distance is, therefore, the one that should give us the basis of all
calculations.

"Regarding question No. 3, 'What would be the duration of the
projectile's transit to which a sufficient initial speed has been given,
and consequently at what moment should it be hurled so as to reach the
moon at a particular point?'

"If the projectile kept indefinitely the initial speed of 12,000 yards a
second, it would only take about nine hours to reach its destination;
but as that initial velocity will go on decreasing, it will happen,
everything calculated upon, that the projectile will take 300,000
seconds, or 83 hours and 20 minutes, to reach the point where the
terrestrial and lunar gravitations are equal, and from that point it
will fall upon the moon in 50,000 seconds, or 13 hours, 53 minutes, and
20 seconds. It must, therefore, be hurled 97 hours, 13 minutes, and 20
seconds before the arrival of the moon at the point aimed at.

"Regarding question No. 4, 'At what moment would the moon present the
most favourable position for being reached by the projectile?'

"According to what has been said above the epoch of the moon's perigee
must first be chosen, and at the moment when she will be crossing her
zenith, which will still further diminish the entire distance by a
length equal to the terrestrial radius--i.e., 3,919 miles; consequently,
the passage to be accomplished will be 214,976 miles. But the moon is
not always at her zenith when she reaches her perigee, which is once a
month. She is only under the two conditions simultaneously at long
intervals of time. This coincidence of perigee and zenith must be waited
for. It happens fortunately that on December 4th of next year the moon