By Isaac Ogden Rankin

John Paul Gregg had a hobby. Nobody could doubt it who was with him, even though he did not happen to hear one of the other boys call him “Specific Gravity,” or “Fic,” for short. Gravity Gregg it was and continued to be until it got into the newspapers, and now it is probably settled upon him for life.

When he was a baby he was always investigating the why and the wherefore and more particularly the how of everything he could get his chubby hands on. If he saw anything moving, especially, he always wanted to know why it moved—a curiosity which cost him a finger before he was ten years old.

He was a pretty good all-round student, but it was in the natural philosophy class that he shone. He had picked up somewhere an old copy of a standard book on physics, and his use of the information he had gathered from it caused terror to the good lady who had charge of the department in the village school.

He was apt, for instance, to complicate her mild and innocent experiments by suggesting new applications of the principle involved; and the amount of broken apparatus which went down to his account in the laboratory where the boys were sometimes allowed to work made his mother sigh.

His devotion to physics seemed very unpractical to quiet Mrs. Gregg, who had set her heart on making a minister of her eldest son. She had named him John Paul, by way of having the names of two apostles ready for the future, and she had day-dreams of sitting in the front pew in church to hear him preach, while she looked up to him with wondering delight.

It was a trial to be thinking of the Rev. John Paul Gregg, a tall, dignified and grave man, who was respected by everybody and had, perhaps, published a book of sermons, and then to have a freckled lad, round-faced and brown as a berry, with a scar across his forehead where an exploding crucible had just missed the eye, burst in upon her to beg her best preserving-kettle for an experiment. And to hear the future clergyman called “Fic” Gregg all over her end of the town made her shudder.

Most of the people of Lavenham who knew him thought Specific Gravity mildly insane, but they all liked him. He was so simple and sincere and kind that they could not help it; but they never knew what he would be up to next in the line of dangerous experiment. He was as inventive as a fox, as spry as a cat, and as steady-headed as a monkey.

Old Deacon Podgers looked out at his window one morning when it was blowing half a gale, and on the top of the unfinished steeple of the new Baptist Church saw a strange black object. The deacon, who had been a sea-captain all his active days, turned to the wall for his spy glass, and recognized Gravity Gregg, who had climbed up there to study the vibration of materials, as he told the deacon when he asked him why he risked his life so recklessly.

John Paul acquired his name of Specific Gravity from an early answer in the philosophy class, but it did not become publicly his until one day after an anxious night in the big railroad freight-yards just outside the town.

The Gregg house was on the brow of the hill overlooking the river and the flats where the railroad runs, and Fic knew every landmark visible from his window.

It was a holiday. He had been fishing all day and went to bed early, but woke up about midnight with a start to see a flickering light reflected on the wall. He was at the window in a moment, and after taking an observation said to himself, “That’s in the freight-yards! It must be a car on fire!”

It was not a big blaze, like a burning house, but a flickering little blaze, like that of the lamps on the fruit-peddlers’ stands at night.

The desire to investigate was strong upon John Paul. His mother had never objected to his going to fires, but would she let him go so late at night? He would not wake her up to ask, and with a sigh went back to bed again and dropped off to sleep—only to be wakened up by the distant sound of a fire-engine rattling through the streets and to see the same flickering light at the same spot on the wall.

He went to the window again and took the field-glass, which was one of his most cherished possessions.

“It’s a car, sure enough, and they’ve got the engines out,” he said. “I wish I could go and see.”

He went back to bed, but tossed and tossed, while the light still flickered on the wall.

“It’s strange they don’t put it out,” he thought. “They must have been at work at it two or three hours.”

He rose again and went to the window, but the air was so cold that he dressed himself, his curiosity all the while growing stronger. Taking his shoes in his hand he went softly down to the door, took the spare latch-key from its hook, let himself quietly out, put on his shoes, and slipped down to the front gate.

It was a windy night, with the moon eating up the clouds, and the streets were very quiet. The first sign of excitement was at the gate of the yards, where another fire-engine was just going in.

Fic slipped in beside it and took a short cut across the tracks, between and under the cars, to the other side next the big freight-house, where a fire-engine was pumping water through long lines of black hose on a big tank-car that was all in a blaze on the under side.

The tracks were flooded. Fic balanced himself on a rail and watched the blazing car with a puzzled look. Every time the stream of water fairly struck the center of the flame it flew in every direction in sheets and threads of fire, but always settled back at the bottom of the car.

The division superintendent of the road drove up. Fic knew him by sight, for he lived in Lavenham and went to his church.

“What’s the matter?” the superintendent said, in a high-keyed voice. “Why don’t you put out the fire?”

Three men drew out of the group around the fire-engine and came to the side of the buggy. One was the yardmaster, another the conductor in charge of the train, and the third the fire-chief.

“It’s naphtha,” said the chief. “There’s a leak somewhere in the pipes that lets it down to the fire a little at a time. We can’t get at it for the heat, and the water only scatters it.”

