The first difficulty, and one which was as unexpected as it was serious, was in the working of our stationary engines. Upon the efficiency of these machines must of course ultimately depend the economy and efficiency of the working of the whole system, however perfect in itself might be the Atmospheric apparatus. Accordingly, great precautions were taken--precautions which I still think such as to justify the expectation that we should secure the best engines that could be made. The three first manufacturers of the day were employed--Messrs. Maudslay (who had had some experience in this particular branch, having made the engines for the Croydon railway), Messrs. Boulton and Watts, and Messrs. Rennie. They prepared their own designs; and I know that they each bestowed much thought in the preparation of these designs, and took considerable interest in the results. Mr. Samuda, a man of considerable mechanical abilities, having all the experience that could be had upon the subject, and deeply interested in the success of the engines, was also employed to superintend their manufacture. Notwithstanding all these precautions, notwithstanding excellent workmanship, these engines have not, on the whole, proved successful; none of them have as yet worked very economically, and some are very extravagant in the consumption of fuel, burning nearly double the quantity of others, while the average is very considerably more than it ought to be. The apparent causes of this excess are various in the different engines, but all resulting more or less apparently from the want of experience in this particular application of power, and from the circumstance of the form of the engines being somewhat novel, and involving slight differences in the proportion and arrangement of the parts; and the consumption of steam being greater than was calculated upon, it has been obtained by a more wasteful expenditure of fuel, and the evil has been aggravated. The difficulty of remedying this state of things has been increased by the consequence of defects in the Atmospheric apparatus, which, causing a much greater demand upon the working of the engines, has delayed, or has entirely prevented, our throwing an engine out of work, to introduce the requisite improvements. Still, so far as this defect in the engines is concerned, there is no doubt that it is susceptible of considerable, if not complete remedy, and that a reduction of one-third may be effected in the consumption of fuel. In the Atmospheric apparatus itself our difficulties have been more numerous. We have suffered from extreme cold, particularly when it followed quickly upon wet.