... In my first experiments I was desirous of ascertaining whether a number of leeches kept separately, and placed under similar circumstances, would simultaneously give indications of thunder. I found this not to be the case: some appeared to be more sensitive and more prophetic than others; and some appeared to be absolutely stupid. And although no thunder may take place near where the leeches are, still I discovered that they take cognisance of it if it occurs at great distances. I was confirmed in my previous observations, that it is not thunder which acts upon the leech, but the electrical state of the atmosphere, which precedes thunder; and for that state of the air, all my experiments tend to prove leeches have the most remarkable sympathy. ...