I return you Mr Coffee’s communication with my thankful acknowledgments for it’s use. I learn that the undertaker of the locks of the James River Canal has succeeded in making the chambers impervious to water, by laying the masonry in a mortar of Roman-Cement, without lining the walls with plaster. He supposes that with well burnt bricks, or such as have a vitreous coat, a cistern may also be made quite secure without plastering the inside. Should we fail in the experiment, we can easily add the lining, according to mr C’s method afterwards—

I observed that earthen tubes were used in the gardens about Paris & Lisbon as aqueducts under ground, & find that they can be made at our Potteries, as my cistern is not very contiguous to the pipes which communicate with the gutters, I mean to make trial of them. They are less expensive than metal & more durable than wood, & should you have occasion for any of them, I will with pleasure order some for you, provided they succeed with me.