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UNITED STATES JAPAN EXPEDITION.
OBSERVATIONS
THE ZODIACAL LIGHT,
APRIL 2, 1853, TO APRIL 22, 1855,
MADE CHIEFLY ON BOARD
THE UNITED STATES STEAM-FRIGATE MISSISSIPPI,
DURING HER LATE CRUISE IN EASTEEN SEAS, AND HER VOYAGE HOMEWARD :
WITH
CONCLUSIONS FROM THE DATA THUS OBTAINED;
^^H BY
REV. GEORGE JONES, A. M.,
CHAPLAIN UNITED STATES NAVY.
"Je ne comprends pita par quel sort tin olijet [la Lumitre Zodiaeale], qui tomlte de si pres F astronomic moderne et la jilii/sigue c£leste, a
(t( nfgligi jusqu' a ce paint par lex astronomes et par les auteurs mf/eoroloyiques." — MAIEAN.
VOLUME III.
WASHINGTON:
BEVERLKY TUCKER, SENATE PRINTER.
1856.
IN SENATE OF THE UNITED STATES,
January 22, 1855.
Ordered to be printed, and that 5, 000 additional copies be printed ; five hundred of which for the use of Commodore
Perry.
January 29, 1855.
Ordered, that 500 copies be for the use of the Navy Department.
INTRODUCTION.
APPEARANCE OF THE ZODIACAL LIGHT.
To PERSONS not familiar with the subject of this work, it may be proper to state, that, what
is called the Zodiacal Light, is a brightness which appears in the western sky after sunset, and
before sunrise in the east, following nearly or quite the line of the ecliptic in the heavens, and
stretching upwards to various elevations, according to the seasons of the year. It has been
called by this name, from the fact that it was formerly thought to confine itself within the limits
of the zodiac. It appears to best advantage when the ecliptic makes its highest angle with the
spectator's horizon; at which times, in moderate latitudes, it reaches to his zenith or beyond it,
having near the horizon a striking brilliancy, and thence fading upward, mostly by impercep-
tible degrees, till, at its vertex, it can be made out only by a careful and experienced eye. As
those seasons advance when the ecliptic is declining gradually towards the horizon, the Zodi-
acal Light fades away, till it is perhaps entirely lost, or can be seen only by those who have
followed it, in its changes, night after night, and are thus able, by familiar acquaintance, to
detect and trace its dim markings on the sky.
In our high northern latitudes, it can be seen with difficulty, or at least can be made out
unsatisfactorily, through a large portion of the year ; while at the European observatories,
most of them still further north, it is generally very obscure; and observers in these countries
have, therefore, been discouraged from attention to a subject for which their circumstances are
so little favorable. In the lower latitudes, however, and especially in those near the equator,
it lias often an exceeding brilliancy at the horizon, ascending from this, a striking object, far
into the sky; and I have in several instances known ike reveille to be beaten in our ships, evi-
dently from mistaking the Zodiacal Light for the dawn. I remember, on one occasion, when in
the " Mississippi " during her late cruise, we had sighted the light-house of Point du G-alle, in
Ceylon, in the evening, and the ship was ordered to be kept lying off till the morning would
permit us to enter the harbor, word was passed for the "officer of the deck to send for the
captain and first lieutenant at early dawn." I was on deck in the morning at my observa-
tions, a few minutes after four o'clock, when the lieutenant on duty came up to me and said :
"Don't you call this early day-light?" I answered "No, it is not day-light yet." "Why,"
he said, "what do you call this over here?" pointing to the Zodiacal Light, which was show-
ing itself with an effulgence that might very easily lead to such a mistake; though it wanted
yet more than half an hour of the earliest dawn. See also the close of my record No. Ill,
where it is noted that, at two hours after sun-set, I overheard one of the quartermasters, as he
was looking at the Zodiacal Light in the west, remark to another: "If that was not in the
wiong part of the sky, I should say that the sun was just going to rise there!" Humboldt, in
IV INTRODUCTION.
Cosmos, vol. 1, remarks on this subject : "Those who have lived for many years in the zone of
palms, must retain a pleasing impression of the mild radiance with which the Zodiacal Light,
shooting pyramiclically upwards, illumines a part of the uniform length of tropical nights. I
have seen it shine with an intensity of light equal to the Milky Way in Sagittarius ; and that,
not only in the rare and dry atmosphere of the summits of the Andes, at an elevation of from
thirteen to fifteen thousand feet, but even on the boundless grassy plains, the llanos of Vene-
zuela, and on the sea-shore beneath the ever clear sky of Cuniana. This phenomenon was
often rendered especially beautiful by the passage of light fleecy clouds, which stood out in bold
relief from the luminous back-ground."
It may be well to remark here, however, that the Zodiacal Light has a warm, yellowish tint,
unlike the cold, white light of the Milky Way.
HISTORY OF OBSERVATIONS PREVIOUS TO THESE.
It seems scarcely probable that a phenomenon, so striking in southern latitudes, could have
escaped the attention of early astronomers in those countries; but we meet with nothing in
their works of a fully definite and reliable character. We are not to infer, however, from this,
that the Zodiacal Light did not exist and shine then, as it does in modern times. Seafaring
men have to be ceaseless watchers of the nightly skies ; yet it is very seldom that one can be
found who has ever noticed this phenomenon as such, unless his attention has been directed to
it in a particular manner, or from some particular circumstance. Its most striking aspects are
just before the dawn, or just after twilight, at which time it forces itself on the attention, but
is in general supposed to be a part of the crepuscule itself. What I have just said about the mis-
takes in our squadron is to the point ; and such facts will also explain the doubts that arose in
Cassini's mind, when, in 1683, he first began to notice the Zodiacal Light. He had been pre-
viously employed in careful observations of other matters in the same quarter of the heavens,
without having at all noticed this phenomenon ; whence he half inferred that it now, for the
first time, made its appearance in the sky — an inference which subsequent observations and
reading led him readily to abandon.
Kecurring to our theme of the ancient records, it has been thought that Pliny alludes to it
under the name of trabes, or the doxou^ of the Greeks, which Hurnboldt, however, supposes to
refer to another matter.
Festus Pompeius notices something of this character, under the terms Acies and Cyparissee.
Ammonius, in his life of Charlemagne, A. D. 807, mentions an appearance somewhat like that
of the Zodiacal Light; but nothing fully reliable can be found till we come to Childrey's Bri-
tannia Baconica* published in 1G61, in which is a clear statement of his having seen it, together
with a brief description of its appearance and shape, occupying, however, but a few lines of his
book.
The next observer, and one to whose merit all subsequent writers on this subject have deferred,
was Dominions Cassini, an Italian by birth, but, at the time of his observations, attached to
" "There is another thing which I recommend to the observation of mathematical men, which is : that in February, and
for a little before and a little after that month (as I have observed several years together), about six in the evening, when
the twilight hath almost deserted the horizon, you shall see a plainly discernible way to the twilight, striking up towards
the Pleiades, and seeming almost to touch them. It is so observed any clear night, but it is best iliac noctf. There is no
such way to be observed at any other time of the year (that I can perceive), nor any other way at that time to be perceived
darting up elsewhere. And I believe it hath been, and will be constantly visible at that time of the year. But what the
cause of it in nature should be, I cannot yet imagine, but leave it to future inquiry. — Britannia Baconica, 1661, p. 183.
INTRODUCTION. V
the Royal Observatory at Paris, and doubtless the greatest cosmologist of his day. His first
notice of the Zodiacal Light was on the evening of the 18th of March, 1083, when, observing
in the west for other things, he was struck with this luminous streak reaching far up in the
sky. Unfortunately for subsequent times, Cassini's active mind immediately began to theorize;
and he had made but ten observations, when he worked up an hypothesis, which, though formed
so rapidly and on such slender and insufficient data, has yet, ever since, warped the judgment
of astronomers, and even led to imperfect modes of observing the phenomena of the Zodiacal
Light. We have, in this case, an exhibition of the danger of beginning to theorize before we
have a sufficient supply of data to work upon.
Cassini discovered very soon that, as time advanced through March and April, the upper or
northern edge of this Light inclined more and more off from the ecliptic, and stretched on
farther to the northward; and knowing that the sun's equator, as shown by his spots, was also
now stretching off from the ecliptic in a similar way, he came to the conclusion that the sub-
stance giving this light was closely connected with the sun's equator, and was consequently
changing its position with that equator*. He argued further, that, as the sun has an atmo-
CASSINI'S DIAGRAM.
° " Je fis reflexion que 1'e'quinoxial propre du soleil, qui est counu par le mouvement de ses taches qui se meuvent autour
de lui, dgcliaait alors [March and April] de l'e"cliptique selon apparence du cote" d'orient vers septentrion, et que cette de-
clinaison augmentait de Mars en Avril ; ce que me fit pen&er que le mouvement apparant de cette lumiere pourrait etre regie"
par celui du soleil autour de son axe, et la lumiere renvoye'e a peu pres selon le plan de son e'quinoxial. " — Mfmoires de
I' Academic Royale dcs Sciences, tome viii,p. 127.
VI INTRODUCTION.
sphere, and is, therefore, capable of emitting dense vapors, and, moreover, is continually sending
out matter of exceeding fineness, which we call light; consequently, this luminary might also,
by its motion on its axis, send out a substance intermediate in character between the two, which
substance, either self-luminous, or by reflection, might give us the Zodiacal Light. The dia-
gram which is attached to his article on this subject in the Memoires de I'Acadcmie Boyale des
Sciences, vol. 8, gives the shape of this body or emanation, as lenticular, with its greatest
thickness about twice that of the sun as seen in March, but only of the sun's thickness when
seen by us in June ; at which latter time, also, it is drawn so as not to reach the horizon of a
spectator in the latitude of Paris. Whether he meant to have this lenticular-shaped medium to
be considered as attached to the sun, and revolving at the same time with it, or not, is not appa-
rent from his writings. At one time he appeared to think that this matter might consist of an
infinite number of small stars, such as are thought to give us the light of the Milky Way, and
he made telescopic observations with reference to such an idea; but the results were not satis-
factory to his mind. So, also, with scintillations or bright dartings of brief light along the
course of the Zodiacal Light, which for a while were thought to be seen; further observations
made these doubtful, and the idea of such appearances was laid aside.
I have dwelt so long upon Cassini's observations and theories, inasmuch as these obser-
vations, though made one hundred and seventy years ago, exceed in amount all others
subsequently printed ; and his annotations have a distinctness which I have not been able to
find in any other work ; besides that his theory has had such an important influence
over the minds of astronomers in all subsequent times. He continued his observations,
pretty regularly, for six years; and afterwards in a more desultory manner, till 1693; and
thus we have eleven years of very important records from his pen. I have, from his detailed
descriptions, been able to draw outlines on my star-charts for eleven nights, when his lati-
tudes and my own were sufficiently near for comparison of results ; and I find that, in many
instances the boundaries of the Zodiacal Light, at his time (one hundred and seventy years
ago), were almost, or perhaps quite, the same as at present. It is somewhat difficult to get his
boundaries precisely, inasmuch as he describes them by the figures of the pictured constellations ;
which pictures, we know, are often varied to suit the fancy of the artist dealing with the stars,
and are therefore no certain guide. Some of these outlines from his records, drawn out on
charts, are appended to this work (Nos. 342-351) for comparison with those of our own
times.
Cassini's labors gave a start to other observers, among whom the most eminent was Fatio de
Duillier, for a while his colleague at Paris, but afterwards residing near Geneva, where he
made observations; of which, however, we have only a few records in Cassini's own work.
Fatio de Duillier, however, is worthy of particular notice, as having, instead of Cassini's idea
of reflecting particles originating in the sun, conceived that of particles of matter distinct from
the sun, and arranged in shape like a "solid zodiac;" which body of uneven surfaces, and rota-
ting around the sun, he supposed to give us the Zodiacal Light.* Observations were also made
by Kirch and Eimmart, in Germany, from 1688 to 1694, and were published, but only a few of
them in detail.
" II pi. Fatio de Duillier] me communiqna [7 October, 168-1] I'bypntliese qu'il avait coneiie six on sept innis aupar.i-
vnnt. Elle a cela de comun avec ce quej'avais propose" dans le Journal du 1C83, qu'il suppose dans IVUu-r des particulcs
capaliles de dcjtuurner et de re'fleehir Inminv. II Irs dispnsa hint aiitour dn soldi cmnme dans un zodiaque solide, large, et
inv.nnlicr, cmnpris entre deux surfaces oourbes et ondoyantcs, en sortr qn'elles pnissenl comprcndiv dans un nioindre espace
les oH'itcs 'li's [ilauetcs de'crites autour du snk-il, placces a divcrscs distances et iiieliiu'es diverseinent 1'une vors 1'autre. Le
INTRODUCTION. VII
Cassini had requested travellers in southern latitudes to give attention to the subject; and in
1684, Noel, a Jesuit priest in the East Indies, when near the equator, saw this Light so bril-
liantly exhibited, that he thought of giving it the name of the Second Crepuscule.
In 1687, M. de la Loubere, French envoy to Siam, saw it repeatedly; and in 1690, it was
noticed at Pondichery ; but the accounts we have from all these observers are little more than
a simple notice that it was seen.
In 1*731, Mairan, in his important work on the Aurora Borealis, took notice of the Zodiacal
Light, to which he had given considerable attention ; but his work affords us very little of a
tangible and reliable character. He is remarkable for a theory that the Zodiacal Light is
reflected from the sun's atmosphere, stretched out into a flattened spheroid, or lenticular-shaped
body, revolving -with the sun ; an idea which La Place has forever set at rest, by demonstrating
that the sun's atmosphere "can extend no further than to the orbit of a planet, whose periodi-
cal revolution is performed in the same time as the sun's rotary motion about its axis, or in
twenty-five days and a half; that is, only as far as -fy of Mercury's distance from the sun."
From the time of Mairan little seems to have been done on this subject, and we are scarcely
furnished with a notice of it, until in 1796, the publication of the Systeme du Monde, in note
7 appended to it, gave the world La Place's nebular theory, and with it also a theory
respecting the substance producing the Zodiacal Light. This great writer says: "If in the
zones abandoned by the atmosphere of the sun, there are any molecules too volatile to be united
to each other, or to the planets, they ought, in continuing to circulate around this star, to
offer all the appearances of the Zodiacal Light, without opposing any sensible resistance to the
different bodies of the planetary system, either ou account of their extreme rarity, or because
their motion is nearly the same as that of the planets with which they come in contact. "-
Exposition du Systeme du Monde, note 7, p. 471.
It will be observed that all the theories and all the reasonings on the Zodiacal Light, which
we have in these various authors, seem to have been founded on Cassini' s conclusion, that the
axis of this light has a relation to the sun's equator, rising and sinking with it; which con-
clusion was drawn after only ten observations — the first detailed observations ever made. It is
to be regretted that, in the one hundred and seventy years since his time, we have been fur-
nished with so small an amount of facts instead of theories. My own observations, I believe,
are the first, of any detailed character, ever carried into latitudes south of the equator, or even
into regions about the equatorial line.
When the French corvette La JBonite, was about to start on her voyage of circumnavigation,
in 1836, a special committee was appointed by the French Academy of Sciences to draw up
instructions for scientific observations on board; and Arago was deputed by them to select
matters connected with the physique of the globe. In his paper he enjoins particular attention
to the Zodiacal Light ; but even these very instructions themselves show how blindly the scientific
world were then groping their way in a matter where facts only could give reliable evidence.
He ends with saying, "Our young compatriots can, therefore, give themselves up zealously to
the observations which we here designate. The question is important, and no one can yet
flatter himself that he has given it a definite solution."
milieu de 1'e'paisseur qu'ellcs enferment est marque'e par une surface pareilletueiit courlie et ondoyante, qui passe par les
orbites de toutes les planetes et determine le milieu de la lumiere. Les particules qui la renvoyent sont comprises dans
1'orbe annuel au temps qu'elle parait. II leur donne un mouvement par lequel elles vont ou sont porte'es autour du soleil
par des cercles eiitiers, avec la meme force que les planetos m£mes." — Mem. de VAcad. Ray. da Sci., tome viii. p. 158.
VIII INTRODUCTION.
The subject appears, however, to have been entirely neglected by the officers and savans of
La Bonite.
Soon after the wonderful meteor-shower of 1833, the subject of the Zodiacal Light was
revived ; and observations were made connected with the query, whether that extraordinary
display of meteors was not owing to the passage of our earth, and its atmosphere, through the
substance aifording that Light. Our own eminent countryman, Professor Olmsted, with other
gentlemen, at different observatories, were diligent observers, and with various results; going
little, however, beyond the question of the meteoric shower and its cause. Biot, in France,
came out as an advocate of this theory, and attempted to show that the shower was owing to
the earth's passing, at that time, near the node of the Zodiacal Light. This led J. C. Houzeau
to calculations, in order to see whether the nodes of the Zodiacal Light and sun do actually cor-
respond ; and, in the AstronomiscJie Nacliriclden of 1844 he has published the result of his
examinations of fifty-eight observations on this Light, by nine of the most diligent observers,
including Mr. Herrick, of Yale College, whose industry on this subject has never been excelled
by any one. Houzeau thinks that, from these examinations, he has shown that these nodes are
different; and that therefore "the supposition of the existence of this Light in the plane of the
sun's equator does not satisfy the observations made." The closing sentence of his very inter-
esting article gives the first intimation, and the only one that I have met with, that the Zodia-
cal Light has a near connexion with our own globe; and I will quote it at length. He says:
"One is struck, without doubt, with the near approach which our elements show between the
line of nodes of the Zodiacal Light, and that of the nodes of the terrestrial equator upon the
ecliptic. This circumstance, as far as it is verified, may cast a new day upon the causes of this
luminous phenomenon — causes which are, it may be, more local than have been hitherto
supposed."
During the next year (i. e. in 1845), there was published in Comptes Rendus (vol. 16, pp.
687-8,) a letter from Mon. Ad. Matthiesson to Arago, detailing some experiments made at
Paris, to ascertain whether there was heat connected with the Zodiacal Light. I give his
remarks for whatever they may be considered worth. He says: "Monday, 27th March, at eight
in the evening, a concave mirror, of one metre in diameter, highly polished, with a thermome-
ter in air, very sensitive to heat, did not indicate any elevation of temperature. An elevation,
however, was perceptible when the axis of the mirror was directed to the Zodiacal Light.
"The next evening I placed an excellent thermo-electric pile of Mr. Ruhmkopf, of twenty-
five pairs, in a spot slightly hollowed out, between the Arc de I'Etoile and the Bois de Boulogne.
The needle of the galvanometre rested at zero, when the pile, fortified with its cone condenser,
was turned upon the polar star. Turned towards the tail of the comet above Orion, it remained
at zero; towards the nucleus, the needle indicated two degrees. But the impression of heat
gradiially increased when the pile was turned towards the Zodiacal Light, after passing the tail
of the cornet: towards the Pleiades, 10° of deviation; towards the base of the Zodiacal Light,
12° ; above the point where the sun had set, 5°. At 9 o'clock, the same result for the comet;
towards the Pleiades, 8° ; towards the base of the Zodiacal Light, 12° ; above the point where
the sun had set, 3°. At 9h 30m, 7°, 10°, 2°, and the same result for the comet,"
He thinks it, however, doubtful whether the increased temperature indicated when turned
towards the Zodiacal Light, was owing to the substance giving that light itself, or to heat left
in that portion of our atmosphere by the sun lately set.
INTRODUCTION. U
In 1848, Professor G. Piazzi Smyth read before the Royal Society of Edinburgh a valuable
paper giving account of observations made by him in South Africa some years previously, and
also of an instrument invented by him for getting the position of the apex of the Zodiacal
Light. To his paper (published in the Transactions of the Society, vol. xx, part iii) is appended
an interesting exhibition of this phenomenon, as seen at the Cape of Good Hope in July, 1845.
