Not sure it is that clear from the photo but the Slazenger on the right has considerable work with a raised throat area all contoured etc and similar on the shaft. So there was considerable effort going into the premium racquets.
Other things we being tried in Australia in the also. Slazenger produced a STREAMLINE which was a tear drop shape all along the shaft and around the head. If you can picture that it means thinner one side than the other. They also brought out a series called FLOATING POWER which involved a mercury filled tube inserted into the shaft. This was also done in the 1890's the theory being that during the shot added weight would give you more power. A small company EMPIRE launched a wind up balance adjustment system from a key wind in the butt cap. The mechanism inside moved a weight up or down to suit.