"That depends on the power of the wind, sir. Do you think it is a mad scheme?"

"It would impress the natives," said Compton, "and at any rate we could start wheat-milling, you know, in case we came to the end of our resources."

"There's no wheat in Central Africa, you duffer! Besides, sir, it's mainly a question of gear. With a lever, cog-wheels, and a running chain after the pattern of the cycle chain, one could----"

"And ball bearings," suggested Compton, slyly.

"Yes; and ball bearings--the friction would be reduced, and we could get more power out of a screw and propeller than we could from four paddles."

"You may be right," said Mr. Hume, thoughtfully.

"We don't want to take a large party, and I confess the water transport has bothered me very much. The wind-mill, I am afraid, we must leave to some other time, but the other part of your scheme is worth placing before practical men, and I will give you a letter to a friend of mine who had a boat built on the Thames."

Venning saw the friend the very next day; the friend gave him an introduction to a member of a great firm of torpedo-boat builders on the Thames, and this gentleman very kindly gave the matter five minutes' attention.

"Your idea, eh?" said the great designer. "Explain what advantage you expect to gain."

"Less labour in working than with paddles, and greater speed."

"Humph! Well, my lad, you leave the matter with me, and I will report. You can look over the yards if you like."

Venning spent the rest of the morning among the wicked-looking sharks of the Navy, and he went back depressed with the thought that his "sneak-box" was merely a plaything. However, he picked up confidence when the next day brought an offer from the builders to turn out an aluminium sneak-box in three divisions, with capacity for a crew of six, to be worked on occasion by two men pulling at levers, driving the propeller by means of endless chains and cog- wheels, the gear to be made of best oil-tempered nickel-steel, with hardened ball bearings. Each division, when detached, of such weight that it could be easily carried by three men, but no guarantee given that the propeller would give the speed desired.

"That is good enough for us, I think," said Mr. Hume.

"They give no guarantee," remarked Compton, cautiously.

"No; but they would not undertake the work unless they had some belief in the idea, and if the propeller proves useless, we can at the worst unship it. In any case we must have the boat, and we could not improve on the makers."

The order was given, and by the fourth week the little boat was launched on the Thames for its first trial. It looked workmanlike in spite of its wide beam and shallow draught, for the great designer who had fashioned the lines of the fastest destroyer afloat had himself drawn up the plans after giving a day's careful thought to the job. The shaft, which rested on nickel-steel sockets, with ball bearings supported by nickel-steel ribs for lightness, was protected by a water-tight casing, and all the other parts made of the very best metal, so as to secure both lightness and strength, with a complicated set of cog-wheels to take off the strain. The steering was by a neat wheel right forward, where the look-out man could have an uninterrupted view. Forward, too, was the socket for the metal mast. The boat was fifteen feet in length, with a beam of four feet amidships, tapering fore and aft, with a well in the centre, and the remaining s.p.a.ce covered in with a light aluminium deck, strengthened by oak bends. There was sleeping-room for two, so that with a crew of four there would have to be four watches of three hours each. The peculiar features of the long, low craft were the two levers rising above the after-deck through slots, which gave each a thrust of about one and a half feet, and two saddle-like seats borne on stout supports, one near the stem facing the bows, and the other further forward facing the stem. Venning perched himself on one seat, Compton on the other, one of the hands took the wheel, and Mr. Hume and the designer sat in the well.

Compton's clear-cut face, with well-formed jaws, showed no other sign of interest than a rather amused smile, but Venning's fair features were flushed with excitement and nervous expectation, A man pushed the boat out. It moved at first sluggishly.

"Full speed ahead!" cried out Mr. Hume.

Venning pulled his lever over, and as he shot it back Compton pulled his, the two moving to and fro easily as if they had been rowing a steady stroke.

"She moves, she moves!" cried Mr. Hume, with a shout.