There is only one subject more to be noticed in this history of observations on the Zodiacal
Light. At the twenty-second meeting of the British Association for the Advancement of
Knowledge (in 1852),- a paper was read from the Kew Observatory, giving account of observa-
tions from January to April, 1850, by Mr. H. R. Birt. It has little in detail, and gives a
statement, which is of little value, of the changes of inclination of the axis of the Zodiacal
Light towards the ecliptic; but there occurs, moreover, the following passage in the records of
the earlier part of March: " One evening, there was a sudden brightening of the light for an
instant, and also variations in its lustre of an intermittent character. These intermissions of
brightness were observed on the same evening by Mr. Lowe, of Nottingham. They are
described by the author not to be of the nature of pulsations, in the usual acceptation of the
term, but to consist of alternate brightenings and dimniiugs of the entire mass of light, such as
might be produced by the approach and recess of a luminous body." (Am. Jour. ScL, xv,
new series, page 121.)
Baron Humboldt also noticed similar appearances, as we learn from the following passage in
his published works: "I have occasionally been astonished, in the tropical climates of South
America, to observe the variable intensity of the Zodiacal Light. As I passed the nights,
during many months, in the open air, on the shores of rivers and on llanos, I enjoyed ample
opportunities of carefully examining this phenomenon. When the Zodiacal Light had been
most intense, I have observed that it would be perceptibly weakened for a few minutes, until it
again suddenly shone forth in full brilliancy," &c. (See Cosmos, vol. i.)
In our own country, some attention has been paid to the Zodiacal Light by individuals here
and there ; and our astronomers have been earnestly desirous of facts, on which to ground
opinions ; but without being able themselves to accumulate any extensive data, on account of
the high northern aspect of our skies, and the low angle at which the ecliptic ranges with their
horizon through much of the year.
MY OWN OBSERVATIONS AND THEIR RESULTS.
The historical items just given have been collected from various authorities since my return
to the United States ; for, previous to sailing on this cruise, I had given the Zodiacal Light no
attention, more than to be aware that there was such a thing ; and I had never seen it to know
it as such.
I hope the reader will now pardon a little egotism in these remarks ; for it is proper that ho
should know the circumstances of my observations, and thus be able to form his own opinion
about their reliability and the results. While I was busy with preparations for the cruise, my
friend, Professor Dana, of Yale College, suggested to me that I would have good opportunities
for observations on the Zodiacal Light; but my mind was then fully occupied with other
matters, and I could not have found time for resorting to libraries, or for making other prepa-
rations, if, indeed, I had known how they were to be made. Fortunately, at my last visit to
my old home at the Naval Academy in Annapolis, off which our frigate was then lying, I pro-
I INTRODUCTION.
cured from that institution a nine-inch celestial globe ; and this, with an odd number of the
American Journal of Science, containing some remarks by Professor Olmsted on the Zodiacal
Light, and two of Nichols's works on Astronomy, were my only helps. The globe, published by
the "Society for the Diffusion of Useful Knowledge" in England, proved, however, to be of
uncommon accuracy throughout.
This very lack of the means of information, however, bad its advantages ; for I was thus kept
from being drawn into the vortex of former opinions, or of being borne down by the influence of
great names ; and when, by and by, I became deeply interested in this- subject, I was left to
pursue my observations all the more carefully, and with the greater jealousy of mistake, from
the fact that I had nothing to depend on but myself. Thus the data in this book are inde-
pendent of all preconceived opinions, and I may add, also, in a great measure, of any opinions
by myself; for I determined, in the first place, to get facts; and when I saw how frequently
the dimness and indefiniteness of the Zodiacal Light would admit of self-deception, even where
the intentions might be the most honest, I became jealous of myself to such a degree as not to
allow myself, except in very rare cases, to refer back, or to compare present observations with
those of any previous date. I also repressed in myself, as strenuously as I could, until the
very last of the cruise, all disposition to form hypotheses ; for I saw that my opportunities for
observation were uncommonly favorable, and I wished to be faithful to my trust as an observer,
and to have facts that could be relied on, whithersoever they might lead. The consequence
of all this is, however, that there are incongruities and contradictions here and there in these
lines of Zodiacal Light, or, at least, what appears to us to be such. Had I allowed myself to
refer back, and so to guide myself along by former data, or to theorize, I could have made the
results more symmetrical and more harmonious ; but I declined seeking for symmetry, or even
consistency, at such a risk. An hypothesis to go upon is often useful in sharpening observa-
tion ; but it may also warp the mind and mislead, and I thought it would be too dangerous
here; and my observations are not only independent of hypotheses, but, from the causes just
stated, are independent also of each other.
It may seem to be, and perhaps is, inconsistent with the remarks just made, to say that, at
an early period, the idea of a nebulous ring around the earth came up in my mind as applying
more than any other to the case, and that it remained there to the last. I could not help think-
ing; and in those long, silent, night watches, thoughts of this kind would often be busier than
I wished them to be. But I still tried to be faithful to my work as an observer, not a theorist ;
and if I swerved from this dirty, I am not conscious of it, except in a single case. That excep-
tion I regret. It was where I had seen a light in the evening, ascending high in the eastern
sky, (see July 7th, 9th, and August 5th, 1853,) and noticed it several times again the follow-
ing year ; but, concluding that it ought not to be the Zodiacal Light, I failed to make record of
it at the latter period.*
My first observations were of an awkward, and for a long time they were of a very desultory,
kind. I contented myself with making records of having seen the Light, and with giving its
boundaries, by written descriptions, in a general way. But the necessity of precision soon
showed itself; and, as I went on, of yet still greater precision ; and I then constructed a star-chart
o P. S. Brooklyn.— I have regretted this still more since reading Baron Humboldt's remarks on this eastern light, in
the Astrommische .\".c, ',,,,/,/„„,/, x,,. 939 ; and also an article by Theodore J. C. A. Brorsen, in No. 998 of the same periodi-
cal. The latter calls it by a very appropriate name, gegenschein (a shining opposite), and informs us that he made continu-
ous observations on it for about two years. For a more extended notice of his observations, see the annotations in this
book, No. 42.
INTRODUCTION. XI
from our excellent little globe. By laying folds of paper below this, and sticking pins through
the stars, I multiplied the charts, till, after nearly a year's work in this manner, I was able to
have the chart cut in wood at Canton, and thus I found myself well prepared for work. My
custom was, at evening, to watch for the earliest appearance of the Zodiacal Light; and, as soon
as I could get reliable boundaries, to notice their course among the stars, and draw these bound-
ary-lines on the chart, with such annotations as the case might require; then, again, after the
interval of half an hour or an hour, to go out once more, and as the boundaries would be
changed in that time, to take the new ones in a similar way; and so proceed till the Light could
be no longer seen: and thus also, in a reverse order, in the morning. And after having once
fairly commenced — say about the first of March, 1853 — I never failed for one evening or morn-
ing, (Sundays always excepted,) till our reaching home on the 22d April, 1855, to see, and,
with one exception, to make record of the Zodiacal Light, when the moon and clouds did not
interfere to prevent. In the case of that one exception, I saw the Light; but being shut up
among the houses in Canton, I could not get reliable boundaries.
The development of facts in the Zodiacal Light came upon me gradually, and, before they had
disclosed themselves, much valuable time in the high southern latitudes, at the early part of
our cruise, was lost; on our return, however, we went still further to the south, and I was able
to make amends in some measure for this loss.
There is no mention made, in any books on the Zodiacal Light, of any differences in the Light
itself;* but I very soon began to notice that there was a Stronger Light at the central part, or
along the axis ; while, beyond this., on either side, and also above, a dimmer kind of light ex-
tended itself, as if the matter giving us this light was more condensed at its central parts, and
was thinned out beyond. I have called these the Stronger and the Diffuse Light, and have
marked the boundaries of the former on my chart by full lines, while the bounds of the Diffuse
are designated by lines of dashes, each having the hours of the observation affixed to it. Some-
times, beyond the Diffuse Light, there was also what seemed to be, not a positive light, but
rather as if the sky were slightly paled (if the reader will allow the word) ; so slightly, that
I could not trust my own sight respecting it, till I had called in repeatedly the aid of other
persons (see chiefly June 27th and July 1st to llth, 1853). I have marked the boundaries of
this last by dotted lines ; but I consider it only as the more Diffuse matter greatly attenuated
at its outer edge, which, by the sinking of the ecliptic towards the horizon, was now brought so
as to make its reflection visible to us. In the case just referred to — that of July — it presently
changed into the Diffuse Light itself. The Stronger Light is evidently the one of which
Cassini has given the boundaries in his written accounts.
It is not to be supposed by the reader that any of these kinds of light was bounded by sharp
lines easily detected in the sky. On the contrary, the Stronger passed by degrees into the Dif-
fuse, and the latter also gradually faded away. Yet there was, in the former case, a line of
greater suddenness of transition, which, when my eye had got accustomed to observations, I
was generally able to make out without much difficulty ; and this is the line or the boundary
which is given in my charts. The outer boundary of the Diffuse Light was also tolerably well
marked. That I was not fanciful in this, is shown by the frequency with which other persons
on board, both officers and seamen, when requested to do so by me, and without any leading
- I'nlrss, as Krcms prolalile, the following extract from Mairan's Trailf Physique d Ilixturirjiie tic I'Aurore Sor&ile, refers to
tiin-li u ilifli-roiicc : " J'ai encore observe1 plusieurs fois, qu'apres que la Lumiere Zodiaeale avait cessi! de paraitre le soir
SOUS sa furiiir .It- lauce ou de fuseau, Unite la partie du coudiuiit demeurait phis iVlaiivi- ijur la rrMr du del, sur 30 ou 40
<!' -HM •.-, d'amplitude." P. 36.
XII INTRODUCTION.
questions, drew boundary-lines winch corresponded exactly with those which I had just drawn,
mentally, myself. Sometimes they differed from me ; but still the promptness with which they
designated such boundaries is proof that the transitions were perceptible to the eye. Generally,
much careful looking took place, and perhaps repeated attempts, before I ventured to draw my
lines. Often I was in doubt after all possible pains-taking, and the doubts are noted down.
As a general fact, late in the evening the Stronger Light would melt away gradually, or rather
would seem to be merged in the Diffuse Light, which alone would be left, the latter at first
witli a degree of brightness greater than it lately possessed ; and then the Diffuse would pass
away, in the increasing night. In the morning, the reverse was the case. It should be here
observed, also, that this gradation in the strength of the Zodiacal Light was not only lateral
from the centre outward, but also from the horizon upward to the terminating point. But the
transition, in this latter case, was by insensible degrees, except in the cases of a more intense
light near the horizon (to be noticed soon, and marked by zigzag lines on the chart); even the
Stronger Light, towards its apex, was so dimmed as to be distinguished with great difficulty, and
often I could make it out only by following up the boundary-lines from the lower portion.
Sometimes, towards the last of these observations, I declined drawing the apex at all on the
charts. (See Nos. 310, 314, &c.)
I remember very well my feelings of surprise and wonder when the lateral changes in the
Zodiacal Light, as the night advanced, for the first time forced themselves on my attention.
Those changes, as may be seen from my charts, are of constant occurrence ; yet I do not find
them noticed in any writings on this Light, except an allusion by Cassini in one of his observa-
tions, in which, however, he tells us that, both then and afterwards, he could come to no certain
conclusions as to their existence.*
These changes, running all through the observations, will be found to be of great consequence
when we come to draw conclusions from our data. They are greatest and most striking when the
ecliptic has declined considerably towards the horizon; and there is great uniformity in them,
but they are not without contradictions among themselves ; as, for instance, No. 177, t where the
lateral change ought apparently to be on the other or northern side ; but these incongruities are
rare, and are probably owing to extraneous causes. J I would not advise any one to draw con-
clusions from exceptions, in a matter where mistakes can be so easily made by the observer, but
only from the general facts of this book ; I have put down all, exceptions and incongruities as
well as others, not feeling authorized to omit any portion; for who can say, in a new science,
that what seem to be exceptions are not a part of the general rule ?
Among the most important of these observations are those when the Zodiacal Light was seen
near and at midnight, simultaneously on both the western and eastern horizons — a circum-
•- •• Jo cloutai si die n'avait pas uu peu de mouvement particular vcrs le septentrion ; car Ics deux plus luisantes il'. \rics
qu'clle frisait an commencement par son cote septentrional, furent ensuite comprises dans cette clartg ; ce qui a e"te" depuis
mnl'miie' par Ics observations drs jours suivaus. Mais je ne fus pas en etre cntierenient assure* ni alors, ni apres plusieurs
jours, parceque rextremite" de cette darte" c'tait de tous cotes trop douteuse, a'afflaiblissant peu-'a-peu ; de sorte qu'il e'tait
cxtivmement difficile de la determiner pre"cisement. " — MCmoires de I' Academic Bm/ale Aea Sciences, torn. riii.
j So also No. 101, where the 3 o'clock observation does not harmonize with the rest.
{ Cassini remarks on the character of the Zodiacal Light as follows : " H ne faut ne'anmoins prt'tendre re"duire les appa-
ram-es ile rette lumicrr a un iV^U- aiissi cxacte que 1'anneau ile Katurne, parcequ'il s'cn faut beaucoup qu'clle soit si bien
termiui:e rt qu'cllu ait autant de consistence ; e'tant asscz evident, par les Jiil'rn -no-s uccidentalcs qu'elle fait paraitre d'un
jour a I'autiv, qu'rlle re'.'oit des variations reelles, outre celles qui viennent des causes externes, comiue des diversrs de'yres
de la darts' de 1'air et du concours de la lumicre desastres, et uieme de la disposition <1 •> \vux de 1'observatcur." — Mimoires
il r.[:<itliiiin /i'<»/"''', '""'. ''"'. fl'- ll>3. 161.
INTRODUCTION. XIH
stance never observed before.* I had not expected it, and the manner in which it carne upon
me is recorded in Nos. 93 and 94, with the care, also, to have other eyes than my own brought
to bear on the subject, and also my carefulness in watching the western and eastern skies
through all the changes of the light, from early in the evening till dawn. It is probable that
tli is appearance can never be seen except when the ecliptic at midnight is at right angles, or
nearly so, to the spectator's horizon ; which can only be the case where his latitude is equal to
the sun's declination, but on the opposite side of the equator. I saw this again in the follow-
ing year (No. 266, &c.) ; and in both instances the ecliptic was not only vertical, or nearly so,
at midnight, but bore east and west from me; but the latter circumstance, I presume, had noth-
ing tn do with the results. I have been puzzled to know by what kind of lines to designate the
boundaries of this midnight Light; for it was very dim, quite as much so as the Diffuse Light;
yet when L came to bound it by lines of dashes, I found they produced confusion when the Dif-
fuse Light itself was marked down ; so I gave it a line of alternate dashes and dots, and thus
it is designated in the charts.
Some time early in 1854, 1 saw in a newspaper a brief notice of the pulsations in the Zodiacal
Light seen at the Kew Observatory; but as the newspaper did not state where they were ob-
served, or the authority, and as I had now been observing for a year without having noticed
anything of the kind, I set it down as an ocular deception, and the thing passed entirely from
my mind. But in March of this year (see No. Ill), I was surprised, one evening, at seeing the
Zodiacal Light fade sensibly away, dimmed to almost nothing, and then gradually brighten
again. This was repeated several times ; but the effect, after all, was to leave me only in
amazement and doubt. Subsequent nights, however, gave abundant exhibitions of this kind,
of which, with the times and changes, I have made ample records with the particularity that
the case required. It was a great satisfaction, after my return home, to find that Baron Hurn-
boldt had observed the same thing while in southern latitudes, though he thought it more
probable that it was owing to "processes of condensation going on in the uppermost strata of
air, by means of which the transparency, or rather the reflection of light, may be modified in
some peculiar and unknown manner." My records, however, will show that there is a regu-
larity of appearance at the closing off of these pulsations, which proves that they do not belong
.to so uncertain a cause as atmospheric changes, but to the nebulous substance itself. They seem
to intimate a great internal commotion in the nebulous matter, for they were too rapid to be
occasioned by irregularities in its exterior surface.
I noticed them again the following year, but must refer the reader to my records and charts.
The changes were a swelling out, laterally and upwards, of the Zodiacal Light, with an increase
of brightness in the Light itself; then, in a few minutes, a shrinking back of the boundaries,
and a dimming of the Light ; the latter to such a degree as to appear, at times, as if it was quite
dying away ; and so back and forth for about three-quarters of aji hour ; and then a change still
higher upwards, to more permanent bounds.
A reference to the charts will show zigzag lines in some of them (see Nos. 288 and 323, and
almost passim) down near the horizon. These are the boundaries of a very effulgent light which
appeared at the times specified, and within these bounds. It has no other distinction than its
greater brightness, and the cause of it I cannot surmise. Cassini appears to have noticed the
° Unless, indeed, we cli-s this with what a German writer calls, the gegenschein ; for which sec notes to observation of
August 5th, 1S.">3.
XIV INTRODUCTION.
same thing, as will be seen by reference to his annotations quoted in this book, fronting the
chart 351.
I now, however, come to what may perhaps be the most important of all these observations ;
but a part in which my observations are meager, compared with the rest. I had, at an early
period, queried whether the moon might not give a Zodiacal Light, and had given attention to
the subject; but, probably, had looked too high up in the sky, and, at all events, had failed
to see anything of the kind. But, one evening, when I was finishing some boundaries from the
western sky, the quartermaster on duty said to me: "The moon is going to rise;" and, on
crossing the deck, I was struck at once with the resemblance between the light then showing
itself in the eastern sky and the morning Zodiacal Light, in every thing except its elevation.
In breadth, in the peculiar boundaries laterally of the Zodiacal Light, and in coloring, it was
all the same ; and, in its subsequent rapid changes, it still kept strictly within the Zodiacal
Light bounds. The following night I was prepared to make records; and I never failed after-
wards to watch for recurrences of such light. But they did not often present themselves ; for
the ecliptic should be at a high angle, otherwise the light is apt to be so scattered along the
horizon as to be unsatisfactory. It also happened, that we almost always had cloudy weather
when such observations are most desirable — namely, at the full of the moon. For what was
done on the subject, I must refer to the charts towards the close of this book, inviting attention
more particularly to the observations of February 14th and 15th, 1854, and also to that of
March 18th, of the same year, Nos. 331, 332, 335. In the last case, the Light appears to have
extended far up (78°) into the sky.
On two occasions March 6th, and December 25th, 1854, I had also an undoubted joint sun
and moon Zodiacal Light. That is, when, the moon was about its first quartering*, and, at the
time of the observations, about 63° above the western horizon, a bright streak appeared in the
western sky, along the ecliptic; the joint light from the sun and moon, reflected from the nebu-
lous matter, being apparently sufficient to overcome the bright moonlight in our atmosphere,
and thus to make itself manifest. On both occasions I brought other persons to look (in the
latter case, the captain and several other officers), whom I got to draw boundaries which corres-
ponded to my own view of the subject. The latter occasion was also the more striking, because
the streak of light did not stretch up exactly toivards, but to one side of the moon, that satellite .
having then a southerly latitude of four and a half degrees.
The observations here given commence on the 2d day of April, 1853 ; for, although I had
been a careful observer since December 22d of the previous year, I consider the interval as
having been necessary in order to gain experience, and I have consequently rejected all up to
the period mentioned. My first intention was to reject still more, and to commence this pub-
lication with June of that year ; but the extraordinary interest of some of the observations in
April, and the great care which I took in them to be precise as well as correct, have led me to
insert them. The unbroken series commences at No. 10, June Y, 1853. From that time, till
our arrival in New York on 22d April, 1855, every observation is recorded; and, except on
Sunday, I never once failed to have observations, if the moon or clouds did not prevent.
