It has been announced, that tho vessel which has recently sailed with the now celebrated Dr. Livingstone for the southeast coast of Africa, has on board a peculiar steamboat, provided by the British Government, to enable the veteran traveler to prosecute his investigation of the Zambesi Eiver. This small steamer or launch, has been built at Birken-head, opposite Liverpool, by John Laird, and the material of which it is principally constructed is the "homogeneous metal," noticed on page 149, this volume SCIENTIFIC AMERICAN. The plates for the hull of this steamer will be as strong as those of common iron double the thickness. For convenience of transport, it has been built in three sections. The center section contains the boiler and a single horizontal high-pressure engine of 12-horse power, and the two end sections are fitted up for the accomodation of the persona en- gaged iu the expedition. Each compartment is made secure with water-tight bulkheads. In the aft section is a neat deck-house, which will be comfortably furnished, and will have every necessary appliance for securing ventilation. The vessel is a paddle steamer, her dimensions being—length, 75 feet; breadth, 8 foet; and depth, 3 feet. She will not draw more than 12 or 14 inches, so that she is expected to be able to navigate the shallowest parts of the river. The boiler, as well as the hull of the launch, is made of the homogeneous metal plates, which are only three-tenths of an inch thick. The sections will be joined together and launched when the ship reaches her destination. Great results aro expected from this expedition.