(seq. 1)

Soho Square
{September} 1 1787

Sir

I have received your ingenious Letter relative
to the variation of the Needle, & take the liberty of advising
you to pursue with Diligence the Subject on which it ap-
pears to me you have made a progress sufficient to authorize
a reasonable hope that science will derive real increase
from your labors.

The Royal Society having lately removd
into a new House, the first Series of observations rela-
tive to the variation is only now in its Course. I cannot
therefore tell you with the utmost precision what the
variation is there; our Instrument [text illegible due to paper fold]
which probably is sufficintly exact for your purpose ~ Pre-
sently when the Instrument is moved, we shall find if the
Magnetism of the Building has any material effect upon
it of which if it has I shall with pleasure inform you.

I am Sir
your obedient
& most {Humble} Servant

{Joseph} Banks

Mr. John Churchman
Philadelphia