ILLUSTRATIONS 



Plates 



1. Scope of the collections of the Division of Engineering Frontispiece 



Facing page 



2. Mechanical elements 4 



(1) Roller, lever, and inclined plane. 



(2) Chinese windlass. 



(3) Differential chain hoist. 



3. Treadmills 5 



(1) Human treadmill, c. 1588. 



(2) Dog-powered treadmill, 1878. 



4. Windmills 8 



(1) Smock windmill, e, 1826. 



(2) Post windmill, c. 1826. 



(3) Grist windmills on Long Island, c. 1874. 



6. Windmills 9 



(1) Monitor windmill, 1881. 



(2) Moses G. Farmer wind-electric generator, 1880. 



6. Water wheels 16 



(1) Vertical water mill, c. 1588. 



(2) Burden Iron Co.'s water wheel, 1851. 



7. Wooden water-mill gearing, c. 1870 17 



(1) Spur gears. 



(2) Pinwheels. 



8. Pelton water-wheel buckets, 1901-1912 22 



9. Conowingo hydroelectric generating station, 1928 23 



10. Early steam engines 28 



(1) Heron's turbine, c. 150 A. D. 



(2) Watt pumping engine, "Old Bess," 1777. 



11. Newcomen pumping engine, c. 1717 29 



12. Early steam engines in America 40 



(1) Half cylinder of the first steam engine in America, 1755. 



(2) John Stevens steamboat engine, 1804. 



13. Steam engines, 1864-1875 41 



(1) Horizontal steam engine, 1864. 



(2) Thompson and Hunt steam engine, c. 1875. 



14. Small multicylindcr steam engines 54 



(1) First Stanley steam automobile engine, 1897. 



(2) Westinghouse Junior automatic engine, c. 1900. 



15. Three-stage steam turbine, 1926-1930 55 



16. Adjustable cut-off valve gears 66 



(1) Sickels drop cut-off valve gear, 1841. 



(2) Mien adjustable cut-off valve gear, 1841. 



17. Adjustable cut-off valve gears 67 



(1) Francis B. Stevens cut-ofT, 1861. 



(2) Corliss drop cut-off valve gear, 1849. 



IV 



