t s*° 3 
dand, if at red. Being unwilling to- part with thefe 
Advantages, I contrived a light Circle of Brafs, of 
the fame Diameter with the Card, which will Tup-, 
ply a Weight acting at the greated Didance from the 
Centre of Motion, and alio ferve to fupport the 
Card 5 which may now be made of thin Paper, 
without any thing to ftiffen it. So that the extra- 
ordinary Weight of the brafs Ring is compenfated 
in a great meafure by the Lightnels of the Card. 
This Ring is of Service in another refpeCt ; for, being 
fixed below the Card, and the Needle above it, the 
Centre of Gravity is placed low enough to admit of 
the Cap being put under the Needle ; whereby the. 
Hole in the Needle becomes unnecefiaryj and the 
latter being placed above the Card, renders it ealiec 
to be touched with a Pair of Bars. 
Having thus completed the Needle and Card to 
my Satisfaction, what chiefly remains, is, to contrive 
fuch a Cap and Point as will have the lead Friction, 
and be mod likely to continue in a State ot Per- 
fection. The Caps in Ufe are either of Brafs, a mixed 
Metal, like that of a reflecting Telefcope, Cryflal, 
or Agate. The two firfl will only admit of brafs 
Points, and the latter are rather too expenfive for 
common Ufe. Wherefore 1 bethought myfelf of 
trying glafs Caps: 1 had three of them made by a 
Glafs-blower, two of which I got polifhed: They 
were all fet in Brafs, fo as to fcrew into the fame 
Needle, which had alfo one of Agate fitted to it. I 
compared them with that of Agate, by trying with 
each of them how many Vibrations the lame Card 
and Needle would make, when drawn afide 90 
Degrees, 
