It's been a while since I've delved into the reference box, but finally here we have #30, a Practical Householder freebie from the 50's (I think) - Cost & Quantity Guide for Paints and Wallpapers
Not only is the cover great, but inside it has 2 movable paper charts/calculators. This lovely dial is to help calculate the number of wallpaper rolls, border rolls and ceiling rolls for the given room size...
... and this sliding chart helps estimate the cost and required amount of paint for the average room. The sliding card is printed on both sides giving ceiling and indoor woodwork guides on one side and wall, external wood and ironwork guides on the other.
The back page gives preparation instructions along with hints and tips for perfect decorating...
So there we have it, #30 - Practical Householder Cost & Quantity guide for Paints and WallpapersHave a look at previous Reference box exhibits here!