{"product_id":"vintage-marine-engine-valve-propeller-motion-demonstrator-by-clarence-e-long","title":"Vintage Marine Engine Valve \u0026 Propeller Motion Demonstrator by Clarence E. Long","description":"\u003cp\u003ec. 1930s; Clarence E. Long Marine Engineering School - Milwaukee, Wisconsin\u003cbr\u003e\n\u003cbr\u003e\nMechanical marine engineering demonstrator constructed as an instructional display to illustrate the relationship between propeller rotation and internal valve or linkage motion. Mounted on a painted wooden backboard with integrated base and carry handle, the piece features a brass and steel linkage assembly connected to a small metal propeller. Turning the propeller drives the vertical mechanism, clearly showing coordinated movement through the sliding plates, levers, and pivots. The layout is intentionally exposed, allowing students or viewers to visually trace motion transfer in real time-an effective teaching aid for early marine engineering education.\u003cbr\u003e\n\u003cbr\u003e\nA metal maker's plate at the lower right reads \"Designed, Mfd. and Sold by Clarence E. Long, Marine Engineering School, Milwaukee, Wis.\" Clarence E. Long operated a specialized training school focused on marine and mechanical engineering, producing purpose-built instructional apparatus like this for classroom and demonstration use during the early 20th century.\u003cbr\u003e\n\u003cbr\u003e\nIn good working condition, with the mechanism moving smoothly up and down as intended when the propeller is turned. Shows light surface wear, oxidation to brass components, and minor paint wear to the board consistent with age and instructional use; overall presentation remains strong and intact.\u003cbr\u003e\n\u003cbr\u003e\n7\" W x 15\" H\u003cbr\u003e\n\u003cbr\u003e\nMM - 18329 - 121525\u003c\/p\u003e\n\n\u003cp\u003eFor information regarding shipping, please visit our Terms \u0026amp; Conditions page \u003ca class=\"GeneratedLink\" href=\"https:\/\/industrialartifacts.net\/pages\/shipping\" target=\"_blank\"\u003ehere\u003c\/a\u003e.\u003c\/p\u003e\n","brand":"Industrial Artifacts","offers":[{"title":"Default Title","offer_id":42576405069867,"sku":"18329","price":1750.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0194\/8170\/files\/80cfebb6-79d6-5a9f-9088-85507603b461.jpg?v=1765930554","url":"https:\/\/industrialartifacts.net\/products\/vintage-marine-engine-valve-propeller-motion-demonstrator-by-clarence-e-long","provider":"Industrial Artifacts","version":"1.0","type":"link"}