Stelles Hotel June 28th. 1805
I hoped yesterday morning to have personally answered the notes I had the pleasure to receive from you. But you were engaged when I did myself the favor to call, & I could not again wait upon you.—
The Method used, I believe most generally on the Wharves in London to raise Weights into & out of Vessels is by a Walking wheel as it is called. This Wheel brings your idea of the Wallower or Lanthern Wheel into use, but with this difference that the Man or horse walks within the Wheel, in the former & on it circumference in the latter. In [GRAPHIC IN MANUSCRIPT] both cases his weight acts with a leverage equal to the cosine of the angle formed by a line drawn from the point of pressure on the circumference & the horizon. The wheels are used in the fortifications all over Europe & are worked by the prisoners. They are variously modified, & a thousand Schemes have been tried to avoid their greatest defect the danger arising from an accidental disengagement of the Load,—by which circumstances many dreadful casualties have occurred. In large public works, these wheels, being only temporarily employed, & with less experience of danger, have been the cause of the loss of so many lives, that the hoisting machine, I have brought into use arose out of my extreme unwillingness to employ them, though otherwise undoubtedly the best means of employing the power of weight. I confess I am so pleased with your rope ladder that I shall give it a very fair trial, & have taken care to have one made, at the Navy Yard—
A few days ago (Monday) I received a most pressing letter from the president of our company to hasten my return, as our Clerk is again ill & has given notice of his resignation. Yesterday & today I have received two others, which have induced me to depend on your indulgence & to go immediately to the Northward for a short time, having first made all the arrangements for pushing the works with vigor. I shall return as soon as I can put my affairs in order at the Canal, where I must have another deputy.—
Your invitation for Monday next, Mrs. Latrobe as well as myself regret exceedingly that we cannot therefore have the honor of accepting.
I beg You to accept the assurances of the most grateful attachment & respect with which I am
Your faithful hble Servt
B Henry Latrobe.
DLC: Papers of Thomas Jefferson.