Of the whole body of observations, however, I consider the last as more entirely reliable than
the first; for I was all the while gaining experience, sharpening my observations by use. As
an example, the reader will perhaps notice that in the morning observations of August, 1853,
the Zodiacal Light boundaries are not carried as high up in the sky, as in the same month of
-• Mun-U 1854, lirst quurU-i tit I livniu ]• h li./. Hi. : Dr. rml.rr I>j4, do. t(>d On. Jim.
INTRODUCTION. XV
the succeeding jrear. It is probable that, in the former case, the Light extended further up than
is recorded — perhaps as far as in the latter case; but my eye then not being so accustomed to
trace tin- dimmer markings of its higher portions on the sky, I failed to observe them. Some
morning observations which I have made since my return home in August, 1855, confirm the
higher altitudes. I was also, at first, not sufficiently careful in getting the exact curve of the
effulgent Light (see Nos. 197, 199, &c., compared with 313 and 323, &c.), having been con-
tented simply with noting the altitude of that peculiar brightness.
It will be seen that there is a full line with dots beneath, towards the upper part of most of
the charts. These lines represent the course of the spectator's zenith for the hours given, and
are intended to show his change of place as regards the ecliptic ; so that we may know whether
such changes have any connexion with the changes in the Zodiacal Light. They seem to have
a very close and pretty uniform connexion. We must bear in mind, however, that these lines
are his course projected on the sky, and that his real change of place is of infinitesimal amount
compared with what we see it in the chart. Where there is but one observation, his zenith is
represented by a dot with a circle around it. If his zeniths are beyond the limits of the chart,
they are given in the opposite records. When the sun also could not be entered on the chart,
his longitude is given on the opposite page.
In addition to this remark about the greater reliability of the latter portion of these observa-
tions, I would caution the reader against drawing conclusions from isolated data, if contrary to
the general mass. In a matter so indefinite as the Zodiacal Light, and where mistakes are so
easy, I was constantly liable to be misled ; yet where appearances seemed to differ from those of
the ordinary character, I never considered myself at liberty to do otherwise than to give them
with their incongruities. But still, as already remarked, I should consider it dangerous to
draw conclusions from such, or, at present, from any other than the general facts.
My opportunities for observation, it will be seen from these records, were very good. Of the
seven hundred and fifty days included in my observations, three hundred and twenty-eight were
spent within the tropics; and, in the balance of the time, our cruising extended from 41° 49'
N., to 53° 28' in the south. The light always appears to best advantage near the equator; but
we shall see, also, that the changes in latitude, from high north to high south, were of the
iitrnost consequence, as regards results.
Whenever new phenomena, which were constantly occurring, threw me into doubt, and made
me distrustful of my own eyes, or needing confirmation of their correctness, I could always find
help among the night-watchers on deck; and also a choice of help, for sometimes I needed the
aid of intelligent persons ; and sometimes of others, who, without knowing what was meant,
could only look, and tell me what they saw. My state-room was also on the quarter-deck, and
within ten feet of the sentry at the cabin-door, who could wake me at any mimite, for which
orders had been left.
But though frequently calling in the aid of other eyes, as just described, and with very valu-
able results, still the observations here given are all my own ; for I was satisfied at the outset
of the importance of one pair of eyes and of one judgment, to see and decide in every case. And
thus, although for six consecutive months, so sick as often to be unable to walk or stand without
support, I still kept to my work; and the result, whatever it may be worth, has the merit of one
uniform judgment trained by some experience, and stimulated, I know, by deep earnestness in
the cause.
XVI INTRODUCTION.
But I consider this as only the commencement of work. We need more facts. Those in
this book are very few, compared with what are required in the case. It is my own purpose to
make further observations, if possible, for a year or fifteen months, at some one spot, at or near
the equator, so as to have comparisons, as the ecliptic passes at equal distances over head in the
different portions of the year. And if my life is spared still further, I hope to continue my
work to its end.
But we need many observers. One judgment may make mistakes — many of them, where mis-
takes can so easily be made. We need many judgments, so that one may correct another ; and
especially is it desirable that, for one year at least, there should be a series of simultaneous
observations at the equator, and at points remote from it, both at the north and south. This
I hope to be now able to effect.
At this stage of our work, effected and proposed, it may, perhaps, seem to be premature to
draw conclusions ; but still there are certain things that seem to force themselves on the mind
from the data here afforded ; and, if the conclusions which I shall now proceed to draw are not
decisive to the reader's mind, they can at least furnish subjects for discussion that may, in the
end, bring us to the truth.
DEDUCTIONS FROM THESE OBSERVATIONS.
§1-
It seems to be quite conclusive, on an inspection of these charts, that ive never, at any
one time, see the whole actual extent of the Zodiacal Light. This subject can, perhaps, be eluci-
dated by noticing a common event, — a cloud, silvered at one edge by the rays of the declining
sun. The sun may be shining on the bordering, quite around that cloud; and, if so, it is send-
ing off, from every portion of the border, an equally brilliant, silvery light. But our eye is in a
position to catch this reflection from only one portion of it, and the rest is dull to our vision.
If we could with great rapidity change our positions, other portions of the silvered edge would
show themselves according to our changes of place. So, also, when a rainbow is presented to
our eye : the myriads of drops of falling water in the whole rain-shower are sending off, from
each drop, reflections of light in all directions, and the universal atmosphere about us is full
of these brilliant, variously-colored rays ; but only that portion which, to us, forms the rain-
bow-arch, can reach our eye, and all the rest is lost to our sight.
So it is also with the Zodiacal Light ; and the proof that we never see the whole of its
extent at once, is manifest in the following facts:
1 . That when I was in a position north of the ecliptic, the main body of the Zodiacal Light
was on the northern side of that line.
2. When I was south of the ecliptic, the main body of the Zodiacal Light was on its southern
side.
3. When my position was near or on the ecliptic, this Light was equally divided by the
ecliptic, or nearly so.
4. When, by the earth's rotation on its axis, I was, during the night, carried rapidly to or
from the ecliptic, the change of the apex, and of the direction of the boundary-lines, was
equally great, and corresponded to my change of place.
5. That, as the ecliptic changed its position as respects the horizon, the entire shape of the
Zodiacal Light became changed, which would result from new portions of the nebulous matter
INTRODUCTION.
xvn
coming into position for giving us visililc reflection : while portions l;)lely visible, were no longer
i;-ivitio- us such a reflection.*
: The lirst. f'»m- of these results were ni>t always uniform ; hut the exceptions were tew, ami wrrr probably occasioned by
the nrliiikins ring's nut lyinu exactly in the ]ilai I' the elliptic. In order to afford (he reader a comprehcn>i\ e glance at
tlii-, very important anil interesting part of our subject. I have drawn out a table. ;:mir_: tin- number of each chart, and its
bearing upon tin- above four general facts : jJ'i« simiihing that the oKsei vation was in 1'avor of, and minus ap-ainst. that one
«S the farts whose number immediately follows. An asterisk to any number signifies that the observation referred to is
of particular force. A note of iuten-.^ation means that the case is doubtful. The reader is especially requested to com-
pare the evening observations of October. IS.Vi, with those of December, in the same year. In both cases I was in the
same latitude ; hut in October, I was far north of the ecliptic, in the evening ; and in December, was nearly on that line ;
and the change in the Zodiacal Light boundaries is correspondingly great. Compare also the evening observations of
March 16th, 1855 (No. 303), with the morning observation of the same night (No. 304). In the former case I was far
removed from the ecliptic ; while, before morning, I was brought close to it, with a corresponding change in the place of
the Zodiacal Light. Compare also the whole series of observations from Nos. 49 to 82 ; where, in the morning, I was near
the ecliptic, and in the evening, far removed from it. Observe also how, as in the latter part of October, and in Novem •
ber of that year (1853), I was each evening drawing rapidly more and more towards the ecliptic, the Zodiacal Light was
also rapidly withdrawing from the north, and was drawing up towards the ecliptic line.
In constructing this table, I have had reference chiefly to the Stronger Light, as giving us the most reliable data.
No. 1 — 1
No. 48 + 1
No. 95 + 3 — 4
No. 142 + 1
No. 183 + 1
No. 236 — 1
No. 283 + 2
2 — 1
49 + 1
96 + 3
143+ 1
190 + 1
237—1
284?
3 + 3
50+1
97 + 3 + 4
144 + 1
191 + 1
238 + 3 — 4
285 + 2
4 + 1
51 + 1
98 + 3
145+ 1
192+ 1
239?
286 + 2
5 + 1
52 — 1
99 +
146+ 1
193 + 1
240 + 1
287 + 2
6+1
53 + 3
100 +
147 + 1
194+1
241 + 1
288 + 2
7 + 1
54?
101+ + 4
148+1
195+1+4
242+ 1
289 + 2
8+1
55 + 3
102 +
149+ 1
196 + 1
243+ 1
290+2
9+1
56+3
103 +
150+ 1
197 + 1
244 + 1
291 +2
10+ 1
57 + 1
104 + 3
151 + 1
198+ 1
245+ 1
292 + 2
11 + 1
58 + 1
105.'
152 + 1
199 + 1+4
246 + 1
293 + 2
12 + 1
59 + 1
106 + 1
153+ 1
200+ 1
247 + 1
294 + 2
13?
60 + 3
107 + 1
154 + 1
201 + 1 + 4*
248 + 1
295 + 2*
14 + 1
61 + 1
108 + 1
155 + 1
202 + 1
249 + 1
296 + 2
15 + 1
62+1+3
109+ 1
156+1+4
203+1+4
250+1—4
297 + 2
16 + 1
63 + 1
110+1 + 4
157+ 1
204 + 1
251+1—4
298?
17 + 1
64 + 3
111 + 1
158+ 1
205 — 1
252 + 1
299?
18+ 1
65 + 1
112 +1+4
159+ 1
206 + 1
203 +1+4
300 + 2*
19 + 1
66 + 3
113 + 3
160 + 1
207 + 1 + 4
254+1+4
301 + 2*
20+ 1
67 + 3 + 4
114 + 1 + 4
161 + 1
208 + 1 + 4«
255+ 1
302 + 3
21 + 1
68 + 1
11.-, + 1+4
162 + 1
209 + 1 + 4«
256+1+4*
303 + 2'
22 + 1
69+ 1
110 + 1
163+ 1
210+ 1 + 4*
257 + 1
304 + 3
23 — 1
70 + 1
117?
164 + 1
211 — 1
2.-.S + 1
305 + 2'
24 + 1
71 + 1
118 + 1
165+ 1
212 + 1
259+1 + 4*
306 + 3
25 — 1
72 + 1
119 + 1
16G + 1
213+ 1
260 + 1—4
307 + 3
26 + 1
73+1
120 + 1
167 + 1+4
214 + 1
261?
308 ?
27—1
74 + 1
121 + 1
168+1 — 4
215+ 1
262 + 1 ± 4
309 + 3
28 + 1
75 + 3
122 + 1
169 + 1
216 + 1
263+1—4
310 + 3
29+ 1
76 + 1
123?
170+ 1
217 + 4
264+1—4
311 +3
30+1
77 + 3
124+ 1
171 + 1
218+ 1
265 + 1
312 + 3
31 + 1
78+1+4
125
172 + 1
219 + 1 + 4*
266 + 3
313 + 3
32
79 + 3
126 + 1
173 + 1
220+ 1
267
314
33+ 1
80 + 1
127 + 1
174 + 1
221 + 1 + 4*
268 + 4
315?
34 + 1
81+3
128+ 1
175 + 1
222 +1 + 4'
269 + 4*
316 — 3 — 4
35+ 1
82+1
129 +. 1
176 + 1
223 — 1
270 + 4*
317?
16- 1
83 + 1 + 4
130 + 1
177 + 1
224 + 1
•J71 + 1
318—3
37+1—3
84+1 + 4
131 + 1
178+ 1
225+ 1
272 + 1
319?
38+1
85 + 3
132 + 1
179+ 1
226 + 1
273 + 2 + 4«
320+ 1
39 + 1+4
86 — 1
133 + 1
180+ 1
227 + 1
274 + 2
321 + 1
40 + 1
87 + 3
134+ 1
181 + 1
22* — 1
•„'•,.•, + 2
322 + 1
41 + 1
88 + 3
13.-, + 1+4
182 + 1
229+ 1
276 + 2
323+ 1
42 — 1
89 + 3
136 + 1 + 4
1S3 + 1
230+ 1
277 + 2
324 + 1
43— 1
90 + 3
137 + 1
184+1
231 + 1
278+ 2
325+1
44 + 1
91+3
138+ 1
1S5+ 1
232+ 1
279 + a
326 + 1
45+1
92 + 1
139 + 1+4
186 + 1
233+ 1
280+ 2
327+ 1
46+ 1
93 + 3
140 + 1 — 4
187+ 1
234 + 1
281 +2
328+ 1
47 + 1
94+1
141 + 1—4
188+ 1
235+ 1
282?
z 3
XVIII INTRODUCTION.
§H.
A plane, pa-ssing through the centre of the Zodiacal Light, as it shows itself through the varying
latitudes of these observations, would correspond pretty nearly loitli the ecliptic;* but how near the
two planes approach to a coincidence, it seems to be yet impossible to say. Through all of
April, 1853, and December, 1854, there appear to be proofs of an evident crossing of the two
planes. Through July of 1854, the apices, in the evening, were decidedly on the northern
side of the ecliptic, though my latitude was only about 25° N. ; while, in September of the
same year, though my latitude was nearly as before, the apices were on the southern side of
the ecliptic, as shown by my morning observations ; the mornings then being very favorable
for correct observation, on account of the high angle of the ecliptic with the horizon. Again,
in April, 1855, the apices, and greatest body of the Light, were north of the ecliptic, even at
times when I was, myself, to the southward of that line ; as was the case in the first hours of
the evening observations, up to the 13th of that month. The following general view rather
shows us that there is something on this subject which may yet be learned, than that we have
now the materials for anything definite and certain on the subject.
1853. April. — The planes of ecliptic and Zodiacal Light cross each other.
July. — By evening observations, the apex of Zodiacal Light appears to be north of the
ecliptic. Morning observations are not satisfactory, either way.
1854. March 27 to April 18, strong proofs of crossing of the planes, by both morning and
evening observations.
July. — Apex decidedly to the northward, by both evening and morning observations.
September. — Apices on the south, by morning observations, during this month.
December. — Apex decidedly to the northward, through all this month.
1855. January. — Apex as decidedly to the south of the ecliptic, by both morning and evening
observations.
March. — Apex south of the ecliptic, by evening observations; the morning observations
place it on the ecliptic.
April. — Apex north. No signs of a crossing of planes.
§111.
This Light cannot be a reflection from our atmosphere, taking its shape from that ; for this
atmosphere, though brought, doubtless, by the axial motion of the earth, into a somewhat len-
ticular shape, must have its elongation directly over the earth's equator; and the course of the
Zodiacal Light shows not the slightest affinity to the equatorial line.
§IV.
This Light must be from something continuous and unbroken; not from a detached periodic body,
either spherical or elongated ; for, during more than two years' uninterrupted observations, I
never failed to see it, either evening or morning, when the moon and clouds did not interfere.
c Which is the reason why I have chosen the ecliptic for the central line of my charts ; and why I refer so often to the
position of the spectator as regiyils the ertijitic.
INTRODUCTION. XIX
§ V.
May not tins Light be from a nebulous body of lenticular shape reaching to the sun, and lying
in, or near, the plane of the ecliptic ?
This query, I believe, comprehends Mairan's theory; and also that of many others of our own
time, who, having abandoned part of his opinions, still hold to the lenticular shape. Mairan's
idea of such a body connected with the sun, and revolving with that body, must be abandoned,
for the reasons shown in page vii of this work. But may there, still, not be such a lenticular-
shaped body, with the sun for its centre, yet not revolving with that luminary, but having a
rotatory motion of its own?
The idea of a lenticular shape has doubtless arisen from the peculiar outline of the Zodiacal
Light as presented, in its best and strongest aspects, to our eye. This Light being somewhat
lenticular in shape, the body producing it is supposed to be similar in shape. But we must
remember that, in order to draw such an inference, we must be without this lenticular body,
looking down upon it; and that, to admit of this, its extent must fall short of our earth. But if
it falls short of our earth, I could not have had the Zodiacal Light on both the eastern and west-
ern horizons at midnight; nor could it, in any observation, have reached far up in the sky; it
could never, by any possibility, reach the spectator's zenith, which the Zodiacal Light is known
very often to do.
If we suppose this lenticular nebulous body to involve the earth, and the spectator to be in its
ruidst, looking through it, then the argument for a lenticular shape loses its force ; for any other
shape may give us such a result, if such a result can be given at all. But we may very well
query, whether, if involved in the nebulous matter, and looking through it, we could get any
distinct outlines by reflection from its particles, any more than, when involved in a fog, or in
smoke, or in our earth's atmosphere, we can get their outlines. It is true that, when extrane-
ous matters are mingled with these, we may get marked lines or boundaries in them, as we often
do in our atmosphere from humidity along the horizon ; but all this is from causes extraneous,
and is not from the atmosphere itself; and it is also temporary in its nature.
It may also be said, that if we are involved in this nebulous matter, portions of it may give
a reflection reaching our eye, while others do not ; as it was asserted in § I that this matter
actually does. Yet still it may be a subject of strong doubt, whether, if thus involved, the
reflections could come to us with any such strongly-marked character, and with such distinct
outlines, any more than they can come from our own atmosphere alone, while we are involved
in its particles. My own impression is, that they could not.
There are, however, other difficulties in the way of this theory, which I will proceed to state:
1. This lenticular body having, in order to sustain itself, to rotate on an axis (which axis
must be at the sun), and its diameter being more than 190,000,000 of miles, its portions near
the centre and at its outer edge would require velocities entirely incompatible with each other.
Either the inner portion would be drawn to the sun, from the want of centrifugal force; or the
outer would fly off and be lost, from an excess of it; or the whole body, more probably, would
soon resolve itself into a series of concentric rings, with intervals between them, somewhat accord-
ing to Laplace's theory of the formation of our planetary system. But that there are no such
concentric rings in this case, giving, by their combined effect, the Zodiacal Light, is evident
from the fact that the light is continuuus and regular, not broken into cross-bauds or mottled,
as would be the case, if from a number of concentric rings.
XX INTRODUCTION.
2. In tlie annexed figure, constructed to elucidate this theory, let A B C D Gr represent the
outer edge of this supposed nebulous lenticular body ; S, the sun ; E, the earth ; let the line Gr
H be in the plane of the horizon of a spectator on the earth; taking for illustration the obser-
vation of September 4th, 1854, at 4h 30m a. m.; which observation is selected, not because it is
of more applicability than any others in the book, but because it is a simple case, and because
the observer at 4h 30m being near the ecliptic, a cross section a b c c d d of the lenticular body
would be very nearly in the plane of his horizon; so nearly, that, in our reasoning, they may be
considered the same. The lines of the spectator's horizons, of sufficient correctness for illustra-
tion, back to midnight, and also lines to his zeniths, are given on the diagram. The lines eee,
fff, g g y, li h h, i i i, may represent the boundaries of the Zodiacal Light at 4h 30m, 3b 30m,
2h 30m, lb 30m, and midnight ; the points where each set strikes the horizons or sections abed,
&cv in the nebulous lenticular body, being at the option of the reader.
Now it will be obvious, that, from whatever portions of the lenticular body the Zodiacal Light
comes reflected to the spectator at E, it must grow narrower as we recede back from the hori-
zon at 4b 30m, by the different horizons to that of midnight, the base g g, in the horizon at 2h
30m, being much narrower than that of e e, in the horizon of 4h 30m ; and so to midnight, when
the width must become very greatly reduced. But there is no such change in the actual width
of the Zodiacal Light itself; but, on the contrary, though the various hours of the night make
themselves felt decidedly in its brightness, they give us no perceptible change in its breadth;
the base of the great body of the Light at 2h 30m having, usually, as great a width as at the
dawn. Certainly there is no such a regular increase of breadth in the morning, or reduction in
the evening, as such a theory would necessarily demand.
