"Regarding question No. 5, 'At what point in the heavens ought the cannon destined to hurl the projectile be aimed?'
"The preceding observations being admitted, the cannon ought to be aimed at the zenith of the place (the zenith is the spot situated vertically above the head of a spectator), so that its range will be perpendicular to the plane of the horizon, and the projectile will pass the soonest beyond the range of terrestrial gravitation. But for the moon to reach the zenith of a place that place must not exceed in latitude the declination of the luminary—in other words, it must be comprised between 0° and 28° of north or south latitude. In any other place the range must necessarily be oblique, which would seriously affect the success of the experiment.
"Regarding question No. 6, 'What place will the moon occupy In the heavens at the moment of the projectile's departure?'
"At the moment when the projectile is hurled into space, the moon, which travels forward 13° 10' 35" each day, will be four times as distant from her zenith point—i.e., by 52° 42' 20", a space which corresponds to the distance she will travel during the transit of the projectile. But as the deviation which the rotatory movement of the earth will impart to the shock must also be taken into account, and as the projectile cannot reach the moon until after a deviation equal to sixteen radii of the earth, which, calculated upon the moon's orbit, is equal to about 11°, it is necessary to add these 11° to those caused by the already-mentioned delay of the moon, or, in round numbers, 64°. Thus, at the moment of firing, the visual radius applied to the moon will describe with the vertical line of the place an angle of 64°.
"Such are the answers to the questions proposed to the Observatory of
Cambridge by the members of the Gun Club.
"To sum up—
"1st. The cannon must be placed in a country situated between 0° and 28° of north or south latitude.
"2nd. It must be aimed at the zenith of the place.
"3rd. The projectile must have an initial speed of 12,000 yards a second.
"4th. It must be hurled on December 1st of next year, at 10hrs. 46mins. 40secs. p.m.