( ) 
i^. When you have the due length for making a 
fixt Pole, you will find the making one a fixt North , 
will confequently render the other a fixt South Pole ; 
but if keeping the fame Diameter of this Rod, you in- 
creafe its length enough, the making one end a fixt 
North Pole, will not necefTarily make the other a fixt 
South Pole, but leave it a Mutable Pole. So if you by 
a like Primary Operation make the fecond end a fixt 
Pole, the firft end will lofe its fixity, and become mu- 
table. I (ay, there's a certam kngth fuited to every 
thicknefs of Iron, to leave one end mutable, while the 
other is fixt, and the thicker the Iron is, the greater is 
this length. 
14. if you further increafc the length of the fa™ 
Rod, you will attain fuch length, that the oftner you 
have fixed a Pole on one end, and then go to fix the 
other end, the fixity of the firft will not be deftroyed, 
and that end become mutable as before, but the fixity 
of the firft end will remain, and fo you make both ends 
two fixt North Poles, or two fixt South Poles. I fay, 
the fhorteft length (for there's no tenninus of the greateft 
fcngth) for this is more in thick than in thin Iron. 
ly. The aforefaid lengths are lefs, according to the 
ftrength of Magnetifm, fi. Ignition requires a greater 
length than when a Rod is adjusted by a Loadftone,- and 
a Rod touched with a ftrong Loadftone requires lefs 
length than one toucht with a weak one. 
I have fome Years fince read Kircher, Gilhert, and 
Dr. Power ^ who mention nothing of this, nor any other 
Author as far as I remember ; I am fure it was new to 
me. 1 hear I>. Plot has a Manufcript of Mwfieur Cha-^ 
mar s Magnetieal Experiments ; alfo there's a French Au- 
thor publiiht not many Years fince on this Subject ; AJfo 
DrWa/lis thinks the Royal Society has made Experiments 
of Magnettfm. I have feen acither of thefe, perhaps they 
have done this Subjeft to much better purpofe than your 
&c. W.Ah 
