The long-expected crisis was at hand, and the country was on the verge of war. Jingoism was rampant. Japanese laborers were mobbed on the western slope, Japanese students were hazed out of colleges, and Japanese children stoned away from playgrounds. Editorial pages sizzled with burning words of patriotism; pulpits thundered with invocations to the God of battles and prayers for the perishing of the way of the ungodly. Schoolboy companies were formed and paraded with wooden guns; amateur drum-corps beat time to the throbbing of the public pulse; militia regiments, battalions, and separate companies of infantry and artillery, drilled, practiced, and paraded; while the regular army was rushed to the posts and garrisons of the Pacific Coast, and the navy, in three divisions, guarded the Hawaiian Islands, the Philippines, and the larger ports of western America. For Japan had a million trained men, with transports to carry them, battle-ships to guard them; with the choice of objective when she was ready to strike; and she was displaying a national secrecy about her choice especially irritating to molders of public opinion and lovers of fair play. War was not yet declared by either side, though the Japanese minister at Washington had quietly sailed for Europe on private business, and the American minister at Tokio, with several consuls and clerks scattered around the ports of Japan, had left their jobs hurriedly, for reasons connected with their general health. This was the situation when the cabled news from Manila told of the staggering into port of the scout cruiser Salem with a steward in command, a stoker at the wheel, the engines in charge of firemen, and the captain, watch-officers, engineers, seamen gunners, and the whole fighting force of the ship stricken with a form of partial blindness which in some cases promised to become total.

The cruiser was temporarily out of commission and her stricken men in the hospital; but by the time the specialists had diagnosed the trouble as amblyopia, from some sudden shock to the optic nerve—followed in cases by complete atrophy, resulting in amaurosis—another ship came into Honolulu in the same predicament. Like the other craft four thousand miles away, her deck force had been stricken suddenly and at night. Still another, a battle-ship, followed into Honolulu, with fully five hundred more or less blind men groping around her decks; and the admiral on the station called in all the outriders by wireless. They came as they could, some hitting sand-bars or shoals on the way, and every one crippled and helpless to fight. The diagnosis was the same—amblyopia, atrophy of the nerve, and incipient amaurosis; which in plain language meant dimness of vision increasing to blindness.

Then came more news from Manila. Ship after ship came in, or was towed in, with fighting force sightless, and the work being done by the "black gang" or the idlers, and each with the same report—the gradual dimming of lights and outlines as the night went on, resulting in partial or total blindness by sunrise. And now it was remarked that those who escaped were the lower-deck workers, those whose duties kept them off the upper deck and away from gunports and deadlights. It was also suggested that the cause was some deadly attribute of the night air in these tropical regions, to which the Americans succumbed; for, so far, the coast division had escaped.

In spite of the efforts of the Government, the Associated Press got the facts, and the newspapers of the country changed the burden of their pronouncements. Bombastic utterances gave way to bitter criticism of an inefficient naval policy that left the ships short of fighters in a crisis. The merging of the line and the staff, which had excited much ridicule when inaugurated, now received more intelligent attention. Former critics of the change not only condoned it, but even demanded the wholesale granting of commissions to skippers and mates of the merchant service; and insisted that surgeons, engineers, paymasters, and chaplains, provided they could still see to box the compass, should be given command of the torpedo craft and smaller scouts. All of which made young Surgeon Metcalf, on waiting orders at San Francisco, smile sweetly and darkly to himself: for his last appointment had been the command of a hospital ship, in which position, though a seaman, navigator, and graduate of Annapolis, he had been made the subject of newspaper ridicule and official controversy, and had even been caricatured as going into battle in a ship armored with court-plaster and armed with hypodermic syringes.

