This... thing... is a conventional steam locomotive mounted on not one but two sets of extra wheels or rollers.
Left: The Holman... Thing.
For some reason I have resisted adding this item to the Locomotive collection for some time- possibly because of a half-formed notion that it was inappropriate to lump this piece of insanity in with the honest efforts of decent engineers. Basically it was designed as a lure in a stock-market swindle.
It was built by the Holman Locomotive Company in 1887 in Philadelphia, and was at once ridiculed by everyone with the slightest knowledge of railways or mechanics. The thing was run for a few trips on a straight railroad in New Jersey, merely as a stimulant to stock sales.
As Angus Sinclair put in 1907:
"When we first heard of the Holman locomotive we supposed that it was the invention of some harmless crank who did not understand the elementary principles of mechanics, but we now believe that it has been, since its inception, an ostentatious machine designed to allure unwary capitalists into an investment which will be of the same real value as throwing gold coin over Niagara Falls."
Left: Detail from a share certificate.
It is far from clear what the advantages of the Holman were supposed to be. Unlike the Fontaine, there seems to be no gearing-up effect that might notionally increase speed, and instead of one place for wheelslip to occur, ie the wheel-rail interface, there are now a whole lot of extra wheel-wheel interfaces. There also looks like a strong probability it would fall over when it tried to move.
Ultimately there seems little point in trying to analyse something that was a financial trap rather than a serious bit of engineering.
Above: Oh no, not again! This Holman system locomotive was built by Baldwin.
It has only recently become clear that there were two Holman locomotives, and the whole business is still very murky. If the first Holman loco was built in 1887 for a stock-market swindle, it seems very strange that the crooks should be ordering another insane loco- with the same very distinctive features- only ten years later. Were they trying exactly the same scam again? If so they they must have thought investors had very short memories. Perhaps they were right.
"Curiosities of Locomotive Design."
from "Development of the Locomotive Engine", by Angus Sinclair.
Railway and Locomotive Engineering (September to December, 1907)