Tom Swift and His Air Scout; Or, Uncle Sam's Mastery of the Sky

hey seemed to come from a small building given over to electrical apparatus, and which, at the time, was not supposed to be in use. It ha

lls coming from the open door of the place. "And if it isn't Koku a

ctrical shop in a few rapid strides, and, as he entered th

g to talk to Mary. Hello there! What's going on? Is any one hurt? What's the matter?" he cried, for, at

demanded Tom,

Koku 'most dead an' no

e of Eradicate. "I done knowed yo would git into tro

though no very powerful current could be turned on in the electrical shop at

done got holt ob one ob dem air contraptions, Massa Tom, an' he cain't let go! Ha! Ha! Golly! L

with Eradicate's as they did, that it was no wonder Tom was startled. The sounds were heard in

he electric machines, designed for charging Leyden jars used in Tom's experiments, and the powerful, though not dangerous, current had so paralyzed, temporarily, the muscles of the giant's hands and ar

din' in' Massa Tom's garden right

and pulled out the switch, thus shutting off

assa Tom!" pleaded the colore

radicate was the cause of it all, he sprang at the colored man with a yell. But Eradicate did not stay to see what would happen. With a howl of terror, he raced

the giant turn away, shaking his fist at the closed door, for

pen by accident. There, it appeared, Koku had handled some of the machinery, ending by switching on the current of the machine the handles of which he later unsuspectingly picked up. Then he received a shock he

have turned on the current if he had known he could make trouble

entor. "But what is this you hinted at-a silent motor you calle

could travel along over the enemy's lines-particularly at night-and

a silent motor, or propellers that made no n

, began work in earnest on the big problem. That it was a big one Tom was not disposed to d

sked Mr. Swift, several days after t

nough for any of my flying machines, and I'm going to make them over. If I spoil them the los

n at the very foundation, and studie

ensation which is peculiar to the ear, though the vibrations caused by sound waves

"That would be an easy way of solving the problem, but I doubt if you could get the Ge

got to cut down the sound of the motor and the propeller blades, so a person, listenin

t off the reel, how to do i

sked Tom

ropellers in a vacuum,

d be a simple way out, and I'll do it, if

gree to do that

e reason all is cold and silent and still at the moon. There is no atmosphere there. Sound implies vibration. Something, such as liquid, gas, or

ium of receiving the sound waves-the ear or some part of the body. Totally deaf persons may be made aware of sound through the vibrations received through their hands or feet. They receive, of course, only

up to me to solve the problem some other way. The propellers don't really make noise enough to worry about wh

e done?"

," was Tom's

a great extent," went on Ned. "S

, "and there are more explosions to muffle. I doubt if the muffler of an auto would cut down th

les," went on Ned. "Couldn't you make a big one o

ler, or on a motor boat-a series of baffle plates arranged within a hollow cylinder. But all such de

ked later, when he and his friend talk

d following the visiting of the representatives of the Universal Flying M

ention what I was going to try to invent, and he may get ahead of me, and put a silent motor on the mar

less noise when the charges of gasoline exploded in the cylinders. It is, of course, the explosion of gasoline mixed with air that causes an

int. And, roughly, with every degree increase in the atmosphere's temperature the velocity of sound increases by one foot. Thus at a temperature of 100 degrees F

d would help him toward solving his problem of cutting down the noise. He had had some success with it, and, after days and

te was setting out some refreshments which Tom had

Damon, as he saw a series of calculations o

es about four times as fast, or nearly four thousand two hundred feet a second. You remember the rule, I suppose. 'The speed of so

om!" pleaded Ned, with a laugh. "Let that go and do some

s mounted on a testing block. "The thing isn't perfected yet, but I hope to hav

Is I gwine to help yo'

s lever, and when I say so

t giant was heah now he'd see he ain't de only one wh

ow I guess we're all ready. Can yo

Tom and Eradicate were at the testing block, on which the motor, with

the electrical switch. "All ready! Pull the starting lever, Rad, and when it's

always is when the engine of an aeroplane starts. It was as though hal

hough such was the noise that not a word could be

racket, though it was not altogether ended. Then, after a moment or two,

, and Mr. Damon, Ned, and Tom's father saw the motor fly from the testing block and shoot through the