Metcalf had resigned as ensign to take up the study and practice of medicine, but at the beginning of the war scare had returned to his first love, relinquishing a lucrative practice as eye-specialist to tender his services to the Government. And the Government had responded by ranking him with his class as junior lieutenant, and giving him the aforesaid command, which he was glad to be released from. But his classmates and brother officers had not responded so promptly with their welcome, and Metcalf found himself combating a naval etiquette that was nearly as intolerant of him as of other appointees from civil life. It embittered him a little, but he pulled through; for he was a likable young fellow, with a cheery face and pleasant voice, and even the most hide-bound product of Annapolis could not long resist his personality. So he was not entirely barred out of official gossip and speculations, and soon had an opportunity to question some convalescents sent home from Honolulu. All told the same story and described the same symptoms, but one added an extra one. An itching and burning of the face had accompanied the attack, such as is produced by sunburn.

"And where were you that night when it came?" asked Metcalf, eagerly.

"On the bridge with the captain and watch-officers. It was all hands that night. We had made out a curious light to the north'ard, and were trying to find out what it was."

"What kind of a light?"

"Well, it was rather faint, and seemed to be about a mile away. Sometimes it looked red, then green, or yellow, or blue."

"And then it disappeared?"

"Yes, and though we steamed toward it with all the searchlights at work, we never found where it came from."

"What form did it take—a beam or a glow?"

"It wasn't a glow—radiation—and it didn't seem to be a beam. It was an occasional flash, and in this sense was like a radiation—that is, like the spokes of a wheel, each spoke with its own color. But that was at the beginning. In three hours none of us could have distinguished colors."

Metcalf soon had an opportunity to question others. The first batch of invalid officers arrived from Manila, and these, on being pressed, admitted that they had seen colored lights at the beginning of the night. These, Metcalf remarked, were watch-officers, whose business was to look for strange lights and investigate them. But one of them added this factor to the problem.

"And it was curious about Brainard, the most useless and utterly incompetent man ever graduated. He was so near-sighted that he couldn't see the end of his nose without glasses; but it was he that took the ship in, with the rest of us eating with our fingers and asking our way to the sick-bay."

"And Brainard wore his glasses that night?'" asked Metcalf.

"Yes; he couldn't see without them. It reminds me of Nydia, the blind girl who piloted a bunch out of Pompeii because she was used to the darkness. Still, Brainard is hardly a parallel."

"Were his glasses the ordinary kind, or pebbles?"

"Don't know. Which are the cheapest? That's the kind."

"The ordinary kind."

"Well, he had the ordinary kind—like himself. And he'll get special promotion. Oh, Lord! He'll be jumped up a dozen numbers."

"Well," said Metcalf, mysteriously, "perhaps not. Just wait."

Metcalf kept his counsel, and in two weeks there came Japan's declaration of war in a short curt note to the Powers at Washington. Next day the papers burned with news, cabled via St. Petersburg and London, of the sailing of the Japanese fleet from its home station, but for where was not given—in all probability either the Philippines or the Hawaiian Islands. But when, next day, a torpedo-boat came into San Francisco in command of the cook, with his mess-boy at the wheel, conservatism went to the dogs, and bounties were offered for enlistment at the various navy-yards, while commissions were made out as fast as they could be signed, and given to any applicant who could even pretend to a knowledge of yachts. And Surgeon George Metcalf, with the rank of junior lieutenant, was ordered to the torpedo-boat above mentioned, and with him as executive officer a young graduate of the academy, Ensign Smith, who with the enthusiasm and courage of youth combined the mediocrity of inexperience and the full share of the service prejudice against civilians.

This prejudice remained in full force, unmodified by the desperate situation of the country; and the unstricken young officers filling subordinate positions on the big craft, while congratulating him, openly denied his moral right to a command that others had earned a better right to by remaining in the service; and the old jokes, jibes, and satirical references to syringes and sticking-plaster whirled about his head as he went to and fro, fitting out his boat and laying in supplies. And when they learned—from young Mr. Smith—that among these supplies was a large assortment of plain-glass spectacles, of no magnifying power whatever, the ridicule was unanimous and heartfelt; even the newspapers taking up the case from the old standpoint and admitting that the line ought to be drawn at lunatics and foolish people. But Lieutenant Metcalf smiled and went quietly ahead, asking for and receiving orders to scout.

