Lawrence Slide Rule 250-BT 1940’s Vintage Lawrence Engineering Service

Vintage Lawrence Engineering Service 10-B Slide Rule, 1940s

Lawrence Slide Rule 250-BT 1940’s Vintage Lawrence Engineering Service w/Box

Vintage Lawrence Engineering Service Wooden Slide Rule w/leather case 250-BT

1940s Wood Slide Rule Leather Case No Slide Lawrence Engineering Service 250-BT

Vintage 1940s Lawrence Engineering Service 250-BT Wood Slide Rule USA with Case

Vintage Lawrence Engineering Service 250-BT Wood Slide Rule USA with Case

Vintage Slide Rule: Engineering Instruments inc 250-BT in sleeve, missing cursor