Scientific American, Vol. 21, No. 10 (1869)
Scientific American volume 21, number 10 from 1869 is a weekly American science and engineering periodical aimed at general readers, mechanics and inventors. These engraved cutaway diagrams of boiler safety fittings, with numbered parts and lettered keys, show the internal valves, springs and float mechanisms of steam alarms and water gauges, useful for a designer seeking precise mechanical line drawings with reference labels.
