ScientificAmerican1875-07-31.jpg Scientific American 1875-07-24ThumbnailsScientific American 1875-08-07Scientific American 1875-07-24ThumbnailsScientific American 1875-08-07Scientific American 1875-07-24ThumbnailsScientific American 1875-08-07Scientific American 1875-07-24ThumbnailsScientific American 1875-08-07Scientific American 1875-07-24ThumbnailsScientific American 1875-08-07

Twibill's fuel economizer with an improved boiler and feed water heater.