3. Objection 1 could be obviated by supposing the inner portion of this lenticular body re-
moved, and only the outer part ABCDLMNO left as a ring enveloping the earth, retaining
still its lenticular shape, of which A L M would represent a cross-section. In that case the lines
a b e would have to represent the boundaries of the Zodiacal Light ; and it will be seen that
from, somewhere about Oto a b, these lines would have to be nearly parallel to each other, while
from 0 to e they would have a different course; and, indeed, the whole shape of the Zodiacal
Light would change, and be different in the different hours of the night, according as the hori-
zons change; whereas one of the greatest characteristics of this Light is the regular uniformity
of its shape.
4. There are two great laws with regard to light, from which a strong objection to this theory
would probably arise ; but it is difficult to apply them, in consequence of the uncertainty re-
specting those portions of the lenticular body from which the Zodiacal Light may be supposed
to proceed. The laws referred to are : 1, That when light is reflected to the eye, the quantity
reflected is in proportion to the greatness of the angle between the lines of incident and reflected
light; and 2, that the strength of light is inversely as the squares of the distance of the object
from which it proceeds. I shall, when considering Laplace's theory, apply these laws with
more particularity; but, on account of the uncertainty referred to, can only advert to them in
the present case. As the reader may wish to return to this diagram, and to study their appli-
cation to it, I will add here the dimensions of the angles, which, in the imaginary case,
would lie between the lines of incidence and reflection. They are, S m E, 91°; S H E, 97°;
S o E, 89° ; S r E, 89° ; S t E, 74° ; S v E, 21° 30' ; S w E, 38°.
5. It appears to me, also, that if this substance involved the earth, the earth and moon, or
one of them at least, would feel its effects upon their motions. The moon, in its revolution
INTRODUCTION.
XXI
SU1TOSED XEBfLOUS BODY OF LENTICULAR SHAPE, THE SUN FOR ITS CENTRE, AND INVOLVING THE EARTH.
XXII INTRODUCTION.
around our planet, would have this nebulous matter, in one half of its revolution, with it, and in
the other half, against it ; and let the nebulous matter have what tenuity it may, this difference
would be perceived in the increased or retarded velocity of the moon ; but no such difference of
velocity is ever perceptible.
6. Our globe, having this matter close about it, would, by its superior attraction, soon draw
its particles to itself, and make them a part of its own distinct existence, either as a ring to
itself, or in some other way.
§ VI.
The great nebular theory of Laplace, according to which we have, in the formation of globes ;
first, an immense body of chaotic, nebulous matter, revolving about its own centre; next, a con-
centrated, central portion, producing, or being the sun, with the balance of the nebulous matter
formed into a succession of concentric rings, according to the various specific gravities of the
matter itself, all still revolving around the sun ; next, these rings broken, and each rolled into
a spheroidal mass rotating on its axis, and still also revolving about the sun, and thus giving
us the various planets of our solar system ; with a remainder of this ring matter too volatile for
such condensation, and still continuing to form a nebulous ring around the sun, giving us, by
reflection from its particles, the Zodiacal Light, — has been the theory usually adopted to account
for this Light, since the publication of the Systeme du Monde. Laplace supposed this rotating
ring to lie somewhere between the orbits of Venus and Mars, having, as just remarked, the sun
for the centre of its motion.
Such a ring must be, necessarily, in one of the following cases : 1st, Within the earth's orbit ;
2dly, involving the earth; or, 3dly, without the orbit of the earth.
§ VII.
1. It cannot be within the earth's orbit, for the reasons advanced in the § V — namely, that
if so, we could never have the Zodiacal Light, at midnight, on both horizons simultaneously;
and could never have it at any great altitude, at any period of the night.
2. Involving the earth. The objection that if involved in the nebulous matter, we could not
get outlines, or have any figure shaped by reflection from its own particles, as stated in the first
part of the § V, will apply equally to the ring now under consideration. So, also, will objec-
tions 4 and 5 of the same § ; for, although Laplace supposes that the ring may have a motion
equal to that of the earth, or so nearly equal as not to make itself felt in the annual revolution
of our globe, yet the moon in each of its revolutions would have to feel the unequally retarding
force of this nebulous matter, and would show the effects in every revolution.
The laws of optics, soon to be noticed in detail, would also apply as an objection to such a ring,
with a force that seems to be irresistible.
§ VIII.
A ring beyond the orbit of the earth. — For the consideration of this, I have constructed a dia-
gram, in the centre of which is the sun ; E, at the intersection of the lines of horizons, is the
earth; and the dotted circle is the supposed nebulous ring, at an unknown distance from E,
which distance we will suppose to be represented by the unknown quantity x.
INTRODUCTION.
XXIII
XKHULOrS RIXC. AROUND THE SDN.
We apply to this diagram, as a fair example, the morning observation of September 4, 1854:
lat. 22° 18' North. Sun rose at 5h 48m; last observation of the morning 41' 30"1; previous one
3h 30m. Let E H be the spectator's horizon at 4h 30m, and E H1 at 3" 30ra. Then E N will
equal 158,900,000, and E M 179,100,000 miles*.
Let ABC represent the boundaries of the Zodiacal Light at 4h 30", and D E F at 3h30m; B
EOF being the southern boundary, which was permanent; and A G C and D F the northern
boundaries, at those respective hours. Now, by referring to the chart for that observation, it
will be seen that the opposite sides of the Zodiacal Light, which, at 3h 30"1, at its base, were sepa-
"- Tin- reader will see that mathematical precision can scarcely be attempted in these numbers ; they are offered only as
such careful approximations as the case will admit of ; but these are hcra sufficient.
XXIV INTRODUCTION.
rated by the distance DE; at 4h 30m in the same place were separated only by G E, being
3°, or 8,327,000 miles (+ the result of a-) nearer to each other than at 3h 30m. My own lateral
receding northwardly from the ecliptic, during that time, was 236 miles.
Apply other cases, for which the same diagram will answer, with such changes as the reader's
intelligence will easily supply.
January 30, 1854.— Morning: lat. 26° 10' N. Sun rose 6h 48m 30s. In this case EN =
141,200,000 miles : the lateral change D G from 4h to 5" was 27, 020, 000 miles -f the effect of
x. My own lateral change from the ecliptic was 345 miles.
November 20, 1854.— Morning: lat. 36° 17' N. Sun rose 6h 46m. EN ==142,300,000 miles;
the lateral change, D G, from 4h to 5'1 was 12,450,000 miles, -f- the effect of x. My own lateral
change from the ecliptic was 185 miles.
January 9, 1855. — Evening: lat. 8° 47' N. (The same diagram, reversing it, will answer
for this.) Sun set 5" 52m. E N == 161,000,000 miles; the lateral change D G from 7" 20m to
8h 20m was 7,740,000 miles -4- x. My own lateral change from the ecliptic was 245 miles.
March 16, 1855.— Evening: lat. 22° 55' S. Sun set 6" 12m. E N == 169,300,000 miles ; the
lateral change from 7" 30m to 8h was 5,912,000, and from 7h 30m to 8h 30m was 12,780,000 miles.
My own lateral change from the ecliptic in the half hour commencing from 7h 30m, was 85 miles ;
in an hour, 205 miles.
These examples are taken as fair ones of lateral changes in the Zodiacal Light : much stronger
ones abound in the book, and especially when the ecliptic had a low inclination to the horizon.
The query now arises, can such lateral changes, so uniformly observed as the evening or
morning advanced, agree at all with the idea of a nebulous ring giving this light at a distance
from the spectator of 160 or 180 millions of miles? A ring of the character supposed, it seems
to me, could give us a Zodiacal Light only of one uniform shape — namely, with the opposite
boundaries receding from each other for a short distance from the apex, and then running
parallel, one to the other, the whole way down to the base. Nor could the hourly changes of
time produce any other change in these boundaries than a rising or sinking of the apex of the
Light; the boundaries, say at 9 o'clock, p. m., extending a little higher in the sky than at 8 ;
but, immediately after leaving the apex, running into those of 8, and so continued, with a
parallelism of the opposite sides, clown to the horizon. How different this is from the true facts
of the case, almost every chart in this book will testify.
The evident and most decided connexion between these boundary-lines and the spectator's
place, as regards the ecliptic, is also a matter of the greatest significance in drawing our conclu-
sions respecting the origin of this Light. In § I, of these deductions, this matter is stated in
detail. Now, supposing the base of the Zodiacal Light to be at a distance of 200,000,000miles:
how is it possible that the fact, that the spectator is a short distance north or south of the eclip-
tic line, can govern the reflection from the nebulous ring at that immense distance, and place it
on his side of the ecliptic? If he is on the north side, not only is the main body of the Light,
down to its base, on that side; but the lateral changes of the boundaries, as the hours pass, are
altogether or chiefly on that side; and so equally with the south. And so, if he is on the
ecliptic, or near it, the Zodiacal Light stretches equally, or nearly so, on each side of that line.
Also, if he changes rapidly during the night to or from the ecliptic, the boundaries of this Light
also change, being regulated by his motion. That the apex of the Zodiacal Light, from such a
ring around the sun, might be so affected by the spectator's position, is not an unreasonable
supposition, since the ring may approach the earth sufficiently for such a result; but, that the
INTRODUCTION.
XXV
boundary-lines toward, and at, the base, should be so affected, seems to be utterly inadmis-
sible.
It is worthy of remark, also, how even and uniform, from apex to base, the change in the
boundary-lines is, as the hours change ; as if the substance giving the Zodiacal Light were not
only near, but also atone uniform distance from the spectator; the portions of it at the apex and
base of the Light all equally affected by his changes on the earth.
We come now to apply to this case the two laws of light referred to in § V; and I will give one
of them more in detail, leaving to the reader to apply them also to the diagram in § V, accord-
ing as he may choose his positions there for the Zodiacal Light.
A great number of experiments on the strength of light reflected at various angles have been
made in France, and are given by the experimenter, Mous. Bouguer, in his Traite d' Optique sur
la Gradation de la Lumiere. He says: "But what is more remarkable in the mathematical sur-
faces which we have just been considering, is the fact that the reflection is not equally bright
under all the angles of incidence.* In general, it is stronger under small angles, and more
feeble under larger ones. The difference is exceedingly great when the rays strike, with differ-
ent obliquities, the surface of very transparent bodies, but it is nearly as great in cases of cer-
tain opaque bodies; and I have never known it to fail altogether in any."
Among the results of his experiments, he gives us the following tables, in which are shown
the number of reflected rays out of 1,000, falling, at various angles, on a smooth surface of water,
and on mirror-glass not quicksilvered. I have added a column converting his angles of inci-
dence into the angles between the incident and reflected rays.
WATER.
MIRROR-GLASS NOT QUICKSILVERED.
Decrees uf angles of
incidence.
Degrees between the
lilies of incidence and
reflection.
Number of rays reflected
out of 1,000 incident
rays.
Degrees of angles of
incidence.
IV-rrrs bruveen the
lines of incidence and
reflection.
Number of raj's reflected
out of 1,000 incident
rays.
^
179
ITS
177
176
175
170
165
160
155
150
145
140
130
120
100
80
60
40
0
721
692
669
639
614
501
409
333
271
211
17S
145
97
65
34
22
19
IS
18
2.?
175
170
165
160
155
150
140
130
120
100
SO
60
40
20
0
584
543
474
412
356
299
222
157
112
57
34
27
25
25
25
1
5
1}
7J -
2
10
2\
m
5
15 ...
7J
20
10
25
121
30
15
40
17}
50
20
60
25
70
30 ...
80
40
no
50
60
70
90
The want of entire certainty in applying such results to the present case of nebulous matter,
must be conceded; for we know not what nebulous matter is, and we cannot go beyond sur-
= I'.y un^lr nf incidence, as he informs us, he means the angle between the incident ray and the HiirtVice of the reflecting
body — "avcc la surface et nonptisavee saperpentliculnin ."
XXVI INTRODUCTION.
raises as respects most of its properties: yet it is evident to our senses that Bougucr's law, that
the quantity of rays reflected is greater, the greater the angle "between the incident and reflected
light, applies to vapory particles (as we see in the reflection from clouds), and also to the mole-
cules of our atmosphere; and we may, I think, presume that it applies also to nebulous matter,
which, though seemingly a dense substance, has still nearly the transparency of our atmo-
sphere.*
Eeferring now to the diagram, we find that, at the base of the Zodiacal Light, at 4h 30m, the
angle hetween the incident ray S B, and the reflected ray B E, is 15° ; at the base at 3h 30m, it is
25° ; at 2h 30m, it is 36° ; and at 1" 30ra, it is 45°. Thus the angles, we perceive, go on increas-
ing from the horizon at 4h 30™ up to that at midnight ; and allowing that, below 40° between
the incident and reflected ray, there is no perceptible difference in the quantity of the reflected
light, we should from this law have the Zodiacal Light of the same intensity the whole way,
from the base at 4h 30°, up to its apex. But the other law of optics referred to — namely, that
the strength of light is inversely as the squares of the distance of the object affording the light —
would here make its application; and this ring at our zenith being about 140,000,000 of miles
nearer to us than at the base at 4h 30m, we should then have the Zodiacal Light far more intense
at the apex than at the base; at the base, at 2h 30m it would be much stronger than at 3h 301";
and at 31' 30'" stronger than at 4h 30™ ; all which is entirely opposite to the facts of the case.
§IX.
I offer now, as a last conclusion, the hypothesis of a nebulous ring, with the earth for its centre. —
There are certain deductions which appeared to come up in the examination of the preceding
theories, which I will now bring together, and exhibit in a united form. They are: 1. That
the substance giving us the Zodiacal Light must be equally near to us in all its parts, inasmuch
as the lateral changes of the Light — i. e. the changes of boundaries — have a uniform charac-
ter, and mostly a parallelism in their whole extent from apex to base; 2. That no part of this
substance can be very remote from us, inasmuch as the outlines of the Light were clearly and
decidedly affected by my own position on our globe, and even by my change of position, in a
single night ; and 3. That the laws of reflected light require an arrangement, or a shape, of this
nebulous matter, which will give us, at the base of the Zodiacal Light, larger angles between
the lines of the incident and reflected light, than at other portions, and also a regular decrease
of such angles from the base to the apex of the light, as produced by such a shape. These
three requirements appear to be fully met by an hypothesis, which, if the theories examined in
the preceding § are untenable, is now the only one remaining to us.
The hypothesis is that of a ring around the earth.
The thought is a somewhat startling one, yet startling only from its novelty ; for it is entirely
in accordance with what we know of one of our sister planets (Saturn), and also with the whole
of Laplace's celebrated theory of the formation of globes.
That great writer, after stating his ideas of the central condensation from an immense body
of nebulous, rotating matter, and thus of the formation of our sun, and of the rings about him,
produced from the remainder of that nebulous matter, thus proceeds :
"If all the particles of a ring of vapors continued to condense without separating, they
would at length constitute a solid or a liquid ring. But the regularity which this formation
° I could, in clear nights, with the naked eye, easily make out stars of the Cth, and I sometimes thought of the 7th mag-
nitude, through its densest parts.
INTRODUCTION. XXVII
requires in all the parts of a ring, and in their cooling, ought to make this phenomenon very
rare. Thus, the solar system presents hut one example of it — that of the rings of Saturn.
Almost always each ring of vapor ought to be broken into several masses, which, carried on
with velocities differing little from each other, would continue to circulate at the same distance
around the sun. These masses ought to take a spheroidal form, with a movement of rotation
in the direction of the rotation, since the inferior molecules have a motion less than the supe-
rior ones; they have thus formed so many planets in a state of vapor. But, if one of them has
been sufficiently powerful to unite, successively, by its attraction, all the others around its centre,
the ring of vapor will have thus become transformed into only one spheroidal mass of vapors,
circulating around the sun with a rotation in the same direction as its revolution. Now, if
we follow the changes which further cooling ought to produce in the vapory planets, of whose
formation we have just spoken, we shall see grow up in the centre of each of them, a nucleus,
incessantly increasing by the condensation of the atmosphere which surrounds it. In this con-
dition, the planet resembles perfectly the sun in the nebulous state, in which we have just been
considering it ; the cooling ought, then, to produce., at different limits of its atmosphere,
phenomena similar to those we have described ; namely, rings and satellites circulating around
its centre, in the direction of its motion of rotation, and turning on their axes in the same
direction." — Systeme du Monde. Paris edition: pp. 467-468.
This great theory of Laplace, called his nebular theory, appears to be looked upon by astron-
omers with wonder, almost with awe, and as a thing which they may scarcely dare to touch. It
is regarded with favor, yet there are few cosmologists who venture a decided opinion upon it ;
and, indeed, while there are few points from which it can be controverted, Laplace himself
seems to have exhausted what can be said in its favor, in the few lines which he has given to it,
in a manner far from positive, and in a retired corner of his book. If that theory be true, however,
we have reason to think that no one of the planets may have absorbed in itself all the nebulous
matter of the ring from which it was originally formed ; and that, consequently, there may be,
to each of them, a remainder substance, in the form of a ring, or rings, with the planet for its
centre. In the case of Saturn, such rings are visible by the aid of our glasses. To Jupiter,
such rings have given four satellites ; for our own globe, one satellite has been produced. And
we may well query, whether there may not be still a remainder of the nebulous matter left from
the ring originally producing the earth ; the nebulous substance of that ring not having been
all exhausted in the formation of our earth and its moon, and showing itself in a ring such as
we are now considering.
But, avoiding any consideration of these topics, as regards other planets, and confining our-
selves simply to the facts of the Zodiacal Light, and of a ring central to the earth, to which
they seem to lead us, we proceed to apply the results of Bouguer's experiments to this case.
In the annexed diagram, constructed according to this supposition,* the observation quoted
in the former sections — that of September 4th, 1853 — is again taken as an example, and for the
same reason ; namely, that it is a simple one, and one also in which the spectator is near the
plane of the ecliptic. The horizons, at 4h 30'", 3h 30m, 2" 30m, lh 30m, and at midnight, are
given, together with the lines of the spectator's vertices, as well as his positions, o o, &c., at
4" 30m and 3" 30m, &c. A B F C are the boundaries of the Zodiacal Light at 4" 30m, and
° The relative proportions of the earth and the ring, and also its distance, are, of jourse, not given in this diagram
with any effort at certainty ; the upward extent of the ring is probably far greater than can he here represented. The
diagram is, however, sufficiently correct for our present purposes of elucidation.
XXVIII
INTRODUCTION.
E F G at 3h 30m ; the apices C and G are carried a little above the more condensed portion of
the ring ; but the reader is at liberty to suppose them to be at any other part, as he may think
best. The direction of the sun is given; and S', S", S'", S"", S""', are supposed to be rays of
light proceeding from that luminary.
NEBULOUS RING, WITH THE EAKTH FOE ITS CENTRE.
In this diagram, the sun's rays being S', S", &c., B 0, F 0, &c., will be the reflected rays;
and the several angles between these lines of incidence and reflection, together with the num-
ber of rays reflected to the eye, out of every 1,000 incident rays, according to Bouguer, are in
the following table :
INTRODUCTION.
XXIX
Alible.
Rays reflected from smooth
water.
Kay-; ictl' ci-'tl I'mm pl;it<--
glass not quicksilvered.
