US$ 30.00
Lead plate with 4mm socket terminals for the simple-cell apparatus
Fine 40-60 mesh iron filings in a 100-gram sprinkle bottle
and horseshoe magnet that swap by hand
Hand-painted fracture-and-fault model demonstrating normal
and buffers for velocity
6-Piece Optical Elements Set for Hartley's Disc Subcategory_Alternative Energy Lead plate with 4mm socketAcrylic optical elements 50mm wide semicircular, biconvex, biconcave, right angle prism, and trapezoidal blocks packaged together as a spare set for the rotatable optical disc.
US$ 30.00
US$ 20.00
US$ 68.00
US$ 19.20