| PAGE |
| [1]. | My First Mechanical Drawing. Longitudinal Section of my Stone-dressing Machine | 7 |
| [2]. | The First Porter Governor | 21 |
| [3]. | The Porter Marine Governor | 37 |
| [4]. | Porter-Allen Engine. Diagram of Admission—Valve Movements | 48 |
| [5]. | Vertical Adjustment of Sustaining Pin for Trunnions of the Allen Link | 52 |
| [6]. | My Improvement in Cranks and Journal Boxes | 54 |
| [7]. | My Improvement in Eccentrics | 56 |
| [8]. | Diagram from the First Allen Engine taken with the First Richards Indicator | 59 |
| [9]. | Mr. Porter’s Exhibit at the London International Exhibition, 1862 | 71 |
| [10]. | Diagram from Allen Engine in London Exhibition of 1862 | 73 |
| [11]. | Spring-testing Instrument Used in the Manufacture of the Richards Indicator | 86 |
| [12]. | Plan of Spring-testing Instrument | 89 |
| [13]. | Diagrams from English Locomotives, taken with the Richards Indicator | 91 |
| [14]. | Engine Bed Designed by Mr. Porter | 95 |
| [15]. | Cross-head Designed by Mr. Porter | 96 |
| [16]. | Connecting-rod and Strap | 99 |
| [17]. | Attaching a Steam-drum to a Lancashire Boiler | 107 |
| [18]. | Diagrams from Engine of Evan Leigh, Son & Co. | 114 |
| [19]. | Condenser and Air-pump Designed by Mr. Porter. (Cross-section) | 118 |
| [20]. | Diagrams from Engine Built for Mr. Adams | 138 |
| [21]. | Exposition Universelle, Paris, 1867. Diagrams from the “Allen” Engine Employed in Driving Machinery | 142 |
| [22]. | Pair of Diagrams from 18×30 Allen Engine at South Tyne Paper Mill, 108 Revolutions, Vacuum 28 Inches.Only Half Intended Load on Engine | 160 |
| [23]. | Cross-section of Machine Shop Proposed by Mr. Porter in 1868, after the Design of Smith & Coventry | 168 |
| [24]. | Card from Allen Engine in Colt’s Armory | 178 |
| [25]. | Sectional and Front Elevations of One of the Two Pairs of Porter-Allen Engines in the Colt Armory, Hartford,Conn. | 180 |
| [26]. | Sectional and Side Elevations of One of the Two Pairs of Porter-Allen Engines in the Colt Armory, Hartford,Conn. | 181 |
| [27]. | Porter-Allen Engines in the Colt Armory, Hartford, Conn. Front View | 181 |
| [28]. | Porter-Allen Engines in the Colt Armory, Hartford, Conn. Rear View | 181 |
| [29]. | Surface Plates Designed by Mr. Porter | 182 |
| [30]. | Diagram from Allen Engine, Back End of Cylinder, at Fair of American Institute, 1870 | 194 |
| [31]. | Friction Diagram from Allen Engine at Fair of American Institute,1870 | 196 |
| [32]. | Diagram from Allen Engine, Fair of American Institute, 1870, Cutting Off at ¹⁄₄ Stroke | 196 |
| [33]. | Apparatus for Graphically Showing the Acceleration and Retardation of the Reciprocating Parts of anEngine | 205 |
| [34]. | The Allen Boiler Facing | 208 |
| [35]. | The Prototype of the Modern High-speed Engine, Fly-wheel Side | 223 |
| [36]. | Prototype of the Modern High-speed Engine, Crank Side | 224 |
| [37]. | Longitudinal Section of Cylinder and Valves | 225 |
| [38]. | Cross-section of Cylinder and Valves | 226 |
| [39]. | Connections of Admission Valves | 226 |
| [40]. | First Arrangement of Exhaust Valves | 228 |
| [41]. | Main Bearing | 230 |
| [42]. | Eccentric and Cross-head and Crank-pin Lubricators | 230 |
| [43]. | Surface Plate for Producing a True Plane | 234 |
| [44]. | Mr. Porter’s Regulating Valve | 244 |
| [45]. | The Corliss Engine Exhibited at the Centennial Exhibition | 249 |
| [46]. | Porter-Allen Engine Equal in Power to the Exhibited Corliss Engine | 250 |
| [47]. | Mr. Porter’s Fly-wheel | 269 |
| [48]. | Connection of Arms and Rim in Mr. Fritz’ Fly-wheel | 273 |
| [49]. | Mr. Allen’s Patent Pressure Plate | 293 |
| [50]. | Diagrams from the Otis Engine | 311 |
| [51]. | Otis Engine. Dash Pot for Governor | 313 |
| [52]. | Diagrams from my First and Only Compound Engine | 318 |