Caleb Lownes (1754-1828), a Philadelphia Quaker, was an iron merchant who supplied Thomas Jefferson with iron for his nailery for several years. Jefferson first began his dealings with Lownes in December 1793, but ultimately found Lownes to be an unreliable supplier. Jefferson wrote to James Madison in April of 1796, "Lownes I must abandon. Above a month ago I wrote to him for an additional ton of rod, merely to  furnish a decent occasion to call for nearly that quantity still unfurnished tho paid for so long ago as October last. I find it is not furnished because it was paid for before hand. I therefore conclude to open dealings with Mr. Howel..." Lownes is perhaps more widely known as the administrator of the Walnut Street Prison in Philadelphia.
- Betts, Farm Book, 426-429.
- DePuy, LeRoy. "The Walnut Street Prison: Pennsylvania's First Penitentiary," Pennsylvania History 38(1951): 130-144.
- PTJ, 27:586-7. Identification of Caleb Lownes.
- Teeters, Negley K. "Caleb Lownes of Philadelphia, 1754-1828: Administrator of the First Penitentiary in the World - the Walnut Street Jail." Prison Journal 43, no. 2 (1963): 34-45.