As you can see the felt is simply glued-on all around the hammer, including the tip. The felt itself is quite soft and not resistant to tension, unlike leather and conventional wool-felt used for piano. It is quite pliable and if I were to stretch it it would pull apart.
This is the kind of felt that Grand Pianos used By Chopin, Liszt etc. used between 1830 and 1850 on Pleyels and Erard pianos.
Being so delicate it only lasted a few years and it was discontinued after about 1850 or so, being replaced by a thicker layer of fine lambswool-felt

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