It is to be observed that this includes Mr. Field’s apparatus for changing water, Kingston’s cocks, casing the cylinders, and all those extras which were applied to the ‘Great Western,’ and also the paddle-beams and paddle-wheels. Without these latter the nett cost of the engine, fixed in place, and including all other extras, would appear to be about 40,000_l._ or 40,500_l._ If the cylinders be increased to 77¾, which would be equivalent to the pair of 110 inch, and supposing the cost of the engines to increase in the same ratio as the power resulting from this increase, but which ought not to be the case, the total cost, according to Messrs. Maudslay’s estimate, will be 46,500_l._, and deducting the paddle-beams or framework for carrying the paddles, which do not, I think, form part of Mr. Humphrys’ estimate, probably about 45,500_l._ as compared with Mr. Humphrys’ estimate of 30,700_l._ With respect to this latter estimate, I cannot help expressing the fears I entertain that Mr. Humphrys is over-sanguine, and that the cost would greatly exceed the sum named. The items seem to me to be moderate prices only for each article named, and I see no allowance for those alterations, damages, and waste of parts, and a variety of other contingencies, which in a piece of machinery of this magnitude and novelty is certain to amount to a very large sum. In his estimate of the fittings and smaller parts, I think also he has greatly underrated them.