He received them the more readily, as all the scouts in the squadron, including the torpedo-flotilla and two battle-ships, had come in with blinded crews. Their stories were the same—they had all seen the mysterious colored lights, had gone blind, and a few had felt the itching and tingling of sunburn. And the admiral gleaned one crew of whole men from the fleet, and with it manned his best ship, the Delaware.

Metcalf went to sea, and was no sooner outside the Golden Gate than he opened his case of spectacles, and scandalized all hands, even his executive officer, by stern and explicit orders to wear them night and day, putting on a pair himself as an example.

A few of the men attested good eyesight; but this made no difference, he explained. They were to wear them or take the consequences, and as the first man to take the consequences was Mr. Smith, whom he sent to his room for twenty-four hours for appearing on deck without them five minutes afterward, the men concluded that he was in earnest and obeyed the order, though with smiles and silent ridicule. Another explicit command they received more readily: to watch out for curious-looking craft, and for small objects such as floating casks, capsized tubs or boats, et cetera. And this brought results the day after the penitent Smith was released. They sighted a craft without spars steaming along on the horizon and ran down to her. She was a sealer, the skipper explained, when hailed, homeward bound under the auxiliary. She had been on fire, but the cause of the fire was a mystery. A few days before a strange-looking vessel had passed them, a mile away. She was a whaleback sort of a hull, with sloping ends, without spars or funnels, only a slim pole amidships, and near its base a projection that looked like a liner's crow's-nest. While they watched, their foremast burst into flames, and while they were rigging their hose the mainmast caught fire. Before this latter was well under way they noticed a round hole burnt deeply into the mast, of about four inches diameter. Next, the topsides caught fire, and they had barely saved their craft, letting their masts burn to do so.

"Was it a bright, sunshiny day?" asked Metcalf.

"Sure. Four days ago. He was heading about sou'west, and going slow."

"Anything happen to your eyesight?"

"Say—yes. One of my men's gone stone blind. Thinks he must have looked squarely at the sun when he thought he was looking at the fire up aloft."

"It wasn't the sun. Keep him in utter darkness for a week at least. He'll get well. What was your position when you met that fellow?"

"About six hundred miles due nor'west from here."

"All right. Look out for Japanese craft. War is declared."

Metcalf plotted a new course, designed to intercept that of the mysterious craft, and went on, so elated by the news he had heard that he took his gossipy young executive into his confidence.

"Mr. Smith," he said, "that sealer described one of the new seagoing submersibles of the Japanese, did he not?"

"Yes, sir, I think he did—a larger submarine, without any conning-tower and the old-fashioned periscope. They have seven thousand miles' cruising radius, enough to cross the Pacific."

By asking questions of various craft, and by diligent use of a telescope, Metcalf found his quarry three days later—a log-like object on the horizon, with the slim white pole amidships and the excrescence near its base.

"Wait till I get his bearing by compass," said Metcalf to his chief officer, "then we'll smoke up our specs and run down on him. Signal him by the International Code to put out his light, and to heave to, or we'll sink him."

Mr. Smith bowed to his superior, found the numbers of these commands in the code book, and with a string of small flags at the signal-yard, and every man aboard viewing the world darkly through a smoky film, the torpedo-boat approached the stranger at thirty knots. But there was no blinding glare of light in their eyes, and when they were within a hundred yards of the submersible, Metcalf removed his glasses for a moment's distinct vision. Head and shoulders out of a hatch near the tube was a man waving a white handkerchief. He rang the stopping bells.

"He surrenders, Mr. Smith," he said, joyously, "and without firing a torpedo!"

He examined the man through the telescope and laughed.

"I know him," he said. Then funneling his hands, he hailed:

"Do you surrender to the United States of America?"