S', BO 161°
343
422
S" F 0 146°
184
270
S'" D 0 131°
101
102
S"", HO 116°
59
105
S'"", at midnight, 90°
S CO... . 67°
18
18
25
25
Still acknowledging that we know not what nebulous matter is, and therefore that we cannot,
with certainty, argue about its properties of reflection; yet still claiming as a high probability,
amounting almost to certainty, that the laws of reflection, applying to all other bodies, to
solids, to vapors, to the molecules of our atmosphere, apply also to nebulous matter, we find in
the above table a strong argument for such a ring around the earth. The figures, taking either
of the two columns, for water or for glass, correspond in a very striking degree with the
van-in"1 intensity of the Zodiacal Light, from the base upward, as we have it on any clear
mornino- Or evening when the ecliptic is at a high angle with the horizon, and when, conse-
quently, the nebulous figure is not brought angularly to our eye. They also correspond to
what is, indeed, almost synonymous with that which has just been stated — namely, to the fact,
that at 4'' 30m, the Zodiacal Light at the horizon is far greater at its base than it is at
3" 30m; at 3" 30m, than it is at 2" 30™, &c., back to midnight. Any person, who has ever
looked attentively at this Light, when making a high angle with his horizon, will see at once
the coincidence between the proportions in the above figures, showing the number of reflected
rays, and what has been always presented to his eye. If the reader will also carry these lines
of incident and reflected light beyond the midnight horizon-line, to any point there of the
nebulous ring, he will see how we may easily get what is referred to in my charts under the
German name of gegenschein — i. e. a dim light, seen, when the circumstances are favorable for
it, in those portions of the sky opposed to the sun. This hypothesis shows also, very clearly, how
I could have the Zodiacal Light above both horizons at the midnight hours, as I was often able
to do, and it harmonizes fully with the strength of the Light as then presented to the eye.
Indeed, while Bouguer's results are antagonistic to all the theories discussed in the previous
sections, and seem to be utterly irreconcilable with them, they fully coincide with this, in every
one of its aspects ; and, so far as they can go, they satisfy the mind, in all the varying characters
of the Zodiacal Light.
I said, so far as they can go ; for there are points in this subject, such as the pulsations
of light, and what in the annotations to these charts is called the " effulgent light," which
belong to something in the nebulous matter which we have not yet fairly reached, and which
must be left for explanation to yet further observations.
While there are some things still left unexplained, I have, yet, not been able to see any thing
in this hypothesis antagonistic to the facts of the Zodiacal Light. On the contrary, almost all
of them are explained by it; and they all, as far as I can perceive, fully harmonize with it,
through the whole of the manifold changes which the light underwent, either from the changes
of the ecliptic towards any fixed spot, or from my numerous and great changes of latitude
during our cruise. But, for this, I must refer the reader to the charts and annotations of this
hunk. In examining them in detail, we must n'!ii<'inbf>r the deduction just drawn in § I, from
XXX INTRODUCTION.
the general mass of data — namely, that as the spectator's place is changed relatively to different
portions of the nebulous ring, such portions change, for him, their reflected light ; just as is done
every day, to our eye, by clouds or other terrestrial objects. Remembering this, he will, I
think, fully understand why, when I was on the northern .side of the ecliptic — i. e. towards the
northern edge of the ring — its reflection was chiefly on that side ; why its southern portions gave
me the chief reflection when I was towards its southern side ; and so, why all the various aspects
detailed in Nos. 1, 2, 3, 4, and 5, of § I, were, at different hours or seasons, presented to my
eye.
If it should be objected to my deductions from Bouguer's law of reflection, that the intensity
of light, which his results would give this ring when brought between our eye and the sun,
ought to make the ring a very striking object to us during a total eclipse of the sun; I reply,
that the increased intensity of the Zodiacal Light, from the apex to base, is a fact independent
of any theories; that, on any supposition of causes, it can scarcely be doubted that this reflec-
tion, so increasing from apex to base at the horizon, goes on still increasing in force below the
horizon, towards the direct line between our eye and the sun; and that, consequently, if the
Zodiacal Light is not a striking object in a total eclipse, stretching off from each side of the sun,
this fact is not more against the hypothesis of a ring around our earth, than against a ring
around the sun or in any other place. As respects such eclipses, however, if the observer of
them is in a high latitude, north or south, he will, except at only one portion of the year, have
the ecliptic at a very low angle with his horizon (even, under the best circumstances, not at a
high angle), and therefore cannot expect to have a good exhibition of the Zodiacal Light at
the time of eclipse. There was, however, an observation made in Peru, during a total eclipse,
on the 30th of November, 1853, from which we might expect something of a more decisive
character. The observer was Professor Carlos Moesta, of the Observatory of Santiago, who, at
the suggestion of Lieutenant Gillis, U. S. N., was sent to Peru, by the government of Chili,
for that purpose, and who afterwards made a highly interesting and valuable report to the
Minister of Public Instruction, with a sketch of the heavens as they appeared at the time of
the total obscuration of the sun. His place of observation was in lat. 14° 21' 21" S., and con-
sequently he had the ecliptic at a high angle with his horizon: the sun at that time having a
declination of 24° 42' S. — i. e. 7° 21' south of the observer. Every thing was favorable, as re-
gards an observation for the Zodiacal Light, on that occasion ; and we have, in his engraved
plate, in addition to the corona usual in total eclipses, a long ray projecting from the sun S.
70° E., and another, also a prominent and striking object, but not quite so long, stretching
off N. 80° W. He says : "Nearly all the northern part of the ring [corona] was uniform ; the
opposite side was evidently composed of numerous rays, which appeared to come from the ring,
and all which had the same length, with the. exception of two very large ones. Of these last,
one was in an upward direction, and inclined about 20° S. of E., and according to estimation,
its upward extent is as large as a diameter of the moon ; the other extended from the ring
downward, not diametrically opposite to the former, but inclined about 10° N. of W., and was
a little shorter than the other. The appearance of these two rays was much like that of a
cornet, narrower at the end than near the nucleus, and clearly radiating in its structure; since
it could be seen, perfectly well, that these rays were not of a homogeneous light, but composed
of a vast number of very small rays. Soon after the eclipse I made the annexed sketch, in
which I have endeavored to represent this ring [corona] as nearly like the original as possible."
It should be added to this, that Mr. Moesta's drawing was from a view through the telescope;
INTRODUCTION. XXXI
I have, myself, .always found the naked eye Letter for viewing the Zodiacal Light than telescopes.
Through our ship's glasses I was never able to see it at all.
If we could have a Zodiacal Light ol'an undoubted character produced hy the full moon, not
only would the question before us be set at rest, but the ring would lie shown to be within the
orbit of the moon ; and how near we came to a case of that kind on the evening of February 14*,
1854, the reader will decide for himself. There was no subject connected with these observa-
tions, in which I was so carefully watchful ; but, in summer, the moon, when full, must rise
long before the crepuscule ceases, and it is only in winter months that satisfactory observations
of this nature can be made ; and in the few instances of this kind which offered, clouds inter-
fered to prevent them.
For myself, I have no doubt that what I saw, in all the cases given in these charts, was really
Zodiacal I/igJut produced by the moon. When the equator and ecliptic were furthest removed
from each other, the Light still kept closely with the ecliptic, and, therefore, could not have been
atmospheric; and the boundaries, though only in one case having the altitude of the sun's
Zodiacal Light, still, as far as they ascended, always resembled fully those produced by the sun.
From the deductions made in § I, it is apparent that we cannot expect to get a parallax of this
ring; and that we can hope for only approximations to its width. In the morning observations
Nos. 137, 145, 15*7, 159, I appear to have got the full lateral extent northward of the Stronger
Light, about 30° ; and in No. 130, of the Diffuse Light 45° ; but the evening observations of
June, July, and August, 1853, differ somewhat from these. The inference from the whole of
these data would seem to be about 60° for the full width of the Stronger, and 90° for that of the
Diffuse Light.
I endeavored to have simultaneous observations made in Connecticut while I was in the extreme
southern latitudes, but did not succeed.
§XI.
This ring must, according to the laws of matter, rotate on its centre ; and it seems to be full of
commotions within itself. The existence of the pulsations, so often referred to in this book, seems
scarcely to admit of a doubt, recorded as they have been by observers in such distant quarters
of the globe. They were, as a general thing, very obscurely marked; but at times they
appeared to be so decided that I had no longer a doubt of their reality. They could scarcely
be owing to irregularities on the surface ; for the changes appear to have been too rapid and
extensive for such a cause. But that is possible. The following, respecting the rings of Saturn,
is from Laplace's Mecaniqiie Celeste: "Hence it follows that the separate rings which sur-
round the body of Saturn, are irregular solids, of unequal width in the different parts of their
circumferences ; so that their centres of gravity do not coincide with their centres of figure.
These centres of gravity may be considered as so many satellites, which move about the centre
of Saturn, at distances depending on the irregularities of the parts of each ring, and with
velocities of rotation equal to those of their respective rings." — Bowditch's Tr., vol. v, p. 5 1C.
If we allow an irregularity of width to the earth's ring, it may account for the changes in
its intensity of light; the Zodiacal Light this spring (1856) having been considered as of much
greater brightness than in previous years.
s The moon was full at Greenwich February 12, 14A. 5(!m. ; allowing for the cliU'iTrmv in longitude, the observation was
lil. (Jh. i'Jin. after the full ; flic next evening's observation, with still more decided results, was 2d. Th. 28)K. after the full.
XXXII INTRODUCTION.
§XII.
If this nebulous matter gives us its reflected light only from certain portions of it — i. e. only
from portions in position for admitting such reflection to our eye, as seems to he shown in § I —
may not the light from the tails of comets* (query: portions of very elliptic rings, the plane of
the rings then coinciding with our eye?) he given and withdrawn in the same manner; so that,
instead of such appendages suddenly shot out, and as suddenly withdrawn or dissipated, and at
times, contrary to all laws of dynamics, preceding the body from which it emanates, we have,
more philosophically, a substance always permanent, but giving its light to our eye only in
certain portions of its orbit?
In conclusion, I wish here to express my acknowledgments for indulgences and kindnesses
often received from the officers of the United States frigates "Mississippi" and "Macedonian,"
while in the prosecution of my work; especially from Captain S. S. Lee, of the former, and
from the late Commodore Abbot, of the latter ship. I owe, still more, my most hearty thanks
to Commodore Perry, who never failed to encourage others in useful efforts, while himself lead-
ing successfully in an honorable and glorious enterprise.
GEORGE JONES.
BROOKLYN, NEW YORK, May 26, 1856.
° "The tail of the great comet of 1680, immediately after its perihelion passage, was found by Newton to have been no
less than 20,000,000 of leagues in length, and to have occupied only two days in its emission from the comet's body ; a
decisive proof, this, of its being darted forth by some active force, the origin of which, to judge from the diameter of the
tail, must be sought in the sun itself." — Sir J. Herschdl's Outlines of Astronomy.
INTRODUCTION. XXXIII
As this book may come into the hands of foreign astronomers, to whom the author's name
will be new, and who may wish for some introduction and vouchers for reliability, he offers the
following letters — written, however, for another purpose — -but which he has still the writers'
permission to print :
CAMBRIDGE, MASSACHUSETTS, July 5, 1855.
DEAR SIR: We have examined with great interest the valuable results of your observations
upon the Zodiacal Light during your cruise with Commodore Perry's expedition, and have much
pleasure in being able to bear our testimony to the importance of these observations. From .
even the superficial examination which the nature of the case permits, we have been strongly
impressed with the richness of the materials for thorough and successful study of the Zodiacal
Light, which have been collected by your unwearied zeal, applied under peculiarly favorable
circumstances.
There can be no doubt that a careful study of your charts will develop new and important
facts ; and we consider it of the highest importance that the complete series may be published,
without abridgment, and thus rendered accessible to all who may wish to pursue the study of
the curious phenomena which you have so diligently and successfully observed.
We are, dear sir, with much respect, your friends and servants,
(Signed) BENJAMIN PEIECE,
[Perkins Prof, of Astronomy and Mathematics, Harvard University.]
B. A. GOULD,
[U. R. Coast Survey, editor of Amer. Astronomical Journal.]
Rev. GEO. JONE?, Chaplain United States Navy.
YALE COLLEGE, NEW HAVEN, CONN., May, 1855.
The undersigned have seen, and examined in part, the charts and observations on the Zodi-
acal Light made by Rev. George Jones, while under your command, in the Japan expedition.
In our estimation, they are rich, various, reliable, and of great value. They relate to a
grand subject, embraced in the discussions and inquiries concerning the constitution of the Solar
System at least, if not of the universe. Independently of any views or theories respecting the
actual origin of the Lights, and the phenomena observed by Mr. Jones, with such rare oppor-
tunities and diligence, we give it as our opinion that a full publication of the charts and obser-
vations will enrich physical science, and add to the lustre of the expedition, and the enduring
worth of its history.
(Signed) B. SILLLMAN, SEN.,
[Emeritus Prof, of Chemistry, Geology, &c.]
JAMES D. DANA,
[Professor of Natural History.]
DENISON OLMSTED,
[Prof, of Nat. Philosophy and Astronomy.]
W. A. NORTON,
[Professor of Civil Engineering.]
EDWARD C. HERRICK,
[Librarian.]
ALEX. C. TWINING,
[Lute Prof. Xat. Phil, and Math, in Mirldlebury College.]
Commodore M. C. PERRY,
Commander of the Japan Expedition.
25
XXXIV INTRODUCTION.
UNITED STATES NAVAL ACADEMY,
Annapolis, Maryland, June 21, 1855.
MY DEAR SIR: What I Lave already seen of your remarks on the Zodiacal Light, makes me
extremely desirous of seeing the whole. I hope all your observations will be published, with
the utmost detail. We have heretofore had but few accurate observations on this Light.
Vague and general descriptions, by different observers, at distant periods of time, without the
aid of diagrams, except in very few instances, are all that we possess. The exact outline pre-
sented by the Light, from day to day, and its position in the heavens, as determined by the
stars near which the outline passes, are obviously indispensable in prosecuting research on it.
Your drawings (if published just as you made them on the spot, with the phenomena before
you), will supply these desiderata, and astronomers will be put in a position to judge, as they
might have done, had they enjoyed the same rare opportunities which you not only enjoyed, bat
so industriously improved. Not a single observation should be omitted, nor should any mere
abstract be made in lieu of a complete publication. We want the facts just as they are, and as
they will be shown by your faithful charts.
Whatever theories may be held with respect to this Light, the publication of your series oi
observations will be a most important contribution to science, if it will not, in fact, furnish the
means of deciding one of the questions of astronomy heretofore most obscure.
Very respectfully, yours,
WILLIAM CHAUVENET,
[Prof, of Astronomy, &c., in the U. S. Naval Academy.]
Rev. GEORGE JONES, United States Navy.
INTRODUCTION.
XXXV
Index of Times, Latitudes, &c.
No.
Date of obser-
vation.
Latitude.
].i<li!!i!lldC.*
\VJicn taken.
Where taken.
Remarks.
1
1S53.
April 2
o '
10 32 N
O '
110 9 E
4
16 i4
110 3l>
do
do
" 5
IS 51
lit 4S
do
do
4
" 6
•!\ ->'l
112 51
do
" 7
•>•' is
114 10
(j
" 8
22 18
114 10
do
do. . - do
7
" 9
•'•' IS
114 10
do
.... do - - do
g
" 26
2'> 11
113 36
do
9
" 99
23 55
118 38
do
26 10
127 42
do
11
" 8
2H 10
127 42
do
do. - do
19
" 11
26 10
1»7 42
do do
13
" 15
26 10
127 42
do
do . do» .
" 23
26 10
127 42
I ^
" 24
26 10
127 42
do
1 fi
" 25
'' (i 1 II
r>~ 4''
do
.do do
17
" 27
26 10
r>7 4*
do
do do
18
'• 29
26 10
127 42
do
_do_ _ _ . do
1 Q
" 30
26 10
1''7 4''
do
on
Tulv 1
26 10
1'7 42
do
21
" 2
26 10
do
At sea
29
" 4
29 9
131 -'S
do
do -
9 3
" 5
29 36
132 5
do
94
" 5
30 47
133 3.">
Evening
._ do .
9K
" • 6
31 8
134 31
do
26
'• 6
32 13
136 34
do
27
7
32 36
137 26
.do
Also East Zodiacal Light.
28
" 7
33 50
138 53
do
[in the evening.
90
" 8
35 12
139 44
do
Off Uraga Bay of Yedo Japan
30 !
" 9
35 12
139 44 -j
Morning . i
do do _
31 S
32
" 9
35 12
139 44
Evening - j
do
do . - - . . do .-
East Zodiacal Lisfht in
33 I
" 11
35 12
139 44 -j
Morning . |
do do
[the evening.
. 34 f
35
" 13
35 12
139 44
Evening . j
do do
36
" 14
35 23
139 41
do
Upper Bay of Yedo
37
" 15
35 23
139 41
do
do do
38
" 16
35 23
139 41
do
do do
39
" 18
33 42
138 13
do
40
" 19
32 4
135 55
do
___do
41
21 45
I'l 33
do
42
" 5
21 31
121 3
do .
Also East Zodiacal Light
43
" 16
23 2
113 28
do
Blenheim Reach, Canton river-
_ . . [in the evening.
44
" 17
23 2
113 28
do
do do
45
" 26
23 2
113 28
do do
46
" 29
23 2
113 28
do
do do
47
" 31
23 2
113 28
do
do . . do
48
Sept'r 1
23 2
113 28
do
. do do
49
" 2
23 2
113 28
do do
50 !
" 3
OQ 9
113 28 \
do I
51 i
52
" 5
23 2
113 28
Evening _ f
Morning
do do
53
" 12
23 2
113 28
do
_do do
54
" 13
23 2
113 28
do
55
" 14
23 2
113 28
do
do do.. - -
56
" 15
23 2
113 28
do
do _ . .do
57
" 24
23 2
113 28
Evening
. _do. do
* 58
" 27
23 2
113 28
.do-
_ do do
59
" 28
23 2
113 28
do
60 )
" 30
22 23
113 32 1
Morning . J
61 1
62 I
i
22 23
113 32 \
Evening _ j
Morning _ |
.do . do
e
63 j
64 j
" 3
22 23
113 32 \
Evening . j
Morning - }
65 j
Evening - j
* The longitudes, of course, can have no influence on the Zodiacal Light ; but I have thought that it might interest the reader to know in what part of
the globe the observations were made.
XXXVI
INTRODUCTION.
INDEX— Continued.
No.
Date of obser-
vation.
La itude.
Longitude.
When taken.
Where taken. Remarks.
66
67
68
69
70
71
329
72
330
73
74
75)
76 f
77 |_
78 j
79 1
80 j
81
82
83
84
85
86
87
88
89
90 )
91 r
92 )
93 f
94
95 1
96 j
97 )
98 f
95
100
101
102
103
104
105
106
107
108 )
109 \
110 |
111
112
113
114
115
116
331
117
332
118
333
119
334
120
122
123
124
125
126
197
1853.
October 4
8
" 18
" 19
" 20
" 21
" 21
" 22
" 22
" 27
" 28
" ' 29
" 31
Nov'r 1
2
3
4
5
8
" 22
Dec'r 5
" 21
•' 28
" 29
" 30
" 31
1854.
January 2
3
4
5
6
" 10
" 11
" 18
" 24
" 25
" 26
" 27
" 30
" 31
" 31
Febr'y 1
2
4
" 14
" 15
" 15
" 17
" 17
" 18
" 18
" 20
" 21
" 23
" 24
" 25
March 6
7
" IS
O '
22 23 N.
22 11
22 11
22 11
22 11
22 11
22 11
22 23
22 2:;
22 23
22 23
22 23
22 23
22 23
22 •.'.•;
22 23
22 23
22 23
22 2.'!
22 IS
22 18
23 4
22 18
22 18
22 18
22 18
22 18
22 18
22 18
22 18
22 18
22 18
22 18
23 40
26 10
26 10
26 10
26 10
26 10
26 10
26 30
26 30
26 45
2fi 33
35 19
35 19
35 19
35 19
35 19
35 19
35 in
35 19
35 19
3.i 19
35 25
:;:• 2:.
35 26
35 26
35 26
O '
113 32 E.
