21 November 1666
Cambridge

My dear Isaac,

Your paper has arrived. I haven't had time to look it over yet, but I shall find time to peruse it during the forthcoming holidays. I am, of course, very interested in what problems concerned you during the summer.

A very merry Christmas to you, my boy.

Is. Barrow


22 November 1666

FROM: Ballistics Research Dept.,
British Army Artillery

TO: Isaac Newton, A.B.,
Woolsthorpe

SUBJECT: Ballistics research data.