man said he bought them at Auction in N. York at 80 cts. Per copy - I have one - It is one of the best histories as far as it goes in the English language - Decidedly the best of that percieved that I have seen.

What a pity he could not have finished it - You will see that the rest of the matters mentioned in your letter I cannot attend to - I do not now know when I shall return - I have written in much haste & I fear confusion.

Very truly & aff - r

R E Lee