### Instructions

See photocopy of instructions regarding use, and book of complementary 'numerical structure factor tables' filed under Inv. 46492 in the Object History Files.

A brief explanation from Professor Prout (Dept. of Crystallography) explained that each box was either a cosine or sine function (hence 'C' or 'S' on the lid). Each channel in the case contains paper strips used for calculating the value of part of a crystallographic equation, numbered across the instrument from 1 to 30 (sine) and 0 to 30 (cosine). (Note that the cosine boxes have one more channel than the sines; each has two spares.)

The strips in each channel are amplitude values, from 900, through 0, to -900 (at unit intervals from 100 to -100, and at hundred intervals above and below).

The strips all give values over a 90 degree range, at 6 degree intervals. Each strip has an even and an odd face: an 'E' indicates even values (0, 6, 12, 18 to 90) and an 'O' indicates odd values (3, 9, 15 to 87).

The end of each face has a number in brackets - the sum of the values on that face.

Note that the older example 80368 is simpler and covers a less extended range of values. There are strips for 1 to 20 rather than 1 to 30. The strips within each channel cover the range 99 to -99 and do not include the hundreds values. Finally, there are no odd values: each strip only has the even values - on one side positive and on the other negative.