John Herschel found NGC 3684 = h893 on 17 Mar 1831 and logged "cB; L; E; vgbM; 100" diameter." JH made a total of three observations and d'Arrest measured the position on 5 nights. JH is credited with the discovery in the GC and NGC.

But Wolfgang Steinicke found that WH probably discovered this galaxy on 17 Apr 1784 (sweep 198). After discovering NGC 3681, he turned north and found another new object, II-160, which he described as "cL, R, brightest in the middle but the brightness goes off very gradually." His position is poor -- 35 sec of RA west and 10' north of NGC 3684 and also 68 sec of RA west and 2' south of NGC 3686. Both JH and Dreyer assumed II-160 applied to NGC 3686 but Wolfgang states that WH didn't move his telescope that far north in the sweep and discovered NGC 3684 instead.

300/350mm - 13.1" (1/18/85): moderately bright, slightly elongated NW-SE, broad concentration. Second of three on a line with NGC 3681 14' SW and NGC 3686 14' NE. Also, NGC 3691 lies 15' SE.

600/800mm - 24" (5/27/17): bright, fairly large, elongated 4:3 NW-SE, irregular halo increases in size with averted, ~1.6'x 1.2'. Contains a relatively large brighter core that is nearly round and is very weakly concentrated to the center. Middle of three bright galaxies that are nearly collinear with NGC 3681 14' SW and NGC 3686 14' NE. NGC 3691 lies 15' ESE. These galaxies are part of the LGG 237 group.

Notes by Steve Gottlieb