OK, kiddies, quit arguing. The transfer bar system was invented by Andrew Fyrberg and assigned to Iver Johnson - patent 566393, granted Aug. 25, 1896.
The disadvantage of the transfer bar system compared with the hammer block is that the transfer bar is struck by the hammer every time the revolver is fired. The hammer block, on the other hand, is never touched by the hammer unless the hammer is driven forward with great force, overriding the rebound mechanism. The result is that on rare occasions the transfer bar breaks, rendering the gun inoperable.