ther vermes by the feveral kinds of Barks The tannen 
know 5 that the Bark of fome Trees hath much more Salt than 
the TiiTiber ; And generally where the Barks have the ftron- 
ger or finer relifh or Vertue, the Wood hath very httle. The 
wood of the Cinamond-ir^t islnfipid-. And the wood of (7»4- 
iacum hath not halfe that vertue which the Bark hath. But in 
thefe trials we fliould take heed of a danger from the comprcf- 
fed fleams. A nd if we would ufe a deep and dry Well , for flrong 
heateby Marcafites, or otherwife, we ftiould remember Mr 
J5^i;//s proofs of the Incredible weight of the Air, and provide 
very ftrong Arches and thick Planks for the Coverture^before 
we adventure toftop in the Air ^ when it is highly rarifyed 
byfuch heates. 
' 8. But that which chiefly encouraged metogiveyou thefe 
remark es of the operations of Fro (is and Cold, is this.It growes 
in faftiipn to make C o^fervatories for Srww and Icc'^ and Mr 
JBoyle hath layd fuch deep Foundations to find out the Nature , 
property es 5 andeffedsof ColJand Frofts,that we mayalraoft 
hope , that by this branch of Philofophy , when it (hall be as 
carefully Cultivated , as Chy miftiy now is^we may perform as 
much ^ if not more and ftraoger things than are yet done by 
Fire, I dooften ask Gardeners^and skilful Husbandmen^whe- 
ther all forts of Lai^d are more fertilized jOr more fpeedily,by the 
folarlnfluenGe in our Climate 5 or by Frofts. For thefe two 
aretlie two bufy hands ^ which manure all kinds of Earth and 
Wsiiev into grateful pregnancy ,as Firgiloi Old, 
llla [eges demiim'vetis reffondet avari 
^gricoU r bis qudt felem ^ bis frigora fenftt, i GCorg^v, 47. 
And they generally affirmjthac Froft and Snow make the quick- 
er difpatchamongft us , and the more general and richer Ferti- 
lity, And,that fome Diftillations may be made by FroftsJ have 
this proof : At my requefl: you were pleafs'd to get mea Ther- 
mometer of a very fmal and flender Stem^efpecially the higher 
parts for 10 Inchesnear the head: AH that fee it, do wonder 
hew fuch a flender -Glafs could be fafely conveighed hither: 
The Spirit of wine is very deeply tinged , which renders it in 
..that fmalnefs clearly vifible : I expofedit out of Doors in the 
hardeft Frafts of the extr^ame winter Anno 1663, when the 
r ' , ' winds 
