[ 3$ • J 
As to the Time, when the Plates were made, the 
Inscription upon the firft fixes it to the Reign of 
‘ Diocletian ; and as not only the Characters of the 
other Infcription exactly torrefpond with that, but 
alfo the Manner of the Work upon each Plate is the 
fame 5 it is highly probable, they were all made 
about the fame time, which was near the End of the 
third Century, And to this likewife the Form of 
the Letters, particularly A and M, very well agrees. 
Nor ought it to feern ftrange, if more of them have 
not been prcferved ; Since from the Nature of them 
they appear fo liable to be deftroyed, either by the 
Injuries of Time, or for the fake of the Silver. 
Crejham College , April 2, 
1745- John Ward. 
III. A Letter from Gowin Knight, M. B. 
to the Prefident ; concerning the Poles of 
Magnets being varioufy placed . 
Honoured Sir , London, April 3. 1740 
Read April 4.*“ ■ * H E favourable Reception which 
* 745 ’ thofe magnetical Experiments met 
with, which you lately did me the Honour to commu- 
nicate to your Learned Society ^fee Tr. N° 474 * p.161.) 
incourages me to hope, that the following FaCts are 
remarkable enough to merit their Attention. 
1. I cut a Piece of natural Loadftone into the 
Shape of a Parallelopiped, i Inch t§ in Length, in 
Breadth 
