15. I have seldom seen the change to be very great, at any one time. For, though I do not now take a deliberate view of my Notes, yet I wonder'd once to see, that in one day it subsided about 3/4 of an inch. 16. Of late I have altered my Method upon the _Barometer_, observing it, as it is before my Eyes, all day long, and much of the night, being watchful for the moments of every particular change, to examine, what cause in the Air and Heavens may appear for such changes. And now my wonder is, to see, how slow it is, it holding most between the nine and twentieth and thirtieth inch of late. 17. I must now (_January_ 13. 1665/6) tell you, that the _Mercury_ stands at this time (as it did also yesterday) a quarter above 30. inches; yet both days very dark and cloudy, sometimes very thick and misty Air; which seldom falls out. For, for the most part, I see it higher in clearest setled weather, than in such cloudy and misty Foggs. This thick Air and darkness hath lasted above a week; lately more Cold, and _East_ and _North-East_ wind. [Sidenote: _This seems to be wished, because the motion of the _Mercury_ may be more free in a wider Cane._] _Thus far_ the Notes of this Observing _Divine_; of which Mr. _Boyle_, to whom they were also communicated, entertains these thoughts, that they seem to him very faithfully made, and do for the main, agree well enough with his observations, as far as he remembers, not having them, it seems, at that time, when he wrote this, at hand; and though it be wished by him, that the Observer's Glass-Cane had been somewhat bigger; yet his diligence in fitting it so carefully, or rather so skilfully, as is above-mentioned, is much by him commended. {160} * * * * * _Some Observations of _Vipers_._ A curious _Italian_, called _Francesco Redi_, having lately had an opportunity, by the great number of Vipers, brought to the _Grand Duke_ of _Toscany_ for the composing of _Theriac_ or _Treacle_, to examine what is vulgarly delivered and believed concerning the Poyson of those Creatures, hath, (according to the account, given of it in the French _Journal des Scavans_, printed _January_ 4. 1665/6) performed his undertaking with much exactness, and published in an Italian tract, not yet come into _England_, these Observations. 1. He hath observed, that the poyson of Vipers is neither in their _Teeth_, nor in their _Tayle_, nor in their _Gall_: but in the two _Vesicles_ or _Bladders_, which cover their teeth, and which coming to be compressed, when the Vipers bite, do emit a certain yellowish Liquor, that runs along the teeth and poysons the wound. Whereof he gives this proof, that he hath rub'd the wounds of many Animals with the _Gall_ of Vipers, and pricked them with their _Teeth_, and yet no considerable ill accident follow'd upon it, but that as often as he rubbed the wounds with the said yellow Liquor, not one of them escaped.