A CHASE ACROSS THE BAY.

The suddenness with which the red-whiskered man's accomplices had interfered with Motor Matt's plan, and caused it to fail, was as startling as it was unexpected. Matt, standing back toward the edge of the dock with a thumping pain in his shoulder, felt a spasm of chagrin and disappointment.

McGlory picked himself up, assisted the policeman to his feet, and both came toward Matt. The policeman was rubbing his head, and seemed dazed.

"Sufferin' snakes!" exclaimed McGlory. "I'm trying to figure out what happened. Who were the other two that blew in on us, pard, just as we had everything our own way?"

"They must have been Kinky and Ross," replied Matt.

"Who are they?" demanded the officer.

"Two pals of this red-whiskered man. He probably had them waiting in the background, just as we had you waiting to help us, officer."

"This ain't the last of this!" cried the officer hotly. "Which way did they go?"

Matt indicated the direction. The officer started off at a run, tugging at his pocket.

"Why don't you come along?" he demanded over his shoulder.

"One of them said something about getting away in a launch," returned Matt. "I didn't know but it was a boat that I have here, and I think it's well to stand around and see if they come back."

"I'll see where the scoundrels go, anyhow," said the officer, and vanished at a rapid pace.

"Are you hurt, Joe?" inquired Matt.

"My feelin's are badly injured," answered the cowboy. "The rap I got on the block don't count for much, although it was enough to drop me, right where I stood. They're a fine lot, those galoots. I reckon, it's a cinch that they're the chaps we want—and the ones we won't get. George will weep some more when he hears about it."

"Listen!" said Matt.

The exhaust of an engine struck on his ears, faintly but distinctly. It came from somewhere to the south of the place where he and McGlory were standing.

"What is it, pard?" queried the cowboy.

"A boat! Didn't you hear Red-whiskers speak about a launch?"

"Yes, but I reckoned it was the Sprite he meant, and that he changed his mind when he saw you hustling to get between him and the boat."

"It wasn't the Sprite, but another launch, and—— Ah, see that!"

Matt pointed into the darkness to the southward. A light could be seen moving around the end of a slip, gliding across the dark water like a star.

"There they go!" cried McGlory excitedly.

"This way, Joe," called Matt, whirling and running toward the Sprite. "Hurry!"

The Chinese boy was still dozing by the post, the noise caused by the recent scrimmage not having been sufficiently loud to disturb him. He was on his feet, however, the instant Matt dropped a hand on his shoulder.

"You Motor Matt?" palpitated Ping. "You wantee——"

"Cast off the rope, Ping," cut in Matt, sliding from the edge of the dock into the boat. "Quick! Get in behind, Joe," he added to McGlory. "We haven't an instant to lose."

"Well, hardly," answered the cowboy, scrambling aboard while Matt started the engine. "Time's plenty scarce for us if we're to overhaul that other boat."

The painter fell into the boat and Ping fell along with it.

"I didn't intend to take you, Ping," said Matt, switching the power into the propeller and turning the nose of the Sprite toward the open bay.

"By Klismus," said Ping, with unexpected firmness, "my workee fo' you! Where you makee go, my makee go, allee same. Me plenty fine China boy."

"Got any sand, Ping?" asked McGlory.

"Have got. Fightee allee same like Sam Hill. Whoosh! Plenty big high China boy, allee same Boxer. You watchee, Motol Matt watchee. My workee heap fine fo' Motol Matt. Workee, fightee—him allee same."

While this brief cross-fire was going on between McGlory and Ping, Matt was driving the Sprite down the slip for all she was worth. The water slithered up along her sharp bow and flung itself in spray over the crouching forms of the cowboy and the Chinese. The launch, because of the weight aft, was very much down by the stern; but this, by throwing the bow high, helped the boat to slip over the water.

After dropping from the dock into the launch Matt had not seen the moving light until, when he was halfway out of the slip, the little gleam danced across the open space between the outer ends of the two piers.

"Great spark plugs!" muttered Matt, "that's the other boat."

"She's going north!" exclaimed McGlory.

"Which makes it easy for us to pick up her trail and follow. If she had gone south, she might have got away from us."