"I surrender," answered the man. "I am helpless."

"Then come aboard without arms. I'll send a boat."

A small dinghy-like boat was dispatched, and it returned with the man, a Japanese in lieutenant's uniform, whose beady eyes twinkled in alarm as Metcalf greeted him.

"Well, Saiksi, you perfected it, didn't you?—my invisible searchlight, that I hadn't money to go on with."

The Jap's eyes sought the deck, then resumed their Asiatic steadiness.

"Metcalf—this you," he said, "in command? I investigated and heard you had resigned to become a doctor."

"But I came back to the service, Saiksi. Thanks to you and your light—my light, rather—I am in command here in place of men you blinded. Saiksi, you deserve no consideration from me, in spite of our rooming together at Annapolis. You took—I don't say stole—my invention, and turned it against the country that educated you. You, or your confrÈres, did this before a declaration of war. You are a pirate, and I could string you up to my signal-yard and escape criticism."

"I was under orders from my superiors, Captain Metcalf."

"They shall answer to mine. You shall answer to me. How many boats have you equipped with my light?"

"There are but three. It is very expensive."

"One for our Philippine squadron, one for the Hawaiian, and one for the coast. You overdid things, Saiksi. If you hadn't set fire to that sealer the other day, I might not have found you. It was a senseless piece of work that did you no good. Oh, you are a sweet character! How do you get your ultraviolet rays—by filtration or prismatic dispersion?"

"By filtration."

"Saiksi, you're a liar as well as a thief. The colored lights you use to attract attention are the discarded rays of the spectrum. No wonder you investigated me before you dared flash such a decoy! Well, I'm back in the navy, and I've been investigating you. As soon as I heard of the first symptom of sunburn, I knew it was caused by the ultraviolet rays, the same as from the sun; and I knew that nothing but my light could produce those rays at night time. And as a physician I knew what I did not know as an inventor—the swift amblyopia that follows the impact of this light on the retina. As a physician, too, I can inform you that your country has not permanently blinded a single American seaman or officer. The effects wear off."

The Jap gazed stolidly before him while Metcalf delivered himself of this, but did not reply.

"Where is the Japanese fleet bound?" he asked, sternly.

"I do not know."

"And would not tell, whether you knew or not. But you said you were helpless. What has happened to you? You can tell that."

"A simple thing, Captain Metcalf. My supply of oil leaked away, and my engines must work slowly. Your signal was useless; I could not have turned on the light."

"You have answered the first question. You are far from home without a mother-ship, or she would have found you and furnished oil before this. You have come thus far expecting the fleet to follow and strike a helpless coast before your supplies ran out."

Again the Jap's eyes dropped in confusion, and Metcalf went on.

"I can refurnish your boat with oil, my engineer and my men can handle her, and I can easily learn to manipulate your—or shall I say our—invisible searchlight. Hail your craft in English and order all hands on deck unarmed, ready for transshipment to this boat. I shall join your fleet myself."

A man was lounging in the hatchway of the submersible, and this man Saiksi hailed.

"Ae-hai, ae-hai, Matsu. We surrender. We are prisoner. Call up all men onto the deck. Leave arms behind. We are prisoner."

They mustered eighteen in all, and in half an hour they were ironed in a row along the stanchioned rail of the torpedo-boat.

"You, too, Saiksi," said Metcalf, coming toward him with a pair of jingling handcuffs.

"Is it not customary, Captain Metcalf," said the Jap, "to parole a surrendered commander?"

"Not the surrendered commander of a craft that uses new and deadly weapons of war unknown to her adversary, and before the declaration of war. Hold up your hands. You're going into irons with your men. All Japs look alike to me, now."

So Lieutenant Saiksi, of the Japanese navy, was ironed beside his cook and meekly sat down on the deck. With the difference of dress, they really did look alike.

