73 Dr. Barnes on' the Affinity. 
almoft Said, in every place, Tome peculiar, and 
local improvement, which has never yet been 
extended, beyond the vicinity, where it was firft 
invented ? Of late, indeed, the fpirit of enter- 
prize has gone forth, and the inventions, made 
in one manufa&ure, have been fometimes trans¬ 
ferred to others. The machines for Spinning 
cotton, have been applied to woollen, and with 
great advantage. And, probably, both have 
been under great obligations to thofe curious 
machines, for twilling and manufacturing filk, 
which have fo long excited general curiofity, 
and admiration. 
So great is the analogy between the Several arts, 
that no man knows, to what extent the improve¬ 
ment of any Single art may affedl others, even 
where the relation, at firft fight, appears mod 
diftant. Who would have imagined, that the 
difcovery of the properties of the magnetic needle, 
would have had Such, amazing, and almoft infinite 
effects ? That, by this property alone, navigation 
fhould become fo aftonifhingly extended, new 
continents be discovered, and a new /era opened, 
in the hiftory of the globe! I was, a few days 
ago, greatly pleafed with tracing the progrefs of 
an invention, into Several branches of art, with 
which, at firft, it appeared, not to have the nioft 
remote affinity. I refer to the Cylinder, covered 
with wire-cloth, of different finenefs, originally 
intended only for Sifting flour, meal, and bran, 
immediately 
