FIG. PAGE 1. Early Lenoir Motor 24 2. Bisschop Motor 25 3. Bénier Motor 26 4. Forest Motor 27 5. Plan of Dugald-Clerk Engine 30 6. Benz Gas Engine 32 7. Otto Gas Engine 36 8. ” ” ” (vertical type) 38 9. Lenoir Gas Engine 39 10. Koerting-Boulet Motor 40 11. Niel Gas Engine 44 12. Martini Motor 45 13. Lablin Three-cylinder Motor 46 14. Crossley Gas Engine (X type) 47 15. Crossley Gas Engine 48 16. Pygmée Gas Engine 50 17. National Gas Engine 52 18-19. De Forest Gas Engines 54 20. De Forest Double Piston Motor 54 21. Diagram of Atkinson Mechanism 58 22. Section of Charon Motor 58 23. Charon Motor 59 24. Roger Vertical Gas Engine 60 25. Vertical Gas Engine of the Compagnie Parisienne du Gaz 62 26. Maurice Motor (de Cadiot) 64 27. Durand Carburetted Air Motor 72 28. De Dion Motor Tricycle 75 29. Campbell Oil Engine 81 30. Section of Grob Motor 83 31. Exterior View of Grob Oil Motor 84 32. Capitaine Gas Engine 86 33. Horizontal “Balance” Motor (Capitaine) 87 34. Capitaine Two-cylinder Gas Engine 88 35. Hornsby-Akroyd Oil Engine (section) 91 36. Exterior View of Hornsby-Akroyd Oil Engine 92 37-38. Sections of Ragot Petroleum Engine 94 39. Carburator of Ragot Oil Engine 96 40. Crossley-Holt Petroleum Engine 99 41-42. Griffin Oil Engine 101 43. Dowson Gas-producing Plant 108 44. Taylor Gas-producing Plant 114 45. Simplex Gas Engine (Delamare-Deboutteville) 123 46-47. Governor of Simplex Engine 123 48.