far the greater portion of the hemisphere in sight was covered with innumerable volcanic mountains, conical in shape, and having more the appearance of artificial than of natural protuberance. The highest among them does not exceed three and three-quarter miles in perpendicular elevation; but a map of the volcanic districts of the Campi Phlegraei would afford to your Excellencies a better idea of their general surface than any unworthy description I might think proper to attempt. The greater part of them were in a state of evident eruption, and gave me fearfully to understand their fury and their power, by the repeated thunders of the miscalled meteoric stones, which now rushed upward by the balloon with a frequency more and more appalling.
"April 18th. To-day I found an enormous increase in the moon's apparent bulk -- and the evidently accelerated velocity of my descent began to fill me with alarm. It will be remembered, that, in the earliest stage of my speculations upon the possibility of a passage to the moon, the existence, in its vicinity, of an atmosphere, dense in proportion to the bulk of the planet, had entered largely into my calculations; this too in spite of many theories to the contrary, and, it may be added, in spite of a general disbelief in the existence of any lunar atmosphere at all. But, in addition to what I have already urged in regard to Encke's comet and the zodiacal light, I had been strengthened in my opinion by certain observations of Mr. Schroeter, of Lilienthal. He observed the moon when two days and a half old, in the evening soon after sunset, before the dark part was visible, and continued to watch it until it became visible. The two cusps appeared tapering in a very sharp faint prolongation, each exhibiting its farthest extremity faintly illuminated by the solar rays, before any part of the dark hemisphere was visible. Soon afterward, the whole dark limb became illuminated. This prolongation of the cusps beyond the semicircle, I thought, must have arisen from the refraction of the sun's rays by the moon's atmosphere. I computed, also, the height of the atmosphere (which could refract light enough into its dark hemisphere to produce a twilight more luminous than the light reflected from the earth when the moon is about 32 degrees from the new) to be 1,356 Paris feet; in this view, I supposed the greatest height capable of refracting the solar ray, to be 5,376 feet. My ideas on this topic had also received
confirmation by a passage in the eighty-second volume of the Philosophical Transactions, in which it is stated that at an occultation of Jupiter's satellites, the third disappeared after having been about 1" or 2" of time indistinct, and the fourth became indiscernible near the limb.{*4}
"Cassini frequently observed Saturn, Jupiter, and the fixed stars, when approaching the moon to occultation, to have their circular figure changed into an oval one; and, in other occultations, he found no alteration of figure at all. Hence it might be supposed, that at some times and not at others, there is a dense matter encompassing the moon wherein the rays of the stars are refracted.
"Upon the resistance or, more properly, upon the support of an atmosphere, existing in the state of density imagined, I had, of course, entirely depended for the safety of my ultimate descent. Should I then, after all, prove to have been mistaken, I had in consequence nothing better to expect, as a finale to my adventure, than being dashed into atoms against the rugged surface of the satellite. And, indeed, I had now every reason to be terrified. My distance from the moon was comparatively trifling, while the labor required by the condenser was diminished not at all, and I could discover no indication whatever of a decreasing rarity in the air.
"April 19th. This morning, to my great joy, about nine o'clock, the surface of the moon being frightfully near, and my apprehensions excited to the utmost, the pump of my condenser
"April 18th. To-day I found an enormous increase in the moon's apparent bulk -- and the evidently accelerated velocity of my descent began to fill me with alarm. It will be remembered, that, in the earliest stage of my speculations upon the possibility of a passage to the moon, the existence, in its vicinity, of an atmosphere, dense in proportion to the bulk of the planet, had entered largely into my calculations; this too in spite of many theories to the contrary, and, it may be added, in spite of a general disbelief in the existence of any lunar atmosphere at all. But, in addition to what I have already urged in regard to Encke's comet and the zodiacal light, I had been strengthened in my opinion by certain observations of Mr. Schroeter, of Lilienthal. He observed the moon when two days and a half old, in the evening soon after sunset, before the dark part was visible, and continued to watch it until it became visible. The two cusps appeared tapering in a very sharp faint prolongation, each exhibiting its farthest extremity faintly illuminated by the solar rays, before any part of the dark hemisphere was visible. Soon afterward, the whole dark limb became illuminated. This prolongation of the cusps beyond the semicircle, I thought, must have arisen from the refraction of the sun's rays by the moon's atmosphere. I computed, also, the height of the atmosphere (which could refract light enough into its dark hemisphere to produce a twilight more luminous than the light reflected from the earth when the moon is about 32 degrees from the new) to be 1,356 Paris feet; in this view, I supposed the greatest height capable of refracting the solar ray, to be 5,376 feet. My ideas on this topic had also received
confirmation by a passage in the eighty-second volume of the Philosophical Transactions, in which it is stated that at an occultation of Jupiter's satellites, the third disappeared after having been about 1" or 2" of time indistinct, and the fourth became indiscernible near the limb.{*4}
"Cassini frequently observed Saturn, Jupiter, and the fixed stars, when approaching the moon to occultation, to have their circular figure changed into an oval one; and, in other occultations, he found no alteration of figure at all. Hence it might be supposed, that at some times and not at others, there is a dense matter encompassing the moon wherein the rays of the stars are refracted.
"Upon the resistance or, more properly, upon the support of an atmosphere, existing in the state of density imagined, I had, of course, entirely depended for the safety of my ultimate descent. Should I then, after all, prove to have been mistaken, I had in consequence nothing better to expect, as a finale to my adventure, than being dashed into atoms against the rugged surface of the satellite. And, indeed, I had now every reason to be terrified. My distance from the moon was comparatively trifling, while the labor required by the condenser was diminished not at all, and I could discover no indication whatever of a decreasing rarity in the air.
"April 19th. This morning, to my great joy, about nine o'clock, the surface of the moon being frightfully near, and my apprehensions excited to the utmost, the pump of my condenser
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