Circular slide rule and time zone scale, cardboard and plastic, made 1947 by Perrygraf, Illinois for National, Massachusetts
Details
- Category:
- Mathematics
- Object Number:
- 1985-263
- type:
- circular slide rule
- credit:
- Crosby, R.C.
Circular slide rule and time zone scale, cardboard and plastic, made 1947 by Perrygraf, Illinois for National, Massachusetts