| Patents Granted on 1820-04-?? |
Patents 1 -
11
of 11
      |
| Number | Date | Patentee | Title | Type |
| 3,189X | Apr. 04, 1820 | H. Day, J. Day | Improvement in locks | household tools |
| 3,190X | Apr. 04, 1820 | O. Parson | Improvement in boiling salt | |
| 3,191X | Apr. 04, 1820 | W. Holmes | Twisted screw auger for boring guns | gunsmith |
| 3,192X | Apr. 04, 1820 | G. Bruce | Making shaded letters | |
| 3,193X | Apr. 04, 1820 | S.D. Fuller, J. Byram | Machine for napping cloth, etc. | |
| 3,194X | Apr. 06, 1820 | P.H. Merrill | Common hoe | hoes |
| 3,195X | Apr. 06, 1820 | S. Gillet (Gillett, Amr. Of S.) | Double forcing pump | pumps |
| 3,196X | Apr. 12, 1820 | T. Newall (Newell) | Planetarium, or heliogeastrium | |
| 3,197X | Apr. 20, 1820 | R. Wilcox | Application of steam in distilling and working steam engines | distilling apparatus |
| 3,198X | Apr. 20, 1820 | R. Wilcox | Portable rotary oven | |
| 3,199X | Apr. 21, 1820 | H. Hackley | Brewing by steam | |
