TALBOT137

My dear Sir,

You will find the subject of Reciprocal polars very well treated of in [illegible] which I now send.

The word reciprocal is sometimes (improperly) used for a curve to a radius vector the reciprocal of another e.g.

[illustration]

if rcosè = a be the equation to a st. line ¹/_r cosè = a is the equation to a circle of which the radius is ½a.

I am Yours vy truly
Philip Kelland

H. F. Talbot Esq