Trade Catalogs on Scientific Laboratory Equipment for Physics, Chemistry, Biology, Agriculture, and General Science ; Blast Lamps, Microscopes, Dissecting Sets, Tuning Forks, Pumps, Balances, Scales, Meters, Truss Units, Hydrogen Ion Apparatus ; Biological Charts and Specimens, Lantern and Microscopic Slides, Etc. ; Amateur Science Kits, Radio and Electrical Apparatus ; Centrifuges, Chemicals, Laboratory Furniture, Mathematical Models, Physics Apparatus and Charts, Etc. ; Classroom Supplies, Notebooks, Pencils, Erasers, Desks, Chairs, Drinking Fountains, Maps, Playground Equipment, Bells