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that neither the variation of the plane existing in the chain of ossicles, nor the presence of the articulations, is sufficient to prevent the progress of sonorous undulations through this chain to the vestibule.
The experiments and observations detailed above lead to the following conclusions:
1. That the commonly received opinion in favour of the sonorous undulations passing to the vestibule through the chain of ossicles is correct.
2. That the stapes, when disconnected from the incus, can still conduct sonorous undulations to the vestibule from the air.
3. So far as our present experience extends, it appears that in the human ear sound always travels to the labyrinth through two media, viz. through the air in the tympanic cavity to the cochlea, and through one or more of the ossicles to the vestibule.
In a recent communication, since ordered for publication in the Philosophical Transactions, I described some experiments on the electrical discharge in a vacuum obtained by the absorption of carbonic acid with caustic potassa, and I showed that, when the discharge from an induction coil was passed through such a vacuum, the stratifications became altered in character and appearance as the potassa was more or less heated. I have also in a former paper (Phil. Trans. 1858, p. 1) shown that the stratified discharge can be obtained from the electrical machine.
A description of an extended series of a water-battery was communicated by me as far back as December 1843 (Phil. Trans. 1844, p. 39). This battery consists of 3520 insulated cells: some years had elapsed since it was last charged, and I found the zincs were very much oxidated; on again charging it with rain-water, I ascertained that there was sufficient tension to give a constant succession of minute sparks between two copper discs attached to the terminals of the battery, and placed about ⅛th of an inch apart. On attaching the terminals of the battery to the wires in a carbonic acid
