There are two photos of the cannons in the PDF that Intodeep posted, and this is the description given of the two guns that are up for auction:
WATERVLIET ARSENAL Horse Drawn Cannon, 1893, 1207 pounds, # 7, W.S.P., 3 1/2” bore, 57
1/2” Wheel diameter Wood Spoke Wheels, Iron Rims - 2 13/16" wide, Hand Wheel Scissor Jack
Barrel Elevation Mechanism
WATERVLIET ARSENAL Horse Drawn Cannon, 1894, 1202 pounds, #18, S.E.B., 3 1/2” bore, 53”
diameter Wood Spoke Wheels, Iron Rims - 4 3/16" wide, Hand Wheel Scissor Jack Barrel Elevation Mechanism
The two cannons are 3.6-inch Breech loading Rifles, and can be seen on p.127 of this Google digital book. These rifles are basically just larger versions of the 3.2-inch BL Field Rifle Model of 1890, and the bigger bore gun used the same carriage as the 3.2-inch rifle. A drawing of the "lazy tongs" elevating device (described as "Hand Wheel Scissor Jack Barrel Elevation Mechanism" in the PDF) is shown on p.111, fig. 34.
3.6-inch Breech Loading Rifle