I am
NO battery-ologist, but to be fair, there have been some significant advances from lead acid to alkaline to lithium. We are also pulling astronomically more current from batteries today than is being asked of this seminal antique here. Even in our micro-devices.
However, in anybody's book, any battery that still functions at all after 176 years is darn near miraculous. If I had to guess, the technology in the Oxford Bell, while pushing a lot voltage, but very little current, would have to be the size of a car (just a random illustration) to match the amperage of an 18650.
Remember that voltage is just the electrical pressure. if there's no current (amperage) to push, the best you can hope for is for it to... well... ring a tiny bell.