WARNINGS
For a moment or two Tom Swift did not seem to comprehend what Ned had said.He remained staring, first at his chum, who stood pointing, and from him Tom's gaze wandered to the top of the door.It may have been, and probably was, that Tom was thinking of other matters at that instant.But Ned said again:
"Wouldn't that do, Tom? Check the recoil of the gun with whatever stuff is in that arrangement!"A sudden change came over Tom's face.It was lighted up with a gleam of understanding.
"By Jove, Ned, old man!" he cried."I believe you've struck it! And to think that has been under my nose, or, rather, over my head, all this while, and I never thought of it.Hurray! That will solve the problem!""Do you think it will?" asked Ned, glad that he had contributed something, if only an idea, to Tom's aerial warship.
"I'm almost sure it will.I'll give it a trial right away.""What's in that door-check?" Ned asked."I never stopped before to think what useful things they are, though at the bank, with the big, heavy doors, they are mighty useful.""They are a combination of springs and hydrostatic valves," began Tom.
"Good-night!" laughed Ned."Excuse the slang, Tom, but what in the world is a hydrostatic valve?""A valve through which liquids pass.In this door-check there may be a mixture of water, alcohol and glycerine, the alcohol to prevent freezing in cold weather, and the glycerine to give body to the mixture so it will not flow through the valves too freely.""And do you think you can put something like that on your guns, so the recoil will be taken up?" Ned wanted to know.
"I think so," spoke Tom."I'm going to work on it right away, and we'll soon see how it will turn out It's mighty lucky you thought of that, for Isure was up against it, as the boys say.""It just seemed to come to me," spoke Ned, "seeing how easily the door closed.""If the thing works I'll give you due credit for it," promised Tom."Now, I've got to figure out how much force a modified hydrostatic valve check like that will take up, and how much recoil my biggest gun will have.""Then you're going to put several guns on the Mars?" asked Ned.
"Yes, four quick-firers, at least, two on each side, and heavier guns at the bow and stern, to throw explosive shells in a horizontal or upward direction.For a downward direction we won't need any guns, we can simply drop the bombs, or shells, from a release clutch.""Drop them on other air craft?" Ned wanted to know.
"Well, if it's necessary, yes.Though I guess there won't be much chance of doing that to a rival aeroplane or dirigible.But in flying over cities or forts, explosive bombs can be dropped very nicely.For use in attacking other air craft I am going to depend on my lateral fire, from the guns mounted on either beam, and in the bow and stern.""You speak as though you, yourself, were going into a battle of the air," said Ned.
"No, I don't believe I'll go that far," Tom replied."Though, if the government wants my craft, I may have to go aloft and fire shots at targets for them to show them how things work.
"Please don't think that I am in favor of war, Ned," went on Tom earnestly."I hate it, and I wish the time would come when all nations would disarm.But if the other countries are laying themselves out to have aerial battleships, it is time the United States did also.We must not be left behind, especially in view of what is taking place in Europe.""I suppose that's right," agreed Ned."Have you any of your guns ready?""Yes, all but the mounting of them on the supports aboard the Mars.I haven't dared do that yet, and fire them, until I provided some means of taking up the recoil.Now I'm going to get right to work on that problem."There was considerable detailed figuring and computation work aheadof Tom Swift, and I will not weary you by going into the details of higher mathematics.Even Ned lost interest after the start of the problem, though he was interested when Tom took down the door-check and began measuring the amount of force it would take up, computing it on scales and spring balances.
Once this had been done, and Tom had figured just how much force could be expected to be taken up by a larger check, with stronger hydrostatic valves, the young inventor explained:
"And now to see how much recoil force my guns develop!" "Are you really going to fire the guns?" asked Ned.
"Surely," answered Tom."That's the only way to get at real results.I'll have the guns taken out and mounted in a big field.Then we'll fire them, and measure the recoil.""Well, that may be some fun," spoke Ned, with a grin."More fun than all these figures," and he looked at the mass of details on Tom's desk.
This was the second or third day after the fire in the red shed, and in the interim Tom had been busy making computations.These were about finished.Meanwhile further investigation bad been made of clues leading to the origin of the blaze in the shed, but nothing had been learned.
A photo-telephone had been installed near Eradicate's quarters, in the hope that the mysterious stranger might keep his promise, and come to see about the mule.In that case something would have been learned about him.But, as Tom feared, the man did not appear.
Ned was much interested in the guns, and, a little later, he helped Tom and Koku mount them in a vacant lot.The giant's strength came in handy in handling the big parts.
Mr.Swift strolled past, as the guns were being mounted for the preliminary test, and inquired what his son was doing"It will never work, Tom, never!" declared the aged inventor, when informed."You can't take up those guns in your air craft, and fire them with any degree of safety.""You wait, Dad," laughed Tom."You haven't yet seen how the Newton hydrostatic recoil operates."Ned smiled with pleasure at this.
