March 15, 1945

Dr. W. T. Astbury

Textile Physics Laboratory

The University

Leeds, 2

England

Dear Astbury:

I send you herewith a set of eleven cards representing fifty cos 12 X and another set representing minus 10 sin linex. You will note that negative numbers are represented by the remainder on subtracting them from one million. There is also inclosed a sheet of paper, at the top of which the first set is tabulated, then the second set, and then the sum of the two.

There is a chance that there is an error, possibly more, on these cards - they were punched out by hand, because at present we do not have a duplicating punch.

We might be able later on to provide you with a complete set of cards at very small cost, in case that you can use them. Our facilities at present do not permit us to make a duplicate set readily, but this situation may be changed later.

I do not have at hand a description of the application of the method of least squares with use of punched cards. I hope later on to have a copy of a manuscript on this subject, which can be sent to you. We are, indeed, hoping to publish two or three papers before another year is out, describing all of the punched card work done here.

I am looking forward to the time when I can see you again.

Sincerely yours,

Linus Pauling

LP:fh