11. -i :;r,
113 36
113 36
113 36
113 36
113 36
113 32
113 32
113 32
113 32
113 32
113 32 |
113 32
113 32
113 :;2
113 32
113 32
113 32
114 10
114 10
113 26
114 10
114 10 \
114 10
114 10
114 10
114 10
114 10
114 10
114 10
114 10
114 10
123 28
127 42
127 42
127 42
127 42
127 42
127 42
127 45
127 45
127 45
127 54
139 43
1.39 43
139 43
139 43
139 43
139 43
139 43
139 43
139 43
139 43
139 41
139 41
139 42
139 42
139 42
Horning
do
Ouni^iiicrniooD Oil inn,
do - -
do
do
do
do
do
do
do
do
Moon Zodiacal Light —
do
.do. ...
do , _do_
Moon Zodiacal Light —
do
do do
do
Morning . [
Evening . )
Morning . \_
Evening - f
Morning - )
Evening . j
do do
do . do L
do
do
Evening
do
Evening
do
Wlmmpoa Reach, Canton river-
Morning . )
Evening . (
Morning . I
Evening . j
Jo
do
do
do 1
do
Evening . j
Morning . I
Evening - j
do
do
do
do -
do
do -
do
do
do
do
Evening —
do
do
do
Morning . 1
Evening . j
Morning . 1
Evening . )
do do
r ' S
,.
do
do
do
do
do
Evening —
Hn
Moon Zodiacal Light —
do
do . do
Moon Zodiacal Light —
do
do do. -
do
do do
Moon Zodiacal Light
do
do
do
do do 1 Moon Zodiacal Light
fin
do do
do
do
do
r dO
Off Yokahama, Bay of Yedo . . .
Joint sun and moon
Evening . . - -do. . . . -do. .
INTRODUCTION.
INDEX— Continued.
XXXVII
Nn.
Date of obser-
vation.
Latitude.
Longitude.
When t;iken.
Where taken.
Remarks.
335
128
1854.
March 18
" 20
o '
35 26 N.
35 26
o '
l.J!!> 12 E.
Ki9 I''
Evening —
. do
Off Yokahama, Bay of Yedo
__ do do
Moon Zodiacal Light
336
" 21
35 ''6
l.'!9 12
1''9
" 25
35 26
139 42
130 |
" 27
35 26
139 42 -j
Morning - |
131 j
132 J
" 28
35 26
139 42
Evening . j
Morning . j
133 j
134 J
" 21
35 26
139 42 \
Lvrning - f
Morning . j
135 f
136
" 30
35 26
l.'i'i (•'
Evening . j
do
137
April 1
35 26
i::9 i:i
do do .
1 '{S
" 17
35 19
l'!9 4 '5
337
" 17
35 19
139 43
do
do do
1 M9
" 18
34 40
r;-; vi
do
140
" 20
34 40
138 59
do
141
" 21
31 40
138 59
do
142
" 22
34 40
138 59
do _ - do .
143
" 24
34 40
i:;s .vi
do - do
144
" 25
34 40
138 59
do
1 i :. /
" 26
34 40
138 59 •!
Morning - )
do . do..
148 j
147
" 27
34 40
138 59
Evening . )
do -do
148
" 28
34 40
138 59
do do
149
" 29
34 40
138 59
do
150
May 6
34 40
138 59
151
" 8
34 40
138 59
do
do do
1 ^9
1 1 i .->
40 13
142 52
338
" 15
40 31
142 59
do
do
Moon Zodiacal Light
153
" 16
41 50
141 OS
do
do
1 ^1
" 17
41 49
140 47
do
1 KK
" 19
41 49
140 47
do
do
1 ^fi
" 20
41 49
140 47
do
do
157 )
" 22
41 49
140 47 -j
Morning . )
do
158 f
1 w
" 23
41 49
140 47
Evening . j
do
1(10 I
do 1
do
n;i \
1 H9
" 30
41 49
140 47
Evening . f
do
163
41 49
140 47
do
do
" 5
37 34
141 59
do
1 c^
" 8
34 40
138 59
do
166
" 21
34 40
138 59
Evening
do
167
" 22
34 40
138 59
do
do
1 KS
" 24
34 40
I'iS .VI
do
do
it 97
33 01
1'3G 45
do
" 29
30 26
136 52
" 29
28 33
136 21
" 30
28 22
138 18
do do
Tnlv 1
27 35
136 08
do
do . do
174
" 4
28 51
132 00
do
... __do do
1 7^
" 5
29 50
130 49
do
" 6
29 18
129 37
do
do do
" 7
28 56
127 52
do
do do
178
" 8
91) H
12fi 26
do
do _ do
" 13
25 09
121 46
1 on
" 14
25 09
121 46
do
339
" 14
" 1 ^
25 09
25 09
121 46
r'i 46
do
do
do do
Moon Zodiacal Light
1 00
" 18
25 09
1 '' 1 46
[ do
1QO
" 19
25 09
r>i 46
do
do do -
1QJ.
" 20
95 09
191 46
do
do do
IOC
" 91
25 09
l''l 46
do
" 92
25 09
I'M hi
do
do do - _ .
« 9.[
95 39
r>i 37
" 24
25 38
120 39
do
(i 9K
25 31
190 41
do
ion
11 25
25 00
120 28
do .
mi
" 2fi
24 24
120 04
Morning - .
...do..,
XXXVIII
INTRODUCTION.
INDEX — Continued.
No.
Date of obser-
vation.
Latitude.
Longitude.
When taken.
Where taken.
Remarks.
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
340
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
1854.
July 29
" 31
August 1
4
" 12
" 17
" 18
" 21
" 21
" 22
" 22
" 23
" 23
" 24
" 25
" 26
" 28
" 29
" 31
Sepfr 4
" 12
" 12
" 13
" 14
" 16
" 19
" 20
" 20
" 21
" 23
" 27
" 28
" 30
Octo'r 11
" 12
" 14
" Ifi
" 16
" 16
" 17
" 18
" 20
" 21
" 21
" 23
" 25
" 30
Nov'r 1
" 11
" 13
" 20
" 20
" 21
" 22
" 25
" 27
" 28
" 29
Dec'r 7
8
9
" 11
" 12
" 13
" 15
" 16
" 18
" 18
" 19
" 19
O '
20 41 N.
19 29
18 35
17 48
14 36
14 19
14 22
14 27
14 44
14 46
15 45
16 00
17 59
18 36
20 47
21 00
22 18
22 18
22 18
22 18
22 15
22 14
23 04
24 o;.
27 31
29 5(5
32 06
33 27
33 54
34 40
34 40
34 40
34 40
35 24
35 33
33 46
33 16
33 16
33 01
31 52
30 41
28 05
25 58
24 49
21 18
21 18
21 18
21 18
23 52
26 31
36 17
36 54
37 16
37 48
38 02
38 02
38 02
38 02
38 02
38 02
38 02
38 02
38 02
37 48
37 48
37 21
33 58
31 43
31 02
29 39
O '
114 54 E.
116 22
119 32
116 31
121 02
120 40
119 52
Morning
do
do •
do
rln
do. - do _. _J
Evening
do
do
do
117 16
117 12
117 11
116 36
116 26
115 42
115 26
114 32
114 18
114 10
114 10
114 10
114 10
115 04
115 18
116 47
lls II
124 23
i:;i :;i
135 08
137 40
138 01
138 58
138 58
138 58
138 58
165 16
169 18
175 52
178 21 W.
177 28
174 49
171 28
167 45
164 24
161 58
160 41
157 55
157 55
157 55
157 55
152 34
147 27
126 51
125 00
123 33
122 21
122 07
122 07
122 07
122 07
122 07
122 07
122 07
122 07
122 07
122 21
122 21
122 45
120 26
120 03
119 23
117 20
Morning
do
do !
do .
do -
Mornin0"
dn
do -
do
do
do
do
do do
do
do do
do
do do . .
Evening —
do
Moon Zodiacal Light —
do
do do
do
do do
do
. do __do L
Morning
__do -__do -.
do
do do ...
do do.
Evening —
do
do
do ...
do
Evening
do
do
do
do
do
do
Morning
..do..
(
-j Duplicate day
do
do
Morning -
do
do
do
do
do
Honolulu Sandwich Islands __
.do
do ..do
do
do do
Evening —
do
do
Morning
do
do
do
do
do
Evening
Morning —
do
do
do
do
do
do
do
do
do - ..
-do
do -
do
do
do
do '
do
San Francisco
do
do
do
do
do - .
do
Kvrllinff -
..do..
INTRODUCTION.
INDEX— Continued.
XXXIX
No.
Date of obser-
vation.
Latitude.
Longitude.
When taken.
Where taken.
Remarks.
261
1854,
Dcc'r 20
O '
28 50 N
O '
111! 13 W
•'li ."ll
115 ''"
do
263
21
11 1 4S
do
23 16
ll9 20
do
do
265
ll 99
•'1 4ll
110 39
do -
17 •'!
103 17
do
9||7
" ' >
16 31
100 24
do
268
" 26
15 59
100 24
do
9l'>'l
" 28
13 18
94 44
do
do
•'711
11 38
92 03
do
do
•'71
" 30
111 111
89 31
do
do - -
979
1855.
7 27
S5 39
do
do -
273
5
8 47
79 31
Evening •
Taboga, Bay of Panama
274
" 6
8 47
79 31
do
275
" 8
8 47
79 31
do
do do
276
" 9
8 47
79 31
do
977
" 111
8 47
79 31
do
do do
278
" 11
8 47
79 31
do
do do
279
" 12
7 07
79 26
do
At sea . _
•'-n
" 15
21
80 37
do
do
281
" 17
9 54 S
si ;.:>
do
do
" Is
3 40
s-' 20
do
283
" 18
5 07
82 14
do -
284
" I'l
81 52
do
285
" 90
9 52
SO 33
do
"
286
" 22
79 28
do
287
" 23-
14 44
78 51
do
do -
288
" 30
29 07
72 49
-do
.. do
341
Feb'y 3
33 01
71 41
289
G
33 01
71 41
do
.do
290
" 7
33 01
71 41
do
do
291
" 8
33 01
71 41
do
do
292
" 9
33 01
71 41
do
do
293
" 12
35 41
73 59
do
At sea .
294
" 19
51 57
75 5S
do
_ .do -
•"1 "i
ii 91
53 38
70 53
do
296
ll 92
53 38
70 53
do . -
297
" 23
52 28
67 29
do
At sea -. ..
'98
" 28
40 51
57 21
do
do
'99
March 1
39 11
57 12
.do
300
" 13
22 55
43 06
301
" 15
22 55
13 06
do
do do
302 I
" 16
22 55
43 (Hi -1
Morning - )
do do
303 1
304 1
" 17
22 55
43 06
Evening - \
Morning - /
do do
305 j
306
" 20
22 55
43 06
Evening . )
..do .. . do - _ -
307 )
do . )
" 21
9 2 55
43 06 •!
do do_..-_
309
" 23
•'2 55
i:) (it;
Evening - )
Morning
__ do - do.
310
" 24
22 55
i.1; in;
..do
. . _do . - -do
311
" 96
22 08
39 26
do
312
" 28
19 32
36 13
do
do
313
.1 9.)
17 24
35 10
do- ---
do
314
\jiril 1
1 37 X.
37 37
Evening - .
...do
315
" 9
11 1'
15 51
do
do
316
" 10
13 05
47 20
do
do
317
•• 11
15 (I'.l
is .Mi
do
...do ,
318
13
]S (15
51 25
Mm ning
...do
" 13
20 09
53 19
do
320
14
20 59
5 I 09
do
:;•' 1
" 1 1
22 .'il
55 111
Evening
_ do
322
" 16
25 28
59 19
M' Tiling _ . .
do _-.... ....
i :
323
' 16
27 04
61 35
do
324
' 17
27 59
62 26
--do - ...
325
' 18
30 30
...do
326
' 18
32 10
67 16
Evening
...do
327
' 19
33 12
68 16
do
328
' 21
37 38
73 09
do
do
INTRODUCTION.
Cassini's Oltservatiom.
No.
Date of observation .
Latitude.
Longitude.
\Vhrji taken.
342
1685.
Febru'y 27
O '
48 51 N
O '
2 22 W
343
March 22
48 51
2 22
do
344
April 21
48 51
2 22
do
345
Septem'r 9
48 51
2 22
Morning .
346
27
48 51
2 22
do
347
Novem'r 27
48 51
2 22
do
348
48 51
2 22
do
349
350
25
1687.
March 7
48 51
48 51
2 22
2 22
Evening
do
351
October 15
48 51
2 22
Morning »
352
48 51
2 22
do
INTRODUCTION. XLI
THE CHART.
When the publication of this work had been decided on, I tried, in company with a friend at
the head of one of our observatories, a variety of other star-charts, to see how they would answer
for the purpose ; and we finally came to the conclusion that my original plan — that is, on Mer-
cator's projection, with the ecliptic for the straight, or central, and guiding line — was the only
eligible one. I determined, however, to construct the chart anew; and, for the purposes of
greater correctness, procured from London an eighteen-inch globe by Maltby & Son, "manufac-
tured and published under the superintendence of the ' Society for the Diffusion of Useful
Knowledge' ;" and from this, but chiefly from the old globe, which I had so well proved, the
present charts are constructed. In preparing such charts, I had no other resort than globes ;
for, with few slight exceptions, the published tables of the positions of stars give only their
right ascensions and declinations; and to convert these, by calculations, into latitudes and
longitudes, would have required more time than I could afford. This method of constructing
the charts is sufficiently accurate for our purpose.
Indeed, I soon found that, in the publication of this work, where I had no choice of circum-
stances, any hope of perfect accuracy was not to be indulged; and I had to be satisfied with
doing the best that I could. The charts were cut on wood ; and its subsequent unequal shrink-
age, together with shrinkage in stereotyping, must be the excuse for some defects in the plates,
which the reader will discover, but which, I think, will not be found in any way to affect seri-
ously the results. As to the lines, themselves, of the Zodiacal Light, I did not leave one of
them to the risk of such mistakes as unfarniliarity with the subject might produce; but, after
the plain stereotype plates had been prepared, I drew every line on them myself, the boundaries
of the Zodiacal Light, horizons, zenith lines, &c.; and the engraver then following after, he
has, I believe, given them with entire fidelity. I can thus assert that, for attaining accuracy,
no pains-taking on my own part has been spared.
Any one, who attempts to construct a star-chart from published materials, will find many
difficulties in his way. Of seven or eight of the best authorities to which I referred, as to the
magnitudes of stars, no two were agreed; indeed, the discrepancies were so great, that the more
I consulted, even standard authorities, the more embarrassed and uncertain I became ; and I
finally came back to my old 9-inch globe, which I had so long and thoroughly tested, and on
the general accuracy of which I knew I could rely. In my charts, Bellatrix is, however, put
down, by some inadvertence, as a star of the first, instead of the second magnitude; No. 8 Ceti
has, from the same cause, a latitude less by 40" than it ought to have. Doubtless there are
many other defects in the charts, respecting which I can only say that I have done the best foi=
accuracy that my circumstances would allow. I trust, however, that none will be found of
sufficient importance to impair any one's confidence in the results here offered to the public.
The numbers given to the stars, when such are adduced, are those which I found on the 9-inch
globe.
2 6
XLII
INTRODUCTION.
THE LINES ON THE CHARTS, &c.
Represents the sun in its position at the time of observation.
Star of the first magnitude, 8 rays.
Star of the second magnitude, 7 rays.
Star of the third magnitude, 6 rays.
Star of the fourth magnitude, 5 rays.
Star of the fifth magnitude, 4 rays.
The central, straight line, up and down the page, is the ecliptic (consult chart No. 1), the
guiding line in these charts.- The scales of degrees, at the bottom and sides of the plate, are
those of latitudes and longitudes.
The upward line, curving about the ecliptic, is the equator. (See also chart No. 1.)
The lines across the plates, mostly towards the bottom
of the plate, either full, or composed of full lines and
dashes/ represent the spectator's horizon at the times
specified.
The line with dots, towards the top of the plate, shows the course of the spec-
tator's zenith during the observations, his zenith point at each observation being
noted. The object is to show his relative positions toward the ecliptic or plane of
the nebulous ring, during this period. Where there is but one observation, his
zenith is denoted by a dot with a circle around it ; the time also being specified.
The full lines which pass upward on (he chart, curve
ver and return again, are the boundaries of the
h-onijer Zodiacal Light, at the times noted with each.
i In some instances, the apex is omitted.
INTRODUCTION.
XLIII
condensed part.
The lines of dashes, drawn in the same general course
as (lie preceding, are the lines of a dimmer Light border-
ing the Stronger, as if from a more diffuse portion of
the nebulous matter lying beyond the central or more
It is called, in my notes, the Diffuse Light.
On some of the charts are zigzag lines, showing the
extent of a very effulgent light at the base of the
Stronger Light. Its boundaries, at the upper part, were
not very decidedly marked, yet sufficiently so to enable
me to get them with a good degree of reliability.
Still beyond the Diffuse Light, there was, on some oc-
casions, an appearance which seemed not to be exactly a
positive light, but rather as if the sky was paled, or was
a little less dark than beyond. The boundaries of this
are noted by dotted lines. I consider this, however, only as from the outmost and most attenu-
ated portion of the nebulous ring, now making itself visible, in consequence of the ring beino-
brought more laterally to the eye than before. Such dots are also sometimes used at the apex
of the lines for the Stronger Light, and mean, there, a light scarcely perceptible by the eye.
Lines of dashes and dots combined, represent the
boundaries of th^Zodiacal Light as showing itself deep
in the night, from about 11 o'clock till 1. This Light
was in appearance like the Diffuse Light in its dimmer
aspects, but had lower and narrower boundaries ; and I have chosen a distinct mark for it, in
order to prevent the confusion which I found would arise on my charts, when the Diffuse Light
itself appeared.
The full lines on the charts, with letters of the alphabet attached, are boundaries when the
Stronger Light was subject to pulsations, or risings and sinkings of the Light, as noted on the
opposite page.
When lines run into each other, us in No. 90 and passim, the common line must be considered
as belonging to both observations, as far as the horizon will admit.
Sometimes the charts are too small to admit the zenith points, or the sun. In that case,
their position is given in the annotations opposite.
In making out the horizon lines, &c., for Cassini's observations, I allowed, for the annual
precession of the equinoxes, 50J", or '2° 22' since 1G85.
The reader will easily make out the N. and 8. directions in these plates. In the evening
observations, North is at his right hand; in the morning, at his left.
The time used in these annotations is, uniformly, mean time. I had to take my reckoning
from the timepiece at the cabin door, which, especially in our rapid transitions E. or W., was
sometimes in error by a few minutes. But this was of little consequence. The relative periods
during the observations were of more importance, especially in noting the pulsations: and in
these I was very particular ; so that the relative periods may be fully depended upon.
OBSERVATIONS
ON THE
ZODIACAL LIGHT
2 OBSERVATIONS ON THE ZODIACAL LIGHT.
fit was my intention to have this series of published charts commence in June, 1853; l>ut thu singular sliding over of the Zodiacal Light, bodily,
as the night advanced, and also its great inclination to the ecliptic, as shown in these observations in April, have induced me to take them from the
rejected matter, and to give them insertion. The whole of May (being at the change of monsoons) was cloudy, and did not give me a single reli-
able observation.
From June 7th, the series goes on in unbroken order until our arrival at home.]
No. 1.
APRIL 2d, 1853 : EVENING.
Latitude 10° 32' N.: Longitude 1103 9' E.
Sun set Gh. l^m.
Stronger Light j J * jj"1' I Diffuse Light probably* at 6k. 48m.
It is beginning to be difficult to get the northern boundary of the Diffuse Light, in consequence of its being so near
the Milky Way. It is, however, I believe, correctly given in the chart. The horizon is now hazy almost every
evening, and the Zodiacal Light cannot be made out for four or five degrees above its line.
