Tangent Galvanometer for Magnetic Field Measurement Subcategory_Botany Models Four 153 x 76mm plates

Four 153 x 76mm plates - each holding 98 iron-rod plotting compasses in a 14 x 7 matrix - assemble flat or as the faces of a cube to display 2D and 3D field-line patterns

Seventy-times enlarged skin cross section reveals epidermis

Selected through four rotary-switch decades from 0 to 11

Larger 100 x 12 x 15mm Alnico horseshoe steps the pole-gap geometry up from the 75mm model

Tangent Galvanometer for Magnetic Field Measurement Subcategory_Botany Models Four 153 x 76mm platesTangent galvanometer instrument that derives current absolutely from compass needle deflection against Earth's horizontal field, the basis for classic determinations of the local BH constant.