se engines were built in
limited number by nearly every well-known maker, and among the
few remaining is the 6-wheel "Pioneer," on display in the Museum
of History and Technology, Smithsonian Institution. This
locomotive is a true representation of a light passenger
locomotive of 1851 and a historic relic of the mid-nineteenth
century._

THE AUTHOR: _John H. White is associate curator of
transportation in the Smithsonian Institution's Museum of
History and Technology._

The "PIONEER" is an unusual locomotive and on first inspection would
seem to be imperfect for service on an American railroad of the 1850's.
This locomotive has only one pair of driving wheels and no truck, an
arrangement which marks it as very different from the highly successful
standard 8-wheel engine of this period. All six wheels of the _Pioneer_
are rigidly attached to the frame. It is only half the size of an
8-wheel engine of 1851 and about the same size of the 4--2--0 so common
in this country some 20 years earlier. Its general arrangement is that
of the rigid English locomotive which had, years earlier, proven
unsuitable for use on U.S. railroads.

These objections are more apparent than real, for the _Pioneer_, and
other engines of the same design, proved eminently successful when used
in the service for which they were built, that of light passenger
traffic. The _Pioneer's_ rigid wheelbase is no problem, for when it is
compared to that of an 8-wheel engine it is found to be about four feet
less; and its small size is no problem when we realize it was not
intended for heavy service. Figure 2, a diagram, is a comparison of the
_Pioneer_ and a standard 8-wheel locomotive.

Since the service life of the _Pioneer_ was spent on the Cumberland
Valley Railroad, a brief account of that line is necessary to an
understanding of the service history of this locomotive.

_Exhibits of the "Pioneer"_

The _Pioneer_ has been a historic relic since 1901. In the fall
of that year minor repairs were made to the locomotive so that
it might be used in the sesquicentennial celebration at
Carlisle, Pennsylvania. On October 22, 1901, the engine was
ready for service, but as it neared Carlisle a copper flue
burst. The fire was extinguished and the _Pioneer_ was pushed
into town by another engine. In the twentieth century, the
_Pioneer_ was displayed at the Louisiana Purchase Exposition,