Details and Image
Area of Use
Circular and Spiral Slide Rules
Schacht & Westerich / RECHENUHR - System Thomas
Schacht & Westerich
Ø 8.4 cm
The possible maker is better known as a retailer. Consisting of four stacked brass discs with: (i) the outer and inner discs fixed and (ii) the second and third discs free to rotate. Accompanying case is possibly homemade and not original.