In the early part of the evening, the boundary of the Stronger Light was as marked in the chart at a a. When
I went out again, at I7h 15m, the light appeared to have changed, bodily, over to the left, and was, as far as I could
judge, after careful observation, at the boundary b b; by ^ 50m it seemed to have again changed, and it now appeared
to be bounded by thu line c c. I never before noticed any changes of this character.
a The exact time not noted in my records.
OBSERVATIONS ON THE ZODIACAL LIGHT.
(J3
S3
-
!
=
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 2.
APRIL 4th, 1853 (3d was Sunday) : EVENING.
Lat. 16° 54' N.: Lon. 110° 36' E.
Sun set 6h. 10m.
Stronger Light] ™' g^"1' j Diffuse, probably at 7A. 10m.
The upper end of the Diffuse portion of the Zodiacal Light is now lost in the Milky Way ; it is also so dim now,
that I find great difficulty in getting its boundaries. I thought again this evening that, as time passed, the
Stronger Light appeared to slide bodily over toward the south. I have given its boundaries as they seemed to be at
the times specified in the chart.
ATIONS ON THE ZODIACAL LIGHT.
OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 3.
APRIL 5th, 1853 : EVENING.
Lat. 18° 51' X. : Lon. 111° 16' E.
Sun set Gh. llm.
Stronger Light -{ 7 30 ^Diffuse, probably at 6/1. 50m.
The evening was favorable for observations. The Zodiacal Light began to show itself soon after 6h 39m. There
is now scarcely a doubt in my mind that the Stronger Light changes its place, bodily, during the evening. At first, at
6h 50m, it was bounded by the line a a a. When I went out again, to observe, at 7h lom, it had changed, and its
boundary was at b b b; at 7h 30m, it had brought its boundary to c c c; and at *ih 45m, to d d d. At 8, it had got
still further to the left, and was as given in the chart at e e e, its right border being about Saturn ; but at this last
observation the light was very dim. At 8 o'clock, and for some time previously, the Diffuse Light, over towards
Algol, had faded entirely away.
OBSERVATIONS ON THE ZODIACAL LIGHT.
•s
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 4.
APRIL 6th, 1853 : MORNING.
Lat 21° 22' N.: Lon. 112^ 57' E.
Sun rose 5h. 52m.
Diffuse Light at i o'clock.
Rose early. The Zodiacal Light already to be seen at 3h 10m, but was near the horizon. At 4h, it was high
enough to give a distinct outline; but I was baffled by numerous flitting cirri, and could not get boundaries of the
Stronger Light. That given, I believe may be fully depended on.
OBSERVATIONS ON THE ZODIACAL LIGHT.
10 OBSERVATIONS ON THE ZODIACAL LIGHT,
APRIL 7tli, 1853 : EVENING.
Lat, 22 is' X. Lon. 1H 10' E.
Sun si-'t (\li. lam.
Stronger and Diffuse Light at S o'clock.
Last evening cloudy; so also this morning. This evening I was prevented from observing till 8 o'clock. At
that time, the Zodiacal Light was partly obscured by a cloud; but I was able to get its outline. I thought, at one
time, that the Diffuse Light crossed the Milky Way, and made itself perceptible above — as high up as Castor and
Pollux; but on calling a quartermaster to look also, he could not make it out higher than the Jlilky Way; so I let
it pass.
OBSERVATIONS ON T11K ZODIACAL LIGHT.
11
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12 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 6.
APRIL 8th, 1853: EVENING.
Lat. 22° IS' N.: Lon. 1H° 10' E.
Sun set 67*. 14m.
Stronger Light \ I'1' 3JJOT' I Diffuse, 8h.
( ° (> )
Clouds in the morning;. This evening was cloudless, but rather hazy, and the observation was not entirely satis-
factory. I have put clown the Light as it appeared to me; but I cannot offer these lines as fully reliable.
OBSERVATIONS ON THE ZODIACAL LIGHT.
13
14 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 7.
APRIL 9th, 1S53 : EVENING.
Lat. 223 is'N.: Lon. 114'- 10' R.
Sun set fi/(. 14m.
Stronger Light j ^ ^'"' j- Diffuse. T/i. i:.m.
Clouds in the morning. This evening, just along the horizon, ha/,y: but otherwise a good night for observation.
In the early part of the evening, the outlines of the Stronger Light \verc at « « « : the I.) i if use is marked also on
the chart. Wishing to make this evening's observation a particularly caivl'nl cue, on account o!' this singular sliding
over of the light, I called two of the quartermasters,* separately, and asked them to tell me where the Stronger
Light was. without putting any leading questions to them, or telling them my object. The first replied: "It is
considerably brighter to the right of that star (Saturn) than it is to the left: that star is its left-hand limit. :
Oh! yes, sir, the principal partis on the right of it." (Saturn). The other, to my question where the brightest
part, was, replied: "Well, 1 fancy it's to the right of that star (Saturn). Yes; that's the brightest place, right
under that group of stars, ( Pleiades,) and to the right of that star" (Saturn). This was at ?" '20ra. At 7U 45" I
called them again, and also Dr. - — , and asked them separately. Dr. - - described the outlines in the sky,
and I drew them on the chart at b I It by his description. The two quartermasters gave the same boundary. It
corresponded also to my own views ol' the case.
HJi nil- nil ilicfii' on/liitrs n/rii/ In' full ij rt'liril on. I notice, also, that, as the evening advances, the Diffuse Light on
the right, of « Arietis, and so up, entirely disappears. I have thought so for several evenings; this evening it was
decidedly so.
[Brooklyn, May 'Jfi, IS.',!',. These lateral changes of the whole body ol' the Sinmger Zodiacal Light are very
remarkable. I cannot see any room Ibr mistake; as there might have been, had the Light been more inclined to the
horizon. But the horizon and ecliptic made nearly a right angle. My own change of place, as respects the ecliptic,
during the interval of observations, does not meet the case. The gn-al inclination or' the Light, to the ecliptic is also
noteworthy. This latter circumstance appears also in the observations of March 30th and 31st, 1S.">:J; on which
occasions, however, I noted only the Dilfusc Light.]
«> It may be well to say to lundsmrn. (hut quartermasters are among the highest petty officers in mir ships. They arc taken fivim the oldest and
most reliable among the seamen. In [mrt, nne, and at sea, two, uf them must always lie mi deck, day and night, on watch or other duty.
OBSERVATIONS ON THE ZODIACAL LIGHT.
15
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OBSERVATIONS ON THE ZODIACAL LIGHT.
No. R.
APRIL 2Cth, 1S5.T : KYEXIXO.
Lat. 22° 11' N. : Lon. 113° Sl>' E.
Sun set fi/i. •_'•.'/«.
Diffuse Liglit nl s/,
We have much clomly weather now, owing to the change oi' monsoons. Hail an observation on the evening of the
llth, hut the Zodiacal Liglit was so faint that I have not thought it Lest to give a distinct chart for it. The moon
also interfered that evening till at S'1 10ra, when it got into a fog-Lank near the horizon; at that hour, though the
Zodiacal Light was dim, I could see that the houndaries of the stronger portion were, as on the preceding evenings;
the left-hand boundary being at AldeLaran, and the right, grazing the southern portion of the Pleiades. At 8h 30m
the Light could scarcely Le made out at all; and I could not, at any time, get the boundaries of the Diffuse Light.
From the llth till this evening, cloudy weather. To-night I was continually trouLled Ly living clouds, hut the
boundaries of the Diffuse Light were tolerably distinct. Alter 8 o'clock, nothing could Le had reliaLly.
OBSERVATIONS ON THE ZODIACAL LIGHT.
17
-
;
-
-
'
3
,-
'
-
•
•
18 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. '.I.
APRIL 20th, is:,:!: EVENING.
I. .-it. 23-' 55' N.: Lon. US' 38' K
Sun si-t Ci/i. 23m.
Stronger and 1'it't'usr Li^ht ;tt l/i. .'ill/,/
Cloudy weather since last date till this evening, when the sky was quite clear, allowing me to have a good obser-
vation. I could not observe, this evening, that the Stronger Light changed to the left, as previously noted; but if
this is the fact, the Milky Way would make it diiHciilt to l>c observed. At Sh 3flm, the Light was still visible, but
was too dim to give outlines.
OBSERVATIONS ON THE ZODIACAL I.1CILT.
ID
i=-3
S3
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R=a
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a
OBSERVATIONS ON TUB ZODIACAL LIGHT,
No. 10.
JUNE 7th, 1853 : EVKM.NG.
Lat. 20^ 10' N : Lou. 127 42' E.
Sun set B/i. 4GJ/«.
Stronger and Diffuse Light ut S/i. 2iiw.
Since April 29th, clouds or the moon interfered uniformly till last evening, which was on Sunday. This evening
had a very clear sky, and I observed carefully ; but I found it difficult to get boundaries, as they do not now have their
usual distinctness in the sky.
OBSERVATIONS ON THE ZODIACAL LIGHT.
21
22 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 11.
.11 NK t-lli. Isio : KVI.MV.
Lat. 2ti-' 10' N. : Lou. m - r>' E
Sun si't Kli. 47;«.
liiU'uw M.^'lil at 8/1. 'Mm.
Had a view of Zodiacal Li^ht, l>ut a brief (.me: lor clouds soon intervened, and so remained.
OBSERVATIONS ON THE ZODIACAL LIGHT.
23
~ e
E*
il
24 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 12.
JUNE llth. 1S53 : Moiixix.;.
L-,1 '2i: 10' X. : Lon. 127r 42' E.
Sun rose ;it ;j/;. ] 1m.
Stronger ami Diffuse Li.^lit, [ln\w not recorded, but pmbaMy at .'!;i. 30m.]
Clouds last evening. This morning I found the ililky \Vay interfering with the northern termination, but had
a fair observation.
OBSERVATIONS ON THE ZODIACAL LIGHT.
25
m
^-= =
26 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 13.
JUNE 15th, 1333 : Moiixixo.
Lat. 26° 10' N.: Lon. 127^ 42' E.
Sun rose 5/i. 12m.
Stronger and Diffuse Light [probably at 3 o'clock].
Kose fit 2h 30m. The view was not very satisfactory, owing to the strong inclination of the ecliptic to the horizon
Saw a. remarkable falling star. It moved with about half the swiftness usual with such boilies; hail a long tail,
say about 5° in length, and looked exactly like a comet. Its motion was in the line of a great circle. By and by,
the star or nucleus exploded and formed into three bright specks, strung lengthwise in a line with its motion and
tail. Then, after a little while all disappeared together.
OBSERVATIONS ON THE ZODIACAL LIG11T.
27
28 OBSERVATIONS ON THE ZODIACAL LIGHT.
'No. 14.
JUNE 23d, 1853 : EVENING,
Lat. 26^ 10' N.: Lon. 127° 42' E.
Sun pet at 6h. 501m.
Stronger Light at 8A. 30m, and 9/i. Diffuse at Sh. 30m,
Am carefully on the lookout for the Zodiacal Light, but clouds and the moon have interfered. This evening, got
a view, and found the light had apparently some new characteristics. The twilight is long, and it is not till 8h 30m
that I can mate out the outlines. The Stronger Light, at 81' 30m, seemed to stretch away to the northward, so as to
reach 70° along the horizon. Its right extremity, however, had the look of a hard sky, not the gauzy appearance
of the Zodiacal Light. It was very distinct. At I)1' the Stronger Light had ascended, extending, however, as- before,
70° along the horizon. The Diffuse Light is very faint, and can be recognized only by the dimming of the stars
behind it : it required a great many trials in order to get its boundaries.
OBSERVATIONS ON THE ZODIACAL LIGHT.
29
c ~ _'
.-.
30 OBSERVATIONS ON THE ZODIACAL LIGUT.
No. 15,
.11 XE 24th, ISJ.'J : KVJ.M.\<;,
Lat. 20° 10' N.: Lon. 127- I'J' K.
Sun sot fi/i. .">]«.
Stivn^or Light at 8A. 30m. Diffuse at SA. 30m.
n o
9 30
10 n
Had a good view of the Zodiacal Light, ami hnvc given its boundaries in the chart. At 10 o'clock, the Stronger
Light extended upward in an unusual manner; I have copied its boundaries as they appeared to me. The Diffuse
Light can no\v searo-ly lie made out.
It is possible that my watching the eastern and western portions nf the sky inure intently than the rest gives me
the impression that, there are more falling stars in those directions than in any other; hut so it seems to mo.
OBSERVATIONS ON THE ZODIACAL LIGHT.
31
32 OBSEEVATIONS ON THE ZODIACAL LIGHT.
No. 1C.
JUNE 2,'ith, 1853 : EVENING.
Lat. 26° 10' N.: Lon. 127° 42' E.
Sun set 6A. ">1«.
Stronger Light at 8A. 30m. and DA. l>il't'use [time not reeonlol.]
Had a very good observation. At 10 o'clock the Zodiacal Light was still very distinct.
OBSERVATIONS ON THE ZODIACAL LIGHT.
33
34 OBSERVATIONS ON THE ZODIACAL LKIIIT.
No. 17.
JUNE 57th, 1S53, (Monday) : EVENING.
Lat. 26^ 10' N.: Lon. 127 ' 42' K.
Sun set G/i. 51J«i.
Stronger and Diffuse Light at 8h. 30m. and 10A. 30m.
Sun's Longitude, 95° o'J'.
I suspected, from some glances at the Zodiacal Light, last evening, that I was giving it a too contracted boundary;
and, this evening, determined on a very careful observation, as the evening was very flue, atmosphere very clear, and
the sky unusually brilliant. After looking carefully myself, I called one of the oldest of the quartermasters, and,
drawing his attention to the light, I said: "You observe that, over there (pointing to the northward), the sky is
bluer and darker." He said "Yes." " You observe also, that up here (along the ecliptic), the stars are not so
bright as in the parts you have just been looking at." To this he also assented. " Now I want you to point out,
in the sky, the boundary between these two appearances; where the stars begin to lose their brightness, and the
sky begins to be less blue." He soon commenced drawing the boundaries, which corresponded exactly with those
which I myself had just mentally been giving it, and which are marked in the chart by the line of 8h 30maa«. At
10h 30m it had extended as shown in the chart atbbb. At 8h 30m the full extent of the Stronger Light along the
horizon was 75°. At 10h 30m the limits of the Stronger Light were not so well denned ; the light was stronger
between the horizon and 48 of Ursa Major, Coma Ber., and 5 Virginia, than it was above.
OBSERVATION'S OX THE ZODIACAL, LIGHT.
35
= 0?"
iV-T-^i^-l-rv-. ; ; :....- '
36 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 18.
JDNE 29th, 1853: EVEMM..
Lat. 2G^> 10' N.: Lon. 127° 42' E.
Sun brt \\li. iil.Jni.
Stronger Liglit at 8A. 15m. Diffuw n.t S/i. 30m.
8 30
9 0
9 30
10 (I Intense Light at 9/i.
11 0
Had a very good observation; sky very clear. Got two of the quartermasters, at 8h 30m, to draw the limits of
the Diffuse Light; they both agreed, and their ideas corresponded with ray own : these limits are given in the
chart; but the light defined was very dim, only a less depth "f color in the sky, and an inferior brightness of the
stars. At 9h there was, within the Stronger Liglit, a more effulgent portion, which is bounded by the zigzag line
a a a. At IP 30m, the ecliptic had sunk so near to the horizon that I could not get any boundaries, and the light
seemed to have nearly died away. At 10h 30m it was faint.
OBSERVATIONS ON THE ZODIACAL LIGHT.
37
- >==;
j a
38 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 19.
JUNE 30th, 1853 : EVENING.
Lat. 26^ 10' N.: Lon. 127° 42' E.
Sun set fi/i. film.
Stronger Light at Sh. 30m. and 9A. Diffusu at 8/t. 30m.
At 8h 30m the Stronger Light seemed to extend upward more than usual ; but I was suspicious of it, the evening
not being very favorable. At 9U it had its usual shape. The boundary of the Diffuse Light, as before.
OBSERVATIONS ON THE ZODIACAL LIGHT.
39
40 OBSERVATIONS ON THE ZODTACAL LIGHT.
No. 20.
JULY 1st, 1853 : EVBXIMI.
Lat. 26° 10' N.: Lon. 127^ 42' E.
Sun set at 6A. Slim.
Stronger Light at 8/1. 30m. Diffuse at S.'i. 30m.
90 90
9 30 9 30
10 30
Sun's Longitude, !)!) 2S'.
Had very good observations of the Zodiacal Light. Dr. - - and Mr. S— - were with me at half-past
8, and Loth agreed in the inferior darkness ("blueness" they called it) of the sky, and the inferior brilliancy of the
stars within the wide limits already noticed. I got them to give the boundaries, and we all agreed in them as
given in the chart in the outer, or dotted line, a. u.
At that time the gauzy light showed itself within the lint- of dashes, and the Stronger Light within the
full line, marked for that hour; and so with, the other hours. At 10h 30m there was no Stronger Light. At 11
o'clock there was only a dim marking of light about 4o Virginis, of which I could not get the boundaries. All
through the evening the light passed oil', at the right, into something which did not sceui to be the Zodiacal Light,
but stretched along the horizon in a space about G° wide, till it met the Milky Way.
[P. S., December 9, 1853. — The character of the Zodiacal Light for this season seems to have better developed
itself on this evening; and the charts from this on, for some time, have three kinds of boundaries: 1st. The dotted,
giving the boundaries of the sky where it is simply made pale, without any positive light; 2dly. The lines of
dashes, showing where the positive light ("Diffuse") commences; and lldly. The full lines, giving the boundary of
the "Stronger Light." Something of this kind seems to have shown itself on the evening of the 20th; but it, was
new, and we only get hints of it in the chart of that evening.]
OBSERVATIONS ON THE ZODIACAL LIGHT.
41
-
42 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 21.
JPLT 2d, 1853 : EVENZNO.
Lat. 26=> 10' N.: Lon.
Sun set 6/1. 5Hm.
Diffuse Light at 9A. 30m.
Clouds in the early part of the evening. At 9h 30m had an observation. Darkish clouds soon began to cross this
space, which, by contrast, gave me a better opportunity than before of judging about the newly observed appear-
ance within the outer or dotted lines, and tended to confirm the belief that it is real. Clouds prevented further
observations.
[P. S. 1856. — This reduced chart would not admit the whole of the dotted line as given in my original observa-
tions. This line reached 52° lat. at Ion. 1,60°, and thence continued at the same latitude to Ion. 115°, where it
terminated.]
OBSERVATIONS ON THE ZODIACAL LIGHT.
43
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mm
- -=
553
= =!
mm
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44 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 22.
JULY 4th, 1853 : EVENING (3d wag Sunday).
Lat, 29^ 9'N.: Lon. 131° 28' E.
Sun set 6/1. 5S»?,
Stronger Light at 8/;. Om. Diffuse at 8/1. Om.
8 30 8 30
9 30
Flying clouds this evening, but had good observations; results are given in the chart. The dimmed or paled
sky, as before; it is bounded by the dotted line. I cannot see that it changes its boundaries, as the others do,
while the night advances. At 9'' 30ra there was uo Stronger Light, and the Diffuse was very dim. Then came
clouds, and I could have no further observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
45
46 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 23.
JULY 5th, 1853 : Monuixo.
Lat, at 2/i. 30m., 29^ 3G' N. : Lon. 132' 5' E.
Sun rose 5/i. 9m.
Diffuse Light at 2/i. 30m. and 3A.
Had a fine observation this morning — the sky clear, and the Zodiacal Light very decided. There was no decided
"Stronger Light," though, toward the Pleiades, the Light gradually changed into a whiter appearance, of
which they were the centre. Probably the Milky Way prevented anything decided in this respect. I looked care-
fully for "a dimmer sky" and "dimmer stars" beyond these lines — such as we have in the evening; but could not
discern any.
