When I said, in the commencement of this letter, that I was swearing before the committees, I made use of a wrong term. We are not sworn--not even examined on soul, or on conscience, or on honour; and I must say that the recollection of that circumstance is sometimes a great comfort when I lie in bed awake of nights. What is technically termed at Westminster, engineering evidence, would, I am afraid, were an oath to be interposed, become very like the thing called perjury; which, not to mention its effect on a future state of existence, is popularly supposed in Scotland to bring one under the unpleasant but especial attention of the High Court of Justiciary. The beauty of the present system is, that it gives ample scope and rein to the imagination without imposing any restrictive fetters upon the conscience. It allows a fair latitude for that difference of opinion which always must prevail amongst professional gentlemen, and relieves them from whatever qualms they might otherwise have left in replying without any hesitation--the leading quality of a witness--to questions upon subjects of which they are utterly and entirely ignorant. I have found this advantage in my own case. I am positive that I could not, had I been on oath, have given any satisfactory evidence as to the amount of the bathing traffic on the line; though I certainly admit that I have sometimes of a Saturday afternoon sauntered along the shore with a cigar, to enjoy the _posés plastiques_ of our northern aquatic Nereids. But as all such formality was dispensed with, I had no hesitation in stating the numbers of the amphibious animals, male and female, at eight hundred per hour during seven months of the year; which, on an average of nine hours a day, and at the rate of sixpence a head, would increase the income of the company by about £37,800 per annum. Such was one item of my evidence yesterday, for the clearness and accuracy of which I was politely complimented by the chairman. I must say, however, that I think Switches went rather too far when he valued poor Pertinax’s garden land at less than half-a-crown per acre. I can make every allowance for enthusiasm; but surely, surely this was pushing the principle a little to the extreme. One ought always to preserve, even for the sake of our employers and paymasters, some little semblance of probability. I do not object to an engineer stating in evidence that he is ready to tunnel Ben Nevis, throw a suspension bridge, over the Queensferry, or convert Lochlomond into a green and fertile meadow. All these--as Switches once observed with consummate coolness when badgered about the draining of a quicksand--are mere matters of estimate; but I like facts when we can have them; and had I been questioned on the subject, I think I should have been inclined to have allowed an additional shilling for the land.