This was rapidly taken up by other journals, including "Scientific American", arguing that due to the differances between Nasmyth's sketch and the known appearance of Rocket, that either Rocket had been considerably rebuilt, or there had been two locomotives named Rocket.
Sadly, this argument falls appart when one realises that Nasmyth sketched Northumbrian, not Rocket and that Rocket which now stands in the Science Museum in London is definately Robert Stephenson's Rocket from the Rainhill Trials. There is no need for any conspiracy theories.
Rocket as is appeared c.1900: the snokebox was added and the cylinders lowered during its working life, c.1831.
A second sketch, purporting to show Rocket, this time in 1832 was then published.
Rocket drawn by Mr W Stenson of Leicester on 12 March 1832. But is it Rocket of Rainhill fame?
It's a beautifully detailed sketch. The tender - including the hand brake, brake-gear and water feed pipes - are depicted in great detail. So too what appears to be a lamp on top of the coal rail at the rear. It bears a strong resemblance with the tender of Northumbrian sketched by Nasmyth two years earlier.
But what of the Locomotive? The inclinded cylinders driving the front wheels is clearly of Rocket-type, but we know that by 1832 Rocket was either under repair and was in the process of being refitted with nearly-horizontal cylinders or had been refitted. That said, Rocket was the only one of the Rocket-type locomotives suppled with inclined cylinders. Given that Rocket was rebuilt with lowered cylinders c.1832, this cannot be Rocket of Rainhill. The details of the cylinder (valve chest uppermost) and the valve gear appear to be sketched from life - as does the rest of the locomotive. The boilder, firebox with steam dome surmounted by a Salter safety valve and smokebox are clearly of Planet-type. Boiler fittings including the "pop" safety valve, man hole and even the feed clacks are shown. There are what appear to be splashers over the four-coupled driving wheels. Oh yes, Rocket of Rainhill was a 0-2-2, whilst this locomotive is very clearly not of that wheel arrangement. Given how short Rocket's boiler barrel is, it is unlikely that, even supposing Rocket was to be rebuilt as an 0-4-0 that a second set of 4' 8 1/2" driving wheels could be fitted.
So what is this mystery locomotive?
Clearly, it is not the Rocket of the Rainhill Trials. The closest locomotive which exists today is another Rocket, this time built for export to the USA in 1838 Robert Stephenson & Co.
Here we have a four-coupled locomtoive with inside frames, Stephenson-type boiler and smoke box, and even a steam dome with Salter safety valve... but a Bury-type cylindrical fire-box (as stipulated in the order from Stephenson & Co.) and, crucially,
The inclined cylinders and Planet-type boiler are not unique to this machine, however. Robert Stephenson & Co supplied a very similar locomotive named Eclipse to the Pen-Y-Darren Tramway in 1832
"The Engineer" suggests that Stenson drew this particular Rocket "as she stood on the Fosse lane siding, near Leicester". Now why would Rocket be in Leicester rather than working ballast trains between Liverpool and Manchester? The location would suggest this was a locomotive for the Leicester & Swannington Railway, which did use locomotives supplied by Robert Stephenson & Co. (that is to assume that this particular Rocket was built by them) of the 'Large Samson' 0-4-2 type. None of them were called Rocket.
So what did Stenson draw? Clearly it is not Rocket of Rainhill, and by all accounts was sketched from life in March 1832. The Planet-type boiler and anachronist inclined-cylinders although unusual are not unique to other Stephenson locomotives of the period. Perhaps this is an unkown, unusual early Stephenson machine? We shall never know, but, contrary to the assertion of "The Engineer" over a century ago, it is not Rocket of Rainhill.