BottesiniFan

Recently I noticed a peculiar bridge design on two 3 string basses which were in their historical state, one of these basses being an Antonio Gagliano (unsure if the first Antonio or the second of the family) and Dragonetti's Da Salo. I think the Gagliano with that bridge and setup sounded very different then any other Gagliano basses I've heard or played on. I also noticed how this design wasn't present on Bottesini's Testore but as the instrument wasn't a 3 string to start he would've gotten a new bridge on it and this design may of disappeared by then. The basses I've seen it on have also been the only 3 strings still in their historical state that I know of .Does anyone know anything about this? The Antonio Gagliano (used by Rinat Ibragimov for his Bottesini 2nd concerto recording) Dragonetti's Da Salo