QUEER FACTS ABOUT FALLS.

Lake Wakatip Mail, Issue 2904, 31 January 1911, Page 7

QUEER FACTS ABOUT FALLS.

WHAT THE EAST MEANS TO A GUNNER. A body dropped from a height does not fall exactly straight down. It invariably falls a little to the east of where it would fall if the earth was not rotating. Consider a ball dropped from a tall tower. The top of the tower is going faster than the bottom of the tower, for the same reason that the rim of a revolving wheel goes faster than the hub. This being the case, of course the body will fall a little in advance of the place indicated by a plumb line suspended from the place from which the ball was dropped, on account of its greater horizontal velocity, compared with the velocity of the place struck. So the error is always in the direction of motion, and as the earth always turns toward the east the body will fall to the eastward.

There are two places, however, on the surface of the earth where there will be no error, and, of course, they are where there is virtually no rotation,—at the north and south poles. Experimental trials of this phenomenon have been made by two men, Benzenburg and Freiburg. The latter used an old mine shaft for the purpose, obtaining a free fall of over five hundred feet. After over a hundred and fifty trials the mean was taken and found to be one and

j twelve hundredths inches' deviation ! to the eastward, which is very near | the proper calculated value of one j and eight-hundredths inches. Of course, the deviation differs for difI ferent places, being the maximum at j the equator and the minium at the poles. j A peculiar fact somewhat akin to j this is that a projectile in the northjem hemisphere is always deviated towards the right and in the southern hemisphere towards the left. This is occasioned by the rotation of the earth. If one sticks a hatpin through an orange and rotates the orange, it will be observed that the equator of the orange goes round faster than any other part, the Velocity of the different parts decreasing as the approach is made to | the poles. I Now consider the earth in like ■ manner. Suppose someone at the | equator fired directly at the north j pole along the Surface of the ground, jAs the cannon is moving at the i equator faster than any other thing lis moving, the ball will have this velocity to the east given to it. It is aimed, however, at a place going much slower. Therefore, the ball will hit a good distance to the right of the object aimed at. If the shot is fired towards the equator, it will fall behind the object aimed at; for the things on the equator are getting out of the way, as it were faster than the cannon that shot the ball. But the deviation will still be to the right from the cannoneer's view-point. This deviation is not so small as might be imagined. Cannon have been made to shoot ten miles. An object at the equator goes approximately one thousand miles an hour, an object at the north pole zero miles an hour, As it is about six thousand miles from the equator to the pole, ' a body ten miles from the equator 1 would go about nine hundred and , ninety-eight miles an hour. From 1 this can be calculated the difference j in feet to the second. It is found to j be three. So, if it took the ball only j one second to go that ten miles, it I would hit three feet too far to the ! right. If it took it thirty-five j seconds (which is about the correct ' figure), it would hit one hundred and j five feet too far to the right. This is one reason why in naval warfare ships shooting at one an-' other from great distances should get in an east and west line if they cannot get the correction due to this rotation of the earth. Of course the only thing necessary to be 1 known is the latitude of the place, which is taken daily on all ships on cruise.—"Popular Science Sittings."