"Take her over the mile," said the designer to the steersman; and he pulled out his watch with exactly the same look of calm interest he showed when presiding over the trial of the fastest craft afloat.

The shining aluminium boat answered to her helm, slipped through the muddy waters in a graceful curve, and then steadied for the straight course.

"Let her go, boys."

The levers worked to and fro with an easy swing; there rose the hum of the chains moving easily below, and the quickened churning of the propeller blades.

The designer glanced from his watch to the bank, which was fast slipping away, and nodded his head at Mr. Hume.

"Easy all. I think she will do;" and he nodded at Venning. "Ten minutes."

"Ten minutes!"

"A mile in ten minutes--six miles an hour!"

"And it was as easy as nothing," said Venning--"wasn't it, d.i.c.k?"

"Like cutting bread," said Compton.

"Very good, I think; but you must remember that she carries no cargo. Now we'll try her with the sail alone, and then with the sail and screw combined, and then with the screw and oars, for you will see that I have fitted row-locks."

Under a fair breeze the boat skimmed along at a merry pace, with no wave worth speaking of; and with the sail and screw she put on an additional four miles, and with the oars an extra three, making from nine to ten miles an hour.

"I congratulate you, Mr. Venning," said the designer, as they stepped out, thoroughly pleased.

"I am sure, sir, we thank you," said the boy, warmly.

"Eight," said Mr. Hume; "and we are thoroughly pleased with the craft, every one of us."

"She is a beauty," put in Compton--"a real beauty; and I think she would be perfect if a light awning could be fixed up over the after- deck."

"That could be done easily.

"It would be an improvement, certainly," said Mr. Hume.

"I will rig up brackets to hold the rods for the awning."

"And we could fix up mosquito curtains round the sides. That is A 1.

Now, what is her name to be?" And Mr. Hume looked at Venning.

He had thought of a name, and was prompt with it--the Okapi.

"And what does that mean?" asked the builder, with a smile.

Venning explained, and the name was adopted.

"Now," said the builder, "if Mr. Venning will come down to-morrow afternoon, my workmen will take the Okapi to pieces in his presence before packing it for delivery in the docks, and explain thoroughly how it is to be put together. I will give orders for several extra plates with fittings to be placed in one of the divisions, so that if you have an accident you will have the material for repairing the mischief. You understand, aluminium cannot be soldered, but you could cover a hole by means of nuts and screws."

Venning was in time next day to receive his instructions, and made in his note-book an outline sketch of each part. While he was so engaged, Mr. Hume, with Compton, were seeing the outfit packed for the steamer, every purchase having been made with great judgment, so that nothing superfluous figured in the list. Their armament consisted of one double express for Mr. Hume, two sporting carbines for the boys, three Mauser revolvers, and one fowling-piece, strong hunting-knives, as well as four Ghoorka knives for cutting a path through the forest. As far as possible all their food-stuff was concentrated in tabloids and essences; each had his own special tin- lined medicine-case, in addition to the common drug-chest; each his own water-bottle of double canvas, a material which, permitting evaporation, keeps the water cool; and each his regulation "billy,"

or cooking-tin. As for clothing, it was a mixture of luxury and rough wear, of the best silk underwear, cellular shirts of a light blue, and yellow chamois-skin breeches, warranted to grow tougher with use. Putties were discarded, as likely to give harbourage to "jiggers," which bore into the toes, in favour of soft leather high boots, tightly fastened at the knee; and the outfit included needles for the making of moccasins, or veld schoen, from the hides of the larger antelope.

"Why do you select all blue shirts, Mr. Hume?" asked Venning.

"On account of the mosquitoes."

"Consider the feeling of the gorillas," said Compton, dryly.

"Perhaps they would prefer green."

"They may find us green enough for their taste, Compton; but I am not joking. Mosquitoes have a preference for some colours and an aversion for others. They dislike blue most of all, so you see I have a purpose in selecting blue--not only for the shirts, but for the mosquito curtains."