( 
46 Tlhe Si ze of Objects 
in the 45 th Page of his Phyfico-Mathematical 
Differ tat ions; the Manner whereof is thus : 
Wind a Piece of the fined: Silver Wire you 
can get a great many Times about a Pin, or 
feme other fuch (lender Body, fo clofelv as 
to leave no Interval between the Wire- 
Threads ; to be certain of which, they mud: 
be carefully examined with a Glafs. Then, 
with the Points of a fmall Pair of Compafies, 
meafure exactly what Length of Pin the 
Wire covers: and applying the Compafies 
with that Meafure to a diagonal Scale of 
Inches, you will find how much it is; after 
which, by counting the Number of Wire- 
Rounds contained in that Length, you will 
eafily difeover the real Thicknefs of the fin- 
gle Wire. This being known, cut it into 
very fmall Pieces, and when you examine an 
Gbjed:, if it be opake, drew fome of thefe 
Wires upon it ^ if tranfparent, under it; and 
with your Eye compare the Parts of the 
Object with the Thicknefs of fuch Bits of 
Wire as lie faired to your View. 
By this Method Dr. Jurin obferved, that 
four Globules of human Blood would gene¬ 
rally cover the Breadth of a Wire, which he 
had found to be T f T th Part of an Inch ; and 
confequently, that the Diameter of a fingle 
Globule was T Vroth Part of an Inch. Which, 
was alfo confirmed by Mr. Leeuwen- 
hoe k’s Obfervations upon human Blood, 
made with a Piece of the fame Wire, fent 
to 
