Mr. Betts, the great railway contractor, who has just left for Montreal, is a Director in the Eastern Navigation Company, who are constructing the Leviathan Steamship, for the purpose of facilitating ocean navigation. The other head of this company is the Earl of Yarborough, and the names of Mr. Peto and others of equal note, are also associated with Mr. Betts in the direction. This Company has laid the scheme for a monster steamer, whose dimensions are given as follows:— Length 673 feet; breadth 80 feet; out to out of wheel-houses 120 feet; depth of holt! from combinings of main deck 60 feet'; power of engines 6.000 horse. Her decks present an area of 1J acres of surface, The ship is being built by Scott Russell, Esq., the greatest naval architect ot England, and is constructed in separate compartments, made water-tight), so that in case of her bow or stern breaking off, she would still be able to float in separate pieces. It is doubtful if such a steamer could enter our harbor, and Halifax is therefore regarded as the most suitable port lor this new move in ocean navigation. This steamer is to sail from Milford Haven, where she is now building—or from Holyhead Harbor, which promises eventually to become the great steamship terminus of the British Isle.— — [London paper. [So it seems this great steamer is actually being built. Well, we would like to see it, the experiment is certainly a magnificent one. In connection with the above, we learn by the " Montreal Herald," that Robert Stephenson, the celebrated engineer who built the Britannia Tubular Bridge, is now in Montreal to build a tubular bridge over the St. Lawrence.