5 1 8 Of Stone* Irregular. Part III. 
The power of the Magnet dependeth not on its Bulk 5 
(a) Muf. the fmaller, being ufually the ftronger. Tergazi {a) menti- 
TiOOf Ef- ons one3 z wou ^ f u fp en d fixty times, and Mr. Boyle, (b) 
fluv.p. 33. another, eighty times, its own weight. But the beft, in time 
loofe very much of their ftrength 3 as thefe here kept 
have done : None of them now taking up above l v \ ft 
Of what they would have done formerly, I find no Re- 
gifter. 
Some means have been propofed for preferving the 
ftrength of a Load [lone. But there is none mentioned by 
any Author, that I know of, comparable to That, experi- 
mented by Mr, Theodore Haac, Fellow of the Royal Society 5 
not only for Preferving,but alfo Recovering,and Encreafmg 
the ftrength of the Load/tone. For he having One weighing 
about liiij fT-arm'd,which would take up fixteen times its own 
weight : and having laid it bv for the (pace of fome years 
unus 'd, found it to have loft * th part of its ftrength, fo that 
it would now take up but about Jfetij. And, upon fearch, 
meeting with no means effectual to recover it 3 confidered 
with himfelf, That as in Morals, the exercife of Virtue, 
makes it more generous 3 and that Animal Motions, by ufe, 
become more vigorous : fo it might poilibly prove alfo as 
to fome Properties of Inanimate Bodies. Whereupon, he 
hung as much at his Stone, as it would bear 5 and fo left 
it for the fpace of fome Weeks. Then, returning to 
it, and applying more weight to the former, it very eafily 
held the fame. And repeating the addition of more weight, 
at feveral periods in the fpace of about two years 3 he at laft 
found, That his Stone had not only recovered its former 
ftrength, but encreas d it 3 for whereas before he had never 
known it to take up more than fixteen, it would now take 
up twenty times its own weight. And he is now continuing 
the Experiment, to fee how far it will go further. 
A GRITTY-STONE , from the Forreft of Dean 5 with 
which they there make the infides of their Iron Furnaces 3 
wherein their fire is fo vehement, that it either breaks or 
melts down any other Material. The Grains of the Stone 
muft therefore be infuperable3 yet not fo united, but 
that it is fomewhat foft and crumbly : of a dirty co- 
lour, near that of Fullers- Earth. Given by Sir John 
Hoskjns. 
ANO- 