"She's rippin' along like an express train," murmured the cowboy, watching the light vanish around the end of the pier.

"She's not speedy enough to leave the Sprite behind," exulted Matt, his nerves quivering in unison with the little tremors the humming cylinders sent through the boat.

"If those tinhorns see us, pard——"

"They won't. We're not carrying any lights, and I'm surprised to see them with one."

"Mebby they can hear us if they can't see us."

"We'll have to drop behind far enough so they won't hear us. Their own boat makes twice as much noise as the Sprite, and that will drown the throb of our exhaust and the whir of the cylinders."

Just then the Sprite dashed out of the black maw of the slip, wheeled in a foamy arc and turned her nose northward. There were many lights in the bay—red and green side lamps and white masthead lights, and others, but Matt was not confused. The white gleam straight to northward was the one he knew he should follow.

A lightish streak surged in the wake of the other launch. Matt could not make out much about the craft except that she was considerably larger than the Sprite and had a canvas or wooden canopy over the cockpit.

But the Sprite was the faster boat. Matt, studying the distance that separated the Sprite from the launch ahead, found it necessary to choke down the motor in order to keep from overhauling the three thieves.

"I thought you wanted to catch them," complained McGlory, conscious of the lessening speed.

"What good would it do for us to overhaul them out in the bay?" queried Matt, humping over the wheel and speaking without turning his head. "There are three of the scoundrels, and they're armed and would probably be only too glad to have us tackle them. If Red-whiskers could lay me by the heels, you know, he'd get his trunk check."

"Correct, pard. It wouldn't do to run alongside of them in the bay. But what're you thinking of?"

"We're just shadowing them to find out where they go. When we discover that, we'll hold a council and decide what's to be done next."

"Waugh!" sputtered McGlory. "Queerest ever that I can't ride on the water without getting a gone feeling in the pit of my stomach."

"Have you got it now, Joe?"

"Awful. If I had any supper aboard, I reckon I'd unload. And I can go through all kinds of rough weather on a buckin' bronk! No matter how much a bronk pitches, or bucks, it never makes me squeamish—but boats! Well, the minute I get into one I begin to have cramps. Funny, ain't it? They got a fake boat in a picture gallery in Tucson, and if a galoot wants a tin type of himself, at sea, he gets into the fake boat and lets the camera snap. Honest to Mack, every time I go to that place for a tin type I get seasick."

Matt laughed.

"And yet you like boats!" he exclaimed.

"Achin' for 'em all the time. It's human nature to be contrary with yourself, I—— Sufferin' centipedes! I'm an Injun if that other boat isn't making for Tiburon."

"I don't think so, Joe," said Matt. "There's a place around the point that's called Belvedere Cove. The other boat is either going to put in there or else go farther up the bay. We can tell in a minute."

A little later Matt announced that the other launch had doubled the point and put into the Cove. For a brief space the point of land hid the larger launch from the eyes of those in the Sprite; but, as the Sprite pushed around the point, a multitude of lights burst suddenly on the gaze of her passengers—stationary lights they were, with the exception of one that was gliding among them like a shooting star.

"Tell me about that!" muttered McGlory, standing up for a better look. "The surface of the cove looks like a town. Where are all those lamps?"

"On houseboats, Joe," replied Matt. "The tide-water inlets, in and about San Francisco Bay, are full of house boats at this season of the year. That's the other launch—that moving light, over there."

McGlory continued to stand up, bracing himself with a hold on Ping's pigtail, which happened to be the most convenient thing handy.

The Sprite, keeping to the trail of the moving white gleam, darted in and out among the house boats. From many of the anchored boats came sounds of mirth, music, and gay talk. Some one, on an ungainly craft which the Sprite passed within a short fathom, shouted a warning for Matt to put out a light. This warning, of course, could not be heeded, and the little launch foamed onward out of earshot.

Suddenly Matt shut off the power and brought the boat to a halt.

"The other launch has tied up alongside a house boat, Joe," he announced, "and we're at the end of our trail. What shall we do? Go to Tiburon after a policeman or two or go on with the work ourselves?"