Saratoga & Schenectady 4-2-0 "Jervis" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class Firefly (Locobase 10313)

Data from "Early Examples of Bogie Engines," The Locomotive Magazine, Vol VIII (2 May 1903), p. 303. According to a table of ([], last accessed 9 May 2009), works number 42 was produced in 1833 as Firefly, works number 75 shipped out in 1834 as Davy Crockett.

It's remarkable how early in the development of the steam locomotive would come the cross-pollination of basic ideas from one country to the next, one continent to another. In this entry, we have a British-built pair that rode on a leading bogie. The first real bogie locomotive had appeared a year earlier as John Jervis's Experiment, to which Stephenson "undoubtedly owed something of its design ...[Jervis] is, indeed, credited with having drafted the rough outline for the builders."

The boiler is early times as well, containing as it did a bundle of tubes and a small firebox with a tall, thin steam dome on top. Ahead of the firebox stood two tall candlestick-like safety-valve columns flanking a manhole and an extremely tall stack. The latter doubtless ensured that the sparks from the wood fire would fly high and far.

(Another historical angle is the number of times early American locomotives were named for the living folk hero who by this time was a congressman from Tennessee.)

NB: Tube length is an estimate based on the calculation of tube surface area by subtracting reported firebox heating surface from reported total evaporative heating surface

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID10313
RailroadSaratoga & Schenectady
Number in Class2
Road Numbers
Number Built2
Valve Gear
Locomotive Length and Weight
Driver Wheelbase (ft / m)
Engine Wheelbase (ft / m)10.50 / 3.20
Ratio of driving wheelbase to overall engine wheelbase
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)
Engine Weight (lbs / kg)13,440 / 6096
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)54 / 1372
Boiler Pressure (psi / kPa)75 / 5.20
High Pressure Cylinders (dia x stroke) (in / mm)9" x 14" / 229x356
Tractive Effort (lbs / kg)1339 / 607.36
Factor of Adhesion (Weight on Drivers/Tractive Effort)
Heating Ability
Tubes (number - dia) (in / mm)66 - 1.75" / 44
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)6 / 1.83
Firebox Area (sq ft / m2)28.60 / 2.66
Grate Area (sq ft / m2) 5.32 / 0.49
Evaporative Heating Surface (sq ft / m2)207 / 19.24
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)207 / 19.24
Evaporative Heating Surface/Cylinder Volume200.97
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation399
Same as above plus superheater percentage399
Same as above but substitute firebox area for grate area2145
Power L12294
Power MT

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Wes Barris