“The stuff must be pretty well out by this time,” said the conductor; “and when it gets low and the fire works up into the tank there will be an explosion. It’s awful stuff for fire.”

Fic was standing by the front wheel of the buggy and saw the superintendent’s face grow pale by the flickering light.

“Can’t you move the car?”

“We can’t get near enough to couple, and the truck is about burned through. We moved the other cars, but we can’t move the buildings.”

“Why not bring up the gravel-train from the lower switch and fill up from below until the fire is buried.”

“There won’t be time. The tank’s nearly empty now. It’s been burning all night.”

“I’m not so sure about that,” answered the chief. “Those tanks hold a lot, and it doesn’t take much naphtha to make a big blaze. What I’m afraid of is that it will explode while it is half full, and scatter the burning stuff all over the yard. Or else it will burn a week, and stop all the work in the yards while we are waiting for it to burst! That will never do.”

Fic had been doing a lot of thinking while this hasty consultation went on. He had not studied his physics for nothing, and he was sure he had the key to the problem.

“Please, Mr. Sanderson, may I speak?”

The four men looked down and saw a boy in a short jacket, with eyes that were burning with excitement, and Mr. Sanderson said, in amazement: “Hello! Who are you, and what are you doing here?”

“If you please,” said Fic, drawing himself up to the dashboard in his excitement, “I know how to put out the fire!”

“You do, do you! Well, speak up quick! It’ll be worth a good many thousand dollars and perhaps a few lives, if you do.”

“Take off the lid of the tank on top and pour water into the tank. The wind blows the fire to one side, and if you can once get a hose in you will do it.”

“How will that put the fire out?” cried the superintendent.

“It’s the specific gravity. Water is denser than naphtha and will sink to the bottom. If it doesn’t explode when you open it, it won’t afterward. The water will sink to the bottom and get into the leaky pipes.”

“I believe the lad’s right,” said the fire-chief. “At all events, we’ll try it. Who’ll help?”

Two or three volunteers came forward and lifted a ladder on the windward side of the car. The chief mounted and pried up the lid. No explosion followed, and on thrusting in his hand he found that the naphtha was still very near the top. If the fire should reach and scatter it there would be no hope of saving the buildings, he knew, and even the vapor was dangerous. He called for a hose, thrust it in at the vent, and pulled down the lid to keep the vapor in. Then he climbed down to watch the result.

Already, as he reached the ground and turned to look, the flame had diminished. In five minutes the fire was out, and water was dripping from the cooled end of the leaky pipe, which was soon tied up and made safe. Not only was the danger over, but almost the whole contents of the tank were saved.

No sooner was the work of repair over by the gleam of hastily lighted lanterns than the superintendent, like a man relieved by miracle, suddenly pulled himself up from the side of the disabled car and looked about him.

Then he shouted, “Where’s that boy?”

Nobody knew. For the moment they had forgotten all about the boy in thinking of the escape from peril; and as for John Paul, so soon as he saw that the fire was out and his faith in the principle of specific gravity vindicated, his interest had ceased, and he had turned across the flooded tracks toward home.

He slipped quietly in, got to bed by half past four without disturbing anybody, and was up as usual when his mother called him to help her with the morning work. He never troubled her with his experiments, and it did not occur to him to speak of the night’s adventure.

Even the reporter of the Daily Flashlight was too much interested in the success of the experiment to interview the boy, although he made the best of him in his story in the morning paper. He was a stranger in Lavenham, and had never heard of the uncanny doings of Gravity Gregg. It was not until the next day that the whole story got out, and Fic found it necessary to go to school by the back streets to avoid public notice.

When the division superintendent reached home in the early morning, he found his wife waiting for him with a cup of hot coffee, and as he drank it he told her the story.

“I suppose I shall have to advertise for the boy,” he said. “I can’t let him go. He saved the car and the buildings, and perhaps the lives of some of us.”

“You needn’t do that,” answered Mrs. Sanderson, who knew nothing about physics but had caught two words in the story. “He lives right around the corner in the little brown house. He’s the oldest son of the Widow Gregg, and nearly blew our Ralph’s head off one day last week with one of his experiments. All the boys call him Gravity Gregg.”

While Mrs. Gregg was at breakfast the door-bell rang, and Mr. Sanderson invited himself in. It took a long while to tell the story, for Mrs. Gregg couldn’t understand that John Paul had been anywhere but safe in bed all night, and John Paul couldn’t see that there was anything to make a fuss about in so simple an expedient in practical physics.

People said that the railroad ought to make the boy a handsome present, but it did not. What it did do was to see that he got the best kind of an education and then to put him where he could climb high in their employ.

He carries a watch which Mr. Sanderson and the fire-chief gave him as soon as he was considered by them old enough to take care of it, on the case of which is engraved a name and a date. His mother is proud of him, and, luckily for her pet ambition, she is quite as proud of another son who is just such a minister as she hoped to make of John Paul Gregg.