Central Pacific Railroad Locomotive #173 - Coal or Wood?

Subject: Central Pacific 173 - Coal or Wood?
From: "Paul Quade" pquade@mac.com:

Hi and thanks in advance for even looking at this [message]. I really appreciate there's somebody out there that might even be able to answer this question.

I've been told diamond smokestacks like the one on the Central Pacific 173 engine was to help circulate embers from wood burning and help them continue to burn until they were small enough to be relatively harmless if they still somehow escaped the screening at the top.

Which brings me to the enclosed photograph of the CP 173 [formerly Western Pacific Railroad "H"] which shows the tender with what appears to be coal loaded in it.

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"CPRR Locomotive #173 'Sonoma' 4-4-0 Norris, 1864." ©CPRR.org

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What I find interesting about that is, as I'm sure you're aware, the CP 173 was also the basis for the the "Lilly Belle" the train in Walt Disney's backyard.

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Lilly Belle model train with Walt Disney

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In the [above two] photos you can see Walt's version clearly depicts the train as a wood burner.

So my question is, was the diamond stack on the original CP 173 simply a leftover from wood burning days or was the CP 173 actually able to burn both wood and coal depending on whatever was available?

Just as a side note: I'm a conductor on the Disneyland Railroad and frequently have the pleasure of having the CK Holliday locomotive pulling my train set. I love discussing the evolution of the CP 173, Lilly Belle, and CK Holliday with our guests and this wood vs. coal question has been on my mind lately. Hopefully you might be able to help me sort that out.

—Paul Quade