firebox designs advocated by various inventors and 
engineers, Millholland among them.) The Scientific 
American went on to state that cast-iron plates 9 inches 
wide on each side and 16 inches wide at the rear were 
placed on the grates in an effort to protect the firebox 
sheets from the direct action of the fire, and thus only 
the center portion of the grates was open. ‘This 
arrangement may have preserved the firebox, but it 
hampered combustion by restricting the free passage 
of air to the underside of the fire. 
A second and more important modification was the 
placement of the combustion chamber near the center 
of the boiler waist. The central combustion chamber 
was connected to the firebox by a number of large 
(3- or 4-inch-diameter) tubes; the gases were carried 
to the smoke box by regular small (2-inch-diameter) 
tubes. Ideally, all of the combustible gases not 
burned in the firebox would burn in the central 
chamber before passing to the smoke box. In practice, 

however, the temperature of the gases, already too 
cold for combustion, was further reduced in the central 
chamber, where they were mixed with more cold air. 
Millholland was overly concerned, as were many other 
engineers, with the quantity of air required for good 
combustion. 
On February 17, 1852, Millholland secured a 
patent (No. 8,742) for the combination of dead-plate 
grates and central combustion chamber.'’ The 
17'The central combustion chamber had been patented in 
England six years earlier. See John Dewrance, British Patent, 
October 1846. The central-combustion-chamber boiler was 
revived in 1884 by A. J. Stevens, master mechanic of the 
Central Pacific Railroad. Seemingly unaware that this was 
an old idea, he reported in the January 1885 National Car 
Builder (page 2) on the successful tests of a locomotive boiler 
identical in plan to Millholland’s. The incident aptly il- 
lustrates the many instances of inventors independently du- 
plicating the work of others in attempting to solve identical 
problems. 


Figure 10.—THE ANTHRACITE-BURNING EXPRESS LocoMoTIVE Illinois, built in 1852 by Millholland at the 
Reading Shops. The engine was not a success, but, after remodeling, continued in service until 1869. 
(Smithsonian photo 26807-G.) 
PAPER 69: JAMES MILLHOLLAND AND EARLY RAILROAD ENGINEERING 13 
