'Double Engines'

[USS ALASKA]

From the Richmond Dispatch, 2/13/1862, p. 3, c. 5

Important Purchase by the Government.

We learn that Messrs. Talbott & Brother, proprietors of the extensive foundry corner of 17th and Cary streets, in this city, have sold out their entire establishment to the Navy Department. The sale includes the machinery and tools of all kinds, stock on hand, work completed and manufacturing material, with a lease of the buildings. An officer of the Navy has been appointed general superintendent. This establishment has recently finished and sent off five double engines for gun-boats constructing at a point which we need not mention.

What exactly is a 'double engine'?

Anyone know which gun-boats?

Thanks,
USS ALASKA

 

[AndyHall]

Possibly a reference to compound engines, that were the hot new thing at time?

 

[Mark F. Jenkins]

Also, individual cylinders tended to be called "engines," so a paddlewheeler with two cylinders could be said to have two "engines." But this being Richmond, I'd tend to guess Andy's right on the compound engine (which, if I understand correctly, consisted of a high-pressure cylinder and then the steam went into a low pressure cylinder for further expansion).

 

[captaindrew]

Same as a steam engine train, the actual engine or engines are the cylinders that push the rods that do the work. The boiler provides the steam(fuel) to run the engines. The old horse drawn fire "engines" were steam powered pumps(engines), where the term fire engine comes from.

 

[JohnDLittlefield]

I have run across several references to small "double engines." Other references described the engines in more detail; as having two cylinders. That simple I believe.