It was necessary, therefore, to build each boat in six watertight compartments, of 4ft. in length, of one sheet of copper, each of which overlapped the one behind it, just as the scales of a lobster are arranged, making the actual length of the boat 22ft. The “skin” of each section was made of three sheets of copper, 2ft. wide, laid side by side with their edges doubled over each other, so as to make a perfectly turned joint that required no riveting, and was only soldered to render it more certainly watertight. The ends of each section were marked to the curve required, but cut three inches larger, the extra circumference being cut with snips directed toward the centre, so that they might be turned outward to fit the curve of the skin, thus leaving a flange of 3in. at each end of the section, a strip of copper 6in. wide was doubled and slipped over both parts, riveted and soldered, the necessary surfaces having been previously tinned.
We hope the engraving on the next page will make this plan tolerably plain. The end to the right is left unfinished, with the separate pieces a little apart ready to be put together; the farther shows the manner in which the flange of the foremost section overlaps the after, and is bolted to it with copper screws and nuts, leaving a space between, into which the hand and arm could be thrust if it were needful to reach the bottom; the water would flow in or out of this narrow space freely, the compartments only being guarded against leakage; the nuts were all on the inside, and the iron key shown in the sketch was for the purpose of turning them on or off, while the heads were held outside by the screw wrench. The copper was kept in shape by an inner frame of wood, and strengthened externally by seven rib-bands or stringers of good straight grained red deal, running the entire length, of which two served for gunwales and one for the keel, the ends of this being let into sockets formed in the pieces of copper which were doubled over the stem and stern post. One of the connecting beams is shown in this sketch, and also the rings by which the sections were to be carried when separated for overland conveyance.
METHOD OF BUILDING AND CONNECTING SECTION OF COPPER BOAT.
COPPER BOATS ADJUSTED SIDE BY SIDE.
For the purpose of keeping the cargo dry and secure from pilfering, it was necessary that each section should have its own deck, and this, to bear the weight of people standing on it, had to be made of ¾in. plank, covered like the other parts with copper. Around each hatchway were two mouldings, ¾in. high, the hollow between which, in heavy rains, we intended to fill with wax or grease, so that when the corresponding moulding of the hatch fitted into it it might be watertight. The connecting beams were 12ft. long, and made each of two pieces of ¾in. red deal, 2in. wide, so as to afford us, with the platform laid on them, an available deck space of 12ft. by 20ft., on which, when the river was broad and open, we might live or work with comfort; while, if it narrowed, as we expected it would at Kansalo, Chicova, or Kebrabasi, we could separate the boats and take each through singly, towing the deck-raft, or even, if necessary, casting it adrift and trusting to pick it up as the current brought it down. Two ¾in. planks, 9in. deep and 4ft. long, so as to catch the bolts at either end of the section, served to support the rowlocks. Each boat was provided with her own rudder, and we purposed, if necessary, to connect the tillers by a light rod, although we believe she would have steered by one alone. The masts were shipped in a wooden case, between the foremost and the next section, and the mode of setting the lug sails and awning will, we trust, be made sufficiently plain by the engraving. Care had to be taken that no iron or other metal capable of exerting a corrosive action came in contact with any part of the copper that was likely to be wetted. And the reader will pardon us if, while stating that the whole was built piece by piece in a little bedroom scarce 8ft. by 12ft., we take this opportunity of paying a slight tribute of gratitude to our warmhearted friend Frederick Logier, to whose hospitality we were mainly indebted for the means of completing our equipment, and who fell a victim to the fever so fearfully prevalent in Cape Town in October, 1867. The ensign, kindly made for us by a lady of that town, after having floated over our house at Logier Hill, on the Zambesi, and served as the flag of our little artillery corps at Otjimbengue, we still preserve as a relic of the journey.
The difficulties of the road, and deficiency of carriage, which compelled us to leave behind eight out of the twelve sections, and our expedients to replace them, will be more fully described hereafter: we, therefore, append only an abstract of the materials employed in building:—