{"product_id":"untitled-feb14_09-34","title":"Dobbie-McInnes Hopkinson Flashlight Indicator with Photographic Hood","description":"\u003cp\u003eA very rare and intriguing Dobbie-McInnes Hopkinson Flashlight Indicator with Photographic \/ Telescopic Hood. This particular engine indicator is particularly rare given the condition of the photographic hood which has survived well over one-hundred years. According to John Walter in his 'Engine Indicators: Autographic and other recorders from the time of James Watt to Today (Part 5: Clever Tricks)' (2024), Dobbie McInnes may have only made 250 Hopkinson Optical Indicators, so the likelihood of others surviving in a condition as complete as this one is highly unlikely. \u003c\/p\u003e\n\u003cp\u003eThe design of the Hopkinson Indicator is such that a pin-point beam of light is directed onto a mirror and reflected on a photographic plate or through a special observation telescope, where the changes of pressure during the operating cycle of an engine are traced as a permanent record.\u003c\/p\u003e\n\u003cp\u003eThis one is in remarkably good condition. Two screws are missing from the hood and there is a small chip the corner of the glass plate but it is structurally good. A fantastic, collectors' indicator which also makes for a great display item.\u003c\/p\u003e\n\u003cp\u003eAny questions feel free to ask.\u003c\/p\u003e","brand":"Dobbie-McInnes \u0026 Clyde Ltd.","offers":[{"title":"Default Title","offer_id":52476734996808,"sku":"S2233","price":175.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0912\/0147\/0792\/files\/E9BA20C7-E3AC-4E48-B246-4375F2D52D46.jpg?v=1771061730","url":"https:\/\/anthonycollectables.com\/products\/untitled-feb14_09-34","provider":"Anthony \u0026 Co Collectables","version":"1.0","type":"link"}