Metcalf had thirty men in his crew. With the assistance of his engineer, a man of mechanics, he picked eighteen of this crew and took them and a barrel of oil aboard the submersible. Then for three days the two craft lay together, while the engineer and the men familiarized themselves with her internal economy—the torpedo-tubes, gasoline-engines, storage-batteries, and motors; and the vast system of pipes, valves, and wires that gave life and action to the boat—and while Metcalf experimented with the mysterious searchlight attached to the periscope tube invented by himself, but perfected by others. Part of his investigation extended into the night. Externally, the light resembled a huge cup about two feet in diameter, with a thick disk fitted around it in a vertical plane. This disk he removed; then, hailing Smith to rig his fire-hose and get off the deck, he descended the hatchway and turned on the light, viewing its effects through the periscope. This, be it known, is merely a perpendicular, non-magnifying telescope that, by means of a reflector at its upper end, gives a view of the seascape when a submarine boat is submerged. And in the eyepiece at its base Metcalf beheld a thin thread of light, of such dazzling brilliancy as to momentarily blind him, stretch over the sea; but he put on his smoked glasses and turned the apparatus, tube and all, until the thin pencil of light touched the end of the torpedo-boat's signal-yard. He did not need to bring the two-inch beam to a focus; it burst into flame and he quickly shut off the light and shouted to Smith to put out the fire—which Smith promptly did, with open comment to his handful of men on this destruction of Government property.

"Good enough!" he said to Smith, when next they met. "Now if I'm any good I'll give the Japs a taste of their own medicine."

"Take me along, captain," burst out Smith in sudden surrender. "I don't understand all this, but I want to be in it."

"No, Mr. Smith. The chief might do your work, but I doubt that you could do his. I need him; so you can take the prisoners home. You will undoubtedly retain command."

"Very good, sir," answered the disappointed youngster, trying to conceal his chagrin.

"I don't want you to feel badly about it. I know how you all felt toward me. But I'm on a roving commission. I have no wireless apparatus and no definite instructions. I've been lampooned and ridiculed in the papers, and I'm going to give them my answer—that is, as I said, if I'm any good. If I'm not I'll be sunk."

So when the engineer had announced his mastery of his part of the problem, and that there was enough of gasoline to cruise for two weeks longer, Smith departed with the torpedo-boat, and Metcalf began his search for the expected fleet.

It was more by good luck than by any possible calculation that Metcalf finally found the fleet. A steamer out of San Francisco reported that it had not been heard from, and one bound in from Honolulu said that it was not far behind—in fact had sent a shot or two. Metcalf shut off gasoline, waited a day, and saw the smoke on the horizon. Then he submerged to the awash condition, which in this boat just floated the searchlight out of water; and thus balanced, neither floating nor sinking nor rolling, but rising and falling with the long pulsing of the ground-swell, he watched through the periscope the approach of the enemy.

It was an impressive spectacle, and to a citizen of a threatened country a disquieting one. Nine high-sided battle-ships of ten-gun type—nine floating forts, each one, unopposed, able to reduce to smoking ruin a city out of sight of its gunners; each one impregnable to the shell fire of any fortification in the world, and to the impact of the heaviest torpedo yet constructed—they came silently along in line-ahead formation, like Indians on a trail. There were no compromises in this fleet. Like the intermediate batteries of the ships themselves, cruisers had been eliminated and it consisted of extremes, battle-ships, and torpedo-boats, the latter far to the rear. But between the two were half a dozen colliers, repair, and supply ships.

Night came down before they were near enough for operations, and Metcalf turned on his invisible light, expanding the beam to embrace the fleet in its light, and moved the boat to a position about a mile away from its path. It was a weird picture now showing in the periscope: each gray ship a bluish-green against a background of black marked here and there by the green crest of a breaking sea. Within Metcalf's reach were the levers, cranks, and worms that governed the action of the periscope and the light; just before him were the vertical and horizontal steering-wheels; under these a self-illuminating compass, and at his ear a system of push-buttons, speaking-tubes, and telegraph-dials that put him in communication with every man on the boat, each one of whom had his part to play at the proper moment, but not one of whom could see or know the result. The work to be done was in Metcalf's hands and brain, and, considering its potentiality, it was a most undramatic performance.

