Boston & Worcester 4-4-0 "American" Locomotives of the USA


Class Details by Steve Llanso of Sweat House Media

Class Nathan Hale (Locobase 13547)

Data from table entitled "Table of Dimensions of the Locomotives" in New England Association of Railway Superintendents, Report of the Trials of Locomotive Engines Made Upon 1st and 2nd October, 1851 (Boston: B J Yerrinton, Printers, 1852), p. 16.

At the same time that the B & W was taking delivery of this passenger engine, Wilmarth's Union Works in South Boston was securing orders for several locomotives from the Hudson River Railroad. The Nathan Hale (named for a railroader, not the spy) had a pressure setting of 110 psi, but the official trials BP was 99 psi.

Angus Sinclair described Wilmarth as "...an excellent mechanic and enterprising engineer, [who] had his career as locomotive builder ended through a contract he took to build a large number of locomotives [25, #167-187] each weighing 37 tons] for the Erie at a ruinously low price."

See William P Hunt, "Letters -- Seth Wilmarth and His Locomotives", Railroad Gazette, Volume XLIII, No 14 (4 October 1907), p. 383, in which he gives a full description of the consequences of Wilmarth's attempt to build locomotives for the Erie:

"Boston. Mass., Oct. 1, 1907.

"In reading the article by Mr. Caruthers in your issue of Sept. 27, 'Seth Wilmarth Locomotives,' it occurs to me that I may supply some features of Mr. Wilmarth's career that Mr. Caruthers was not able to find. At the time these engines were built I was a clerk in the office of the South Boston Iron Company, whose plant was adjoining to that of Mr. Wilmarth, and I was well acquainted with Mr. Wilmarth. His business originally was a general machine shop, until he took up the building of locomotives, and up to this time his business was successful and prosperous; but after a few years he made a contract with the Erie Railroad which brought him to bankruptcy, and his plant and business were sold out. I do not remember about his career after his bankruptcy, but have an impression that he was appointed to some superintendence at the Boston Navy Yard. I understand Mr. Wilmarth made a contract with the Erie Railroad for some 25 or 30 locomotives, which was a very large undertaking at that time, especially for a man of Mr. Wilmarth's limited means, and who was (as was generally the case with industrial manufacturers at that time) obliged to buy bis supplies on credit. When he had fairly launched in the manufacture of these locomotives he found that the Erie Railroad could not pay cash, and he was obliged to take notes in payment, and when these notes became due he was obliged to renew them. This situation destroyed Mr. Wilmarth's credit, and he was obliged to realize on his notes as best he could. I understand that for a while he sold these notes to Daniel Drew, who was a banker as well as trustee of the Erie Railroad, at a discount, but this management was short-lived, and he was forced into bankruptcy. ...

"[signed] Wm. p. Hunt,

President, Hunt-Splller Manf'g. Corporation."

NB: Boiler pressure is an estimate.


Class Rocket (Locobase 5573)

Data from a May 1, 1858 table prepared by CG Hammond, General Superintendent of the CB&Q shown in Corbin & Kerka (1960), pp 254-255.

The boiler pressure is estimated. The grate area, firebox heating surface, and total heating surface are calculated. See Locobase 5552 for full explanation. While the dimensions are not derived from actual measurement, they agree with those of similar American locomotives of the era.

Corbin & Kerka also fill in the history of this, the first Chicago & Aurora locomotive. Originally delivered to the B & W along with a sister, Neptune (works #94 & 96) in March and April 1847, the Rocket traveled to the Michigan Central, who sold it to the Chicago & Aurora in July 1852. By then it was quite a small locomotive. Even so, it made Hammonds' inventory, only to be retired in April 1859.

Specifications by Steve Llanso of Sweat House Media
ClassNathan HaleRocket
Locobase ID13547 5573
RailroadBoston & WorcesterBoston & Worcester
CountryUSAUSA
Whyte4-4-04-4-0
Number in Class12
Road Numbers
GaugeStdStd
Number Built12
BuilderSeth WilmarthHinkley
Year18511847
Valve GearV-hook
Locomotive Length and Weight
Driver Wheelbase
Engine Wheelbase
Ratio of driving wheelbase to overall engine wheebase
Overall Wheelbase (engine & tender)
Axle Loading (Maximum Weight per Axle)
Weight on Drivers
Engine Weight47095 lbs38000 lbs
Tender Light Weight
Total Engine and Tender Weight
Tender Water Capacity
Tender Fuel Capacity (oil/coal)
Minimum weight of rail (calculated)00
Geometry Relating to Tractive Effort
Driver Diameter66"60"
Boiler Pressure110 psi87 psi
Cylinders (dia x stroke)16" x 20"15" x 18"
Tractive Effort7253 lbs4992 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort)
Heating Ability
Firebox Area58.20 sq. ft34.94 sq. ft
Grate Area10.67 sq. ft 8.74 sq. ft
Evaporative Heating Surface695 sq. ft600 sq. ft
Superheating Surface
Combined Heating Surface695 sq. ft600 sq. ft
Evaporative Heating Surface/Cylinder Volume149.33162.97
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1174760
Same as above plus superheater percentage1174760
Same as above but substitute firebox area for grate area64023040
Power L125631831
Power MT


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