Sunday 6 October 2013


One of the major innovations of the 1845 expedition was the conversion of HMS Terror and Erebus to auxiliary steam power (Battersby and Carney 2011).  On his blog, Peter Carney has documented his research on the locomotive engines used in this conversion; he later published his findings in the International Journal for the History of Engineering and Technology (Battersby and Carney 2011). To me, his research strongly indicates that the locomotive engines were not the Planet Type as has traditionally been assumed (e.g Cyriax 1997), but rather the Croydon and Archimedes engines built by G & J Rennie in 1838 and 1839.

Based on Carney’s research, I originally utilized a plan published in Brees (1840:133) which was labeled as the “Croydon” engine. However, in a recent email correspondence, Mr. Carney pointed out that this image was probably incorrectly attributed by Brees. The issue lies in the wheel arrangement and cylinder position. The image I based my locomotive plans on depicts a “0-4-2” engine with outside cylinders, while the Croydon was likely a “2-2-2” engine with inside cylinders (Bradley 1963; see also Carney’sblog). Mr. Carney believes the image I based my plans on probably depicted the “Hercules” engine, which was an assistant engine while the Croydon and Archimedes where passenger locomotives.

I always suspected there was something wrong with the locomotive I used in my original plans. If you look at my previous profile plans, the cylinders actually overlap the position of the spare rudder. Given that the modifications to the 1836 Terror plans show the exact position of the new engine room walls, this obviously could not have been the locomotive installed in 1845 (i.e. the locomotive was simply too big). Mr. Carney kindly pointed me to another image drawn by Brees (1840:306) which is unnamed, but which depicts a 2-2-2 locomotive with inside cylinders that was built by G & J Rennie – a good candidate for Croydon or Archimedes.

Using this new plan and an excellent set of drawings that Mr. Carney created and kindly provided (see his 3D reconstruction), I created my own scale plans of the locomotive. Using the dimensions from Bree’s (1840:14) original report, I scaled this new plan to exactly 1:48 and placed it in the proper position. As you can see, it fits perfectly, with just inches to spare on either side of the engine. To me, this exact spatial correspondence just adds credence to Carney’s theory that Archimedes or Croydon was the locomotive installed on HMS Terror.  

My new plans of the G & J Rennie engine, based on Brees (1840:306),
following the research of Peter Carney. The frame is speculative.  


INCORRECT - My original plan using the Hercules (?) engine. Note
the overlap with the spare rudder.

CORRECT? - The new engine in my updated plans.
Because of the new locomotive engine, the position of the funnel and steam outlet changed significantly, and these are depicted on the new deck plans. Given that the locomotive was only used in calm conditions or to avoid beating, it is likely that the chimney and steam pipe were removable, to conserve space on the crowded deck (Battersby and Carney 2011:202). As a result, I believe a scuttle or hatch system was used when the chimney was not installed, and I based these on one shown in the 1836 Terror deck plans (I have been unable to determine what that 1836 hatch was originally used for – the furnace chimney was apparently installed at the fore hatchway).

The positions of the chimney, steam pipe, and their hatches on my old plans.

The positions of the chimney, steam pipe, and their hatches on my new plans.

Finally, I should note that on my plans the height of the engine’s chimney and steam pipe are based on the following contemporary description (which also accurately describes the location of the chimney and the steam pipe):  

*  Note: Rather than post yet another set of updated plans, I’ve simply updated the plans on a previous blog post. The images have begun to be indexed on search engines and I don’t want to create confusion!




1845    Literary Gazette Journal for the Year 1845. Robson, Levey, and Franklyn, London.

Battersby, William, and Carney, Peter

2011    Equipping HM Ships Erebus and Terror, 1845. International Journal for the History of Engineering & Technology 81(2):192-211.

Bradley, D.L.

1963    Locomotives of the South Eastern Railway. Solihull: Railway Correspondence and Travel Society (1):11–12.

Cyriax, Richard, J.

1997   Sir John Franklin's Last Arctic Expedition: The Franklin Expedition, A Chapter in the History of the Royal Navy. The Arctic Press, West Sussex.



  1. Thank you. Very interesting work. It would be interesting to show these plans to someone experienced in operating steam locos of this vintage to see what they think of the practicability operation. E.g., I was once told that the engine would need its wheels on to act as a flywheel. Was a substitute flywheel fitted?

  2. Hi William,

    Interesting point here. I've seen several reconstructions that show the drive wheel in place. I'm certainly no expert - but looking at the plans, I think it's possible these engines could have been used without the drive wheels in place (I think the pistons articulated with a crankshaft rather than the wheel itself). It would be interesting to hear Peter Carney's take on this - I know the plans on his blog don't show a wheel in place, and he must have had a good reason for that. In any case, I've left the original frame on the engine, so adding the drive wheel would be easy to do if new information comes out.

    But your point is well taken - perhaps I will contact a curator at the Manchester Museum of Science and Industry, who run a replica Planet engine, and pose the question.