He waited until the leading flag-ship was within half a mile of being abreast; then, turning on a hanging electric bulb, he held it close to the eyepiece of the periscope, knowing that the light would go up the tube through the lenses and be visible to the fleet. And in a moment he heard faintly through the steel walls the sound transmitted by the sea of a bugle-call to quarters. He shut off the bulb, watched a wandering shaft of light from the flag-ship seeking him, then contracted his own invisible beam to a diameter of about three feet, to fall upon the flag-ship, and played it back and forth, seeking gun ports and apertures and groups of men, painting all with that blinding light that they could not see, nor immediately sense. There was nothing to indicate that he had succeeded; the faces of the different groups were still turned his way, and the futile searchlight still wandered around, unable to bring to their view the white tube with its cup-like base.

Still waving the wandering beam of white light, the flag-ship passed on, bringing along the second in line, and again Metcalf turned on his bulb. He heard her bugle-call, and saw, in varied shades of green, the twinkling red and blue lights of her masthead signals, received from the flag-ship and passed down the line. And again he played that green disk of deadly light upon the faces of her crew. This ship, too, was seeking him with her searchlight, and soon, from the whole nine, a moving network of brilliant beams flashed and scintillated across the sky; but not one settled upon the cause of their disquiet.

Ship after ship passed on, each with its bugle-call to quarters, each with its muster of all hands to meet the unknown emergency—the menace on a hostile coast of a faint white light on the port beam—but not one firing a shot or shell; there was nothing to fire at. And with the passing of the last of the nine Metcalf listened to a snapping and a buzzing overhead that told of the burning out of the carbons in the light.

"Good work for the expenditure," he murmured, wearily. "Let's see—two carbons and about twenty amperes of current, against nine ships at ten millions apiece. Well, we'll soon know whether or not it worked."

While an electrician rigged new carbons he rested his eyes and his brain; for the mental and physical strain had been severe. Then he played the light upon the colliers and supply ships as they charged by, disposing of them in the same manner, and looked for other craft of larger menace. But there were none, except the torpedo contingent, and these he decided to leave alone. There were fifteen of them, each as speedy and as easily handled as his own craft; and already, apprised by the signaled instructions from ahead, they were spreading out into a fan-like formation, and coming on, nearly abreast.

"The jig's up, chief," he called through a tube to the engineer. "We'll get forty feet down until the mosquitoes get by. I'd like to take a chance at them but there are too many. We'd get torpedoed, surely."

Down went the diving rudder, and, with a kick ahead of the engine, the submersible shot under, heading on a course across the path of the fleet, and in half an hour came to the surface. There was nothing in sight, close by, either through the periscope or by direct vision, and Metcalf decided to make for San Francisco and report.

It was a wise decision, for at daylight he was floundering in a heavy sea and a howling gale from the northwest that soon forced him to submerge again for comfort. Before doing so, however, he enjoyed one good look at the Japanese fleet, far ahead and to port. The line of formation was broken, staggered, and disordered; and, though the big ships were making good weather of it, they were steering badly, and on one of them, half-way to the signal-yard, was the appeal for help that ships of all nations use and recognize—the ensign, upside-down. Under the lee of each ship was snuggled a torpedo-boat, plunging, rolling, and swamped by the breaking seas that even the mighty bulk to windward could not protect them from. And even as Metcalf looked, one twisted in two, her after funnels pointing to port, her forward to starboard, and in ten seconds had disappeared.

Metcalf submerged and went on at lesser speed, but in comfort and safety. Through the periscope he saw one after the other of the torpedo-craft give up the fight they were not designed for, and ship after ship hoist that silent prayer for help. They yawed badly, but in some manner or other managed to follow the flag-ship, which, alone of that armada, steered fairly well. She kept on the course for the Golden Gate.

