be collected from the fweiting of Stones, cracking of 
Wain/cote, &c. So that indeed* I repute it to be the 
niceft/;^^r<?;;2^^^r, that has ever yet beenufed, and I am 
fiireis ascheap and plain as any. 
One of the grand defeats of nioft (indeed I think of all,) 
Hydrometers hithcvto invented is, that they grow weak 
with age, and do not fo nicely obey the alterations of the 
^ir, when long kept, as when firft made ; Planks and 
Boards grow more feafoned, and I beleive Oat-Beards 
will perilh with time ;, but whether ourprefent Inven- 
tion be fnbjed: to the fame fault, I leave to time to deter- 
mine; in the mean while, give me leave to propofe a 
reafon which induces me to conjeiture probably it will 
not have this defedj for our Cord performs its motion 
as it is a plyable foft fcrew, and that not only in its gro(i- 
fer part or ftrands, but even in its Imallell threads; as long 
as ever this contexture fcrew- wife dos laft ("and this cer- 
tainly mutt laft whilft'tis a Rope J the motion thatre- 
fults therefrom muft neceffarily latt, for the particles of 
moifture will infinuate themfelves, and twift up the 
fcrew. But this I offer only as a conjedture, for I love to 
conclude nothing in natural Philofophy , till matter of 
fad: and experiment confirm it. 
There remains one thing to be obferved of this Hygrafr 
cope [or IFeatherclocJ^r an eafier name to fatisfy La- 
dys, thatenquire whatitis, asit hangis up in a Room,) 
that which Ihave defcribed t have ia^my Glofet, and I 
obferve that the alterations of th^ ^ir that have happen- 
ed in this time have given it more then one turn,- now 
this being inconvenient, and the Duplication of the 
turn hard to be regiftred, as Mr, Hooi^ propofes in his 
Micrography pag. ij-o. concerning the beard of a wild- 
Oat j I have thoughtofa way for remedying this, for it 
being in our power to increafe the Diameter of our gra- 
duated Circle as large aswepleafe, what need have we 
of mpre then one turn from the greateft^ degree of moif- 
ture 
