Clayton Cramer, on his blog, has been showing pictures of a replica Gardner Gun. The weapon is interesting, both historically and mechanically. For me, the mechanics of the weapon are of interest since the weapon had two barrels and yet the barrels didn't revolve like on a Gatling gun. The two Barrel, shown on Clayton's page works like this animation. There was also a gardner gun mechanism which just did volley fire.
James N. Gibson
Published Author, Degreed Engineer and amateur Military Historian.