Even submerged Metcalf outran the fleet before noon, and at night had dropped it, entering the Golden Gate before daylight, still submerged, not only on account of the troublesome turmoil on the surface, but to avoid the equally troublesome scrutiny of the forts, whose searchlights might have caught him had he presented more to their view than a slim tube painted white. Avoiding the mines, he picked his way carefully up to the man-of-war anchorage, and arose to the surface, alongside the Delaware, now the flag-ship, as the light of day crept upward in the eastern sky.

"We knew they were on the coast," said the admiral, a little later, when Metcalf had made his report on the quarter-deck of the Delaware. "But about this light? Are you sure of all this? Why, if it's so, the President will rank you over us all. Mr. Smith came in with the prisoners, but he said nothing of an invisible light—only of a strong searchlight with which you set fire to the signal-yard."

"I did not tell him all, admiral," answered Metcalf, a little hurt at the persistence of the feeling. "But I'm satisfied now. That fleet is coming on with incompetents on the bridge."

"Well, we'll soon know. I've only one ship, but it's my business to get out and defend the United States against invaders, and as soon as I can steam against this gale and sea I'll go. And I'll want you, too. I'm short-handed."

"Thank you, sir. I shall be glad to be with you. But wouldn't you like to examine the light?"

"Most certainly," said the admiral; and, accompanied by his staff, he followed Metcalf aboard the submersible.

"It is very simple," explained Metcalf, showing a rough diagram he had sketched. "You see he has used my system of reflectors about as I designed it. The focus of one curve coincides with the focus of the next, and the result is a thin beam containing nearly all the radiations of the arc."

"Very simple," remarked the admiral, dryly. "Very simple indeed. But, admitting this strong beam of light that, as you say, could set fire to that sealer, and be invisible in sunshine, how about the beam that is invisible by night? That is what I am wondering about."

"Here, sir," removing the thick disk from around the light. "This contains the prisms, which refract the beam entirely around the lamp; and disperse it into the seven colors of the spectrum. All the visible light is cut out, leaving only the ultraviolet rays, and these travel as fast and as far, and return by reflection, as though accompanied by the visible rays."

"But how can you see it?" asked an officer. "How is the ship it is directed at made visible?"

"By fluorescence," answered Metcalf. "The observer is the periscope itself. Any of the various fluorescing substances placed in the focus of the object-glass, or at the optical image in front of the eyepiece, will show the picture in the color peculiar to the fluorescing material. The color does not matter."

"More simple still," laughed the admiral. "But how about the colored lights they saw?"

"Simply the discarded light of the spectrum. By removing this cover on the disk, the different colored rays shoot up. That was to attract attention. I used only white light through the periscope."

"And it was this invisible light that blinded so many men, which in your hands blinded the crews of the Japanese?" asked the admiral.

"Yes, sir. The ultraviolet rays are beneficial as a germicide, but are deadly if too strong."

"Lieutenant Metcalf," said the admiral, seriously, "your future in the service is secure. I apologize for laughing at you; but now that it's over and you've won, tell us about the spectacles."

"Why, admiral," responded Metcalf, "that was the simplest proposition of all. The whole apparatus—prisms, periscope, lenses, and the fluorescing screen—are made of rock crystal, which is permeable to the ultraviolet light. But common glass, of which spectacles are made, is opaque to it. That is why near-sighted men escaped the blindness."

"Then, unless the Japs are near-sighted, I expect an easy time when I go out."

But the admiral did not need to go out and fight. Those nine big battle-ships that Japan had struggled for years to obtain, and the auxiliary fleet of supply and repair ships to keep them in life and health away from home, caught on a lee shore in a hurricane against which the mighty Delaware could not steam to sea, piled up one by one on the sands below Fort Point; and, each with a white flag replacing the reversed ensign, surrendered to the transport or collier sent out to take off the survivors.