OBSERVATIONS ON THE ZODIACAL LIGHT.
47
48 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 24.
JULY 5th, 1853 : EVENINO.
Lat, at S/i. 30m., 30° 47' N. i Lon. 133^ 3:>' E.
SSun srt 7/i.
Stronger Light at 8A. 30m. Diffuse at 8A. 30m.
90 90
9 30
I watched carefully, this evening, to see how the Zodiacal Light would first disclose itself to the sight. The eve-
ning good and clear. After the purple sunset-light was gone, a bright, steel, light succeeded along the horizon,
seemingly common twilight. This remained ; but at 8h its horizontal limits had contracted so, as to extend but 17°
S. and 55° N. of Venus,* then near setting. Its height was 20° ; towards its southern end this light began grad-
ually to slope upward; and also, on the sky above, an elongated, dim, milky light, gradually impressed itself.
At first it was doubtful; then less so; then, at 8h 15m, it was decidedly the Zodiacal Light reaching as high as 94
Leonis Majoris, and having the usual outlines of this Light. It was, however, dim above. At 8h 30m the whole was
clearly marked and distinct, and I was able to get outlines. At 9h 30m there was no Stronger Light ; at 9b this was
not strong, but stronger than the rest. At 10h 30m there was only a slight suffusion of light between the boundary
of 9h 30"' and the horizon. The dotted line a a shows the boundary of "the dimmed sky" as before.
At 8h 30m the bright sky on the right, into which the Zodiacal Light seems to run (if it is not a continuation of
it), extended 170° in width along the horizon till it reached 75° N. from Regulus: its upper edge thus extended
within 15° of the polar star itself.
Vrniis had then 25° of N. declination (gcomitrir).
OBSERVATIONS ON THE ZODIACAL LIGHT.
49
50 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 25.
JULY 6th, 1853 : MORNING.
Lat. at 2/i. 30m., 31' S' N : Lou. 1343 31' E.
Sun rose 5h. Cm.
Diffuse Light at Oh. 30m. and 2A. 30m.
Wont on deck at half an hour after midnight, and was surprised to find the Zodiacal Light, at this early time,
quite distinct. I asked the officer of the deck, Lieutenant M , if he could distinguish it ; and he had no difficulty in
doing so. I could see also that the whole of that portion of the heavens enclosed between the Milky Way and the
horizon, 75° wide (midway across which, slantingly, the Z xliacal Light passed), was not s.i black, and that the stars
were not so bright, as in the portion of the sky on the other side oi't'ie Milky Way, between Corona Borealis, and
the horizon N. of it, in which Lieutenant M also agreed with me. His answer was : ' ' Yes, now I can see it, since
you point it out." The portion of the dimmed sky of last evening's observations, still in sight, was also as dim as
in the evening.
There was a very splendid meteor this morning, just before I went on deck. It cast quite a strong light on the
deck.
OBSERVATIONS ON THE ZODIACAL LIGHT.
52 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 26.
JULY 6th, 1653 : ETEXINO.
Lat. at 8A. 30m., 32° 13' N.: Lon. 136<-' 34' E.
Sun set 7A. 5m.
Stronger and Diffuse Light at 8A. 30m. and 9h. 30m.
Zenith point, at 8k. 30m., Lat. 49° 0' N.: Lon. 217° 30'.
9 30 53 15 238 0
Clouds prevented any observations till 8h 30m. Afterwards, the view was interrupted by flying cirri ; but still I
was able to get reliable boundaries.
The outlines of the paled sky are marked as before, by a dotted line a a.
At 10 o'clock the Light was strongest about 94 Leonis Majoris, where it was equal to that of the Milky Way, in
the head of Scorpio, or about 10, 11, 14, and 15 Sagittas.
[P. S., 1856. — I am not able, in this reduced chart, to insert all of the dotted line. In my original chart, at Ion.
180° it reaches 49° 30' lat. ; it terminates at 125° of Ion., in lat. 52°.]
OBSERVATIONS ON THE ZODIACAL LIGHT.
53
;r=^
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54 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 2T.
JULY 7 tli, 1853 : MORNING.
Lat. at 3 o'clock, 32= 3C,' N.: Lon. 137^ 26' E.
Sun rose 5/t. 2m.
Stronger Light at 3k. Diffuse at mHniglit and 3/i.
My observations at half-past 12, yesterday morning, led me to attach more importance to appearances noticed
several evenings before at 10 and 11 o'clock — namely, something like the Zodiacal Light in the ro.sY, at tliosc early
hours. I had not recorded them, as I gave them little weight. Last evening, however, I turned In the east, at 9
o'clock, and took note of the appearances; though, from their v:cini;y to the horizon, I think nothing decided can lie
drawn from them. Still they are worthy of remark. The outline of this Light lor 91' 30™ is given in the chart. Its
upper part was lost in the Milky Way.
At II'1 30m p. m., I went on deck for another examination of the same; an:l continued observing till midnight, at
which time its outline was taken, as in the chart. This Light at 00, 01, 02, 9o, an 1 05 Aquirii, was as strong
as that about 11, 12, 13, 14, 15, and 10 Sigittre (just above Delp'iinus). Daring these observations, I was
inclined to confidence that this was the true Zodiacal Light; but, when I went on deck again, at '21' 30ra a. m., and
saw the undoubted Zodiacal Light stretching up in the sky, I thought I could see a diffeience; the hitter looking
soft and gauzy, unlike the hard look of the former. I have, however, given the boundaries of all from Oh 30"' to 3h
a. in.
The dim sky under the Milky Way was the same a ; yesterday morning-.
[P. S., 1856. — It will be seen from this journal, that this light in the east was seen subsequently on several nights
(July 9th, &c.) I finally came to the conclusion, from its pos'tion, that it was not the Zodiacal ! ight (in this
I Avas mistaken) ; and although, during the next year, I saw it repeatedly in the evening at the same hours — i. e.
about 9 or 10 o'clock — I made no record of it, which I now greatly regret. I was iiarful that I mjght embarrass
the true observations by others, of what was not truly Zodiaeal Light ; but w! o shall say what is and what is not
truly such? Therefore, nothing that seems to have a possible connexion with the subject is too small or too slight
to be noted.
It is possible that this nebulous matter, whatever it is, is sell-luminous, and thus gave me this light in the east;
but, more probably, it was still a reflection from the sun.]
OBSERVATIONS ON THE ZODIACAL LIGHT.
55
56 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 28.
JULY 7th. 1853 : EVENING.
Lat. at 8/1. 30m., 33^ 50' N.: Lou. 138° 53' E.
Sun set 7/i. 9^m.
tumper Light at SJi. 30m. Diffuse, 8/1. 30m. and ?/',
Sun's longitude, 105r-> 11'.
Zenith point, at 8A. 30m., Lat. 50- 3.V: Lon. 217".
90" 53 8 " 22.S
Clouds in the early part of tlie evening. Had good observations at 8h 30m and at 9 o'clock, tor which see chart.
At 9h there was no Stronger Light. After this, the sky, for some distance up from the horizon. Became hazy. Tin1
paled portion of the sky now extends up quite to the Milky Way,
OBSERVATIONS ON THE ZODIACAL LIGHT.
67
-
FL:
6^
if
58 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 29.
JULY Sth, 1853 : EvExrxo.
Lat. 350 12' N.: Lon. 139° 44' E.
Sun set 7/i. 13m.
Stronger Light at 97i. Diffuse, 9/i. Om. and 9A 30m.
Zenith point, at 9/i., Lat. 54^ 25'N.: Lon. 228
Observation, this morning, prevented by clouds. The moon this evening interfered with the Zodiacal Light till
9 o'clock; then got observations. At 9h 30m the Light was very dim — scarcely perceptible. Even the Stronger Light
at 9b was feeble compared with its recent appearance.
OBSERVATIONS ON THE ZODIACAL LIGHT.
59
60 OBSERVATIONS ON THE ZODIACAI, LIOHT.
No. 30.
JCTLT 9th, 1S53 : MORNING.
Lilt. 35° 12' N.: Lon. 139° 41' E.
Sun rose 4A. 58»».
Stronger and Diffuse Light at 3A. Om. and 3h. 30m.
Was up at 2h 30m; the sky not at its brightest, but still pretty good. Found it difficult to get exactly the limits
of the Diffuse Light at their upper extremity, owing to its dimness. At 3h 3CT the Stronger Light was very bright,
and showed itself decidedly, even in the Milky Way. Indeed, I should have supposed it to be dawn, but for its con-
fined limits. These, now, gradually spread, and soon ended in the dawn.
OBSERVATIONS ON THE Z'linACAL LIGHT.
61
62 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 31.
JULY 9th, 1S53 : EVENING!.
Lat. 35° 12' N.t Lon. 139° 44' E.
Sun set 7A. 12m.
Stronger and Diffuse Light at 9A. 15m. and 9&. 30m.
Zenith point, at 9A., Lat. 54° 40' N. : Lon. 229°.
Moon interfered with the Zodiacal Light till 9b 15m, when it set. The atmosphere was remarkably clear, and the
Light better than several evenings previous at these hours. At 10'', atmosphere still clear, but the Zodiacal Light
proper was gone, except a brightish spot from 94 to 70 and 68 Leonis Majoris; but, although the elongated Zodiacal
Light had no longer its proper limits, it seemed now to have ascended, and widened over what I have usually called
the dimmed or paled sky; all of which was now filled with a whitish light, so as to be very striking.
OBSERVATIONS ON THE ZODIACAL LIGHT.
63
64 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 32.
JULY 9th, 1853 : EVENING.
Lat. 35° 12' N.: Lon. 139° 44' E.
Sun set 7A. 12m.
Zodiacal Light in the East at 9A. 30m. and 10 o'clock.
At 9h 30m, I turned to the eastern sky, and thought that I could make out a strip of brightness with boundaries as
in the chart. At 10h, this brightness was more striking; and I could have no suspicion, in this case, as on a former
occasion (see No. 27), that it was an accidental brightness of the horizon: for there was now a dark haze between
its lower part and the horizon. Still I had some doubts of its being the true Zodiacal Light. At 1011 45m it was so
strong as very much to dissipate doubt. I could scarcely resist the full conviction that it was the real Zodiacal
Light.
[P. S., 1856. — See No 42, for another observation of this kind, and for remarks.]
OBSERVATIONS ON THE ZODIACAL LIGHT.
65
Z\O l\5_ i\0 iJ Itf I J j\
-r-i-r-^l . I . ,1 . i . i I i i . ,-T.i I . i I 1 .1 L i H
6f> OBSERVATIONS ON THE ZODFACAL LIGHT.
No. 33.
JULY lltli, 1S.53 : Monxixa.
L.it. 35r' 12' N.: Lon. 139° U' E.
Sun rose 4A. 50m.
Stronger and Diffuse Light at 2k. 30m.
Kose at 2'1 30m and took nhsri-vaticins. It is difficult now to get boundaries to the Stronger Light, it changes so
gradually and evenly into the Diffuse.
OBSERVATIONS ON THE ZODIACAL LIGHT.
68 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. iJ4.
JULY llth, 1853 : EVENING.
Lat, 35° 12' N. : Lon. 139° 44' E.
Sun set Ih. llm.
Diffuse Light at 10A. 30m.
Zenith point, at lO/i. 30m., Lat. 58° 30' N.: Lon. 263°.
Moon in the early part of the evening. At 101' 30™ went on deck. Sky very clear. Some remains of the Zodiacal
Light still very distinct. The sky above, heretofore called "the dim or paled sky," is beginning to show decided
and positive Zodiacal Light. It was quite bright with it this evening, the boundaries running from C4 Ursa)
Majoris, &c., as in the chart, marked a a a.
OBSERVATIONS ON THE ZODIACAL LIGHT.
69
=
i£ i
70 OBSERVATIONS ON THE ZODIACAL LIGHT,
Bfo. 35.
Jt'LY 13th, 1853 :
Lat. 35° 12' N.: Lon. 139° 44' E.
Stm rose 5A.
Stronger and Diffuse Light at 2/i. 30m. and 3 o'clock.
Clouds yesterday morning. At 10h 30m last evening I examined the eastern sky, and saw the whitish appear-*
ance recorded in No. 32 of this book ; it had the same boundaries as given there for 10 o'clock, and was as bright as
then.
Went out again at midnight, and saw a similar brightness, but thought it too uncertain to be relied on.
Was out again at 2h 30m ; and now there could be no mistake. At 31' 30m also tried to get an observation ; but at
this hum- the dawn is beginning to show itself. At 2h 30m the brightness between 86 and 92 Ceti and a. Avietis,
marked aua a in the chart, was equal to that of the Milky Way at 11. 12, and 14
OBSERVATIONS ON THE ZODIACAL LIGHT.
72 OBSERVATIONS ON THE ZODIACAL LIGHT.
JULY Uth, 1.8o3 : Mouxixr..
Lat. 35° 23' N.: Lon. 139= 41' E.
Sun rose 5h. OJw.
Diffuse Light at 2A. 45m.
Atmosphere hazy. Got outlines at 2h 45m. No Stronger Light, in consequence of haziness along the horizon.
OBSERVATIONS ON TUB ZODIACAL LIGHT.
73
74 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 37.
JULY 15th, 1853 : MORNING.
Ldt 350 23' N.: Lon. 139° 41' E.
Sun rose 5/t. 1m.
Strniigrr and Diffuse Light l/i. Om.
1 30
Z 0
3 0
Was on dock at 1 o'clock this morning, and found the Zodiacal Light, at that hour, perfectly distinct. For bounda-
ries, at different hours, see the chart. Dawn comes soon after 3h.
OBSERVATIONS ON THE ZODIACAL LIGHT.
75
in
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 38.
JULY 16th, 1853 : MOBNDHJ.
Lat. 35° 23' N. : Lon. 139° 41' E.
Sim rose 5h. 1m.
Stronger and Diffuse Light at 2 and 3 o'clock.
No evening observations, on account of the moon. Was called this morning when the moon had set, and took
boundaries; for which see chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
77
r-;:i---rs«-*sis..--— ' -—=—-«===-= • -*^=s=^ ---, -
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78 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 39.
JULY 18th, 1853 : MORNING.
Lat. at 3h., 33° 42' N.: Lon. ISS^ 13' E.
Sun rose 5h. 7m.
Stronger and Diffuse Light at 2 and 3 o'clock.
The moon set towards 2 o'clock.
There was a heavy rain in the early part of the night; and on going on deck, just before 2" this morning, I found
the atmosphere remarkably clear, and the sky unusually fine for observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
79
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 40.
JULY 19th, 1853 :
Lat. at :{/i., 32? 4' N.: Lou. 135° 53' E.
Sun ruse 5A. ]0<».
r Li.nht at :\!i. : Uilluse Li^'lit. 3/i. 30m.
Moon did not set till just after 3 o'clock. Was able, however, at 3", to get the boundaries of the Stronger Light;
at 81' 30m, got those of the Diffuse, as in the chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
81
82 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 41.
AUGUST 4th, 1853:
Latitude at SA., 21? 45' N.: Longitude 121s 33' E.
Sun set 6h. 34m.
Stronger Light at 8A. : Diffuse Light at 8 and 9 o'clock.
Clouds since July 19th. This evening got observations. At 9h, there was no Stronger Light, and all was very dim.
At 8h, the Light just below 43 and 39 Virginis (marked a a a in the chart), was equal to that of the Milky Way
about 23 and 26 Scorpionis (marked in the chart by b b b~).
OBSERVATIONS ON THE ZODIACAL LIGHT.
83
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11
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 42.
AUGUST 5th, 1853 : MOBNLNG ; also Eastern Light the evening previous. -
Lat, at 4 a. m., 21° 31' N. : Lon. 121° 3' E.
Sun rose? 5A. 3!l/».
Stronger Li.^lit at Hi. : Diffuse. S/i. 30m. and 11A. p. m., of 4th, and 2A. and 5/i. of 5th.
At 8" 30m, last evening, I turned to the eastward, and found there an appearance much like the upper extremity
of the usual Zodiacal Light. Its boundaries are given in this morning's chart. Distrustful of my judgment, I got
one of the quartermasters to look, who readily made it out and deliued its boundaries — -the same as they appeared
to me. Its brightness was equal to that of the Milky Way about 1(J Aquihe (marked a a a at the upper end of
the chart). It could not be confounded with the Milky Way, 'between which and it there was a decidedly dark
space ; as there was, also, on the other side of the Milky Way, between the latter and the top of the Western Zodiacal
Light, then in sight.
At II1' went on deck, and found the same appearance, only it had changed its place, and was larger, as in the
chart: the brightness was about equal to that of half-past eight.
At 2", on deck again; and now the Zodiacal Light was very decided. There could be no mistake about it. At 4",
another observation, and now had the Stronger Light. I cannot assert that the Eastern Light, at 8" SO"1 and II'1 p.
m., was the real Zodiacal Light; but it was much like it.
[ Brooklyn, 1856. — The above remarks, with others of previous date, on this Eastern Light, will show my exceeding-
caution about admitting any tiling new, and my fears about embarrassing the true observations with any thing uncer-
tain. A letter from me, published in May, ultimo, in the American Astronomical Journal, has led Baron Humboldt
to quote from his unpublished MSS., in which are records of a similar light seen by him in the cast, in the evenings
of the 17th and 18th of March, 1803, in hit. about 1:5° N. ; which, however, lie supposes to be only a reflection from
the Western Zodiacal Light, then shining with exceeding brilliancy. (See Astronomisclie Nachrichten, No. 980.) In
No. 998 of the Astro. Nachrichli'ii, is another paper on this subject by Mons. Theo. J. C. A. Brorsen, of Serptenberg,
in Germany, who calls this Eastern evening light by the appropriate name of gegenschein (a shining opposite), and
informs us that he had seen it regularly at that place during the two previous years. His paper concludes as follows:
"The ycijeitscJtcii) is visible, not only at the vernal, but also at the autumnal equinox; at the former time more dis-
tinctly. A faint trace of it becomes visible in January, from which time it grows stronger till March, when, and in
April and the early part of May, it is quite distinct and broad. A much smaller and weaker gegenschein appears in
Sept ember, October, and November. I have become convinced, by frequently repeated observations, that, in both
cases, the brightest part of the gegenscltcin is directly opposite the place of the sun; so that a calculation of the great-
est light frequently coincides to a degree with the point of opposition to the sun. The observations proved that the
vernal </a/enschein, about the middle of April, joins the Westerly Zodiacal Light by a strip or belt of light, which is, at
first, very weak, but becomes by degrees more luminous ; the autumnal gegenschein appears, in the first part of No-
vember, to be elongated along the ecliptic by a weak zone of light as far as the western horizon, which zone of light
is, by degrees, transformed, by increasing luminosity and more distinct basis, into the well-known phenomenon of the
Western Zodiacal Light. From this time to the commencement of March, its apex remains almost stationary in the
region of r 1 and r 2 Arietis. Both gegenschein could be seen here, at the same season, on every clear evening; and
even distinctly in the light of the new moon."]
OBSERVATIONS ON THE ZODIACAL LIGHT.
-
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86 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 43.
AUGUST 16th, 1853 : MonNixfl.
Lat. 23° 2' N. : L..n. ll.T' 28' E.
Sun rose at 5A. 40///.
Stronger and Diffuse Light at 4 o'clock.
Since last date (5th instant), have had unbroken cloudy weather (except one night, which was hazy), until last eve-
ing. Then the moon interfered. Eose at 4'1 this morning, and took boundaries as in the chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
87
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L==3
fll
OBSERVATIONS ON THE ZODIACAL, LIGHT.
No. 44.
AUGUST 17th, 1853: MORNING.
Lat. 23° 2' N. : Lon. 113° 28' E.
Sun rose 5/i. 42m.
Diffuse Light at -1 o'clock.
The Stronger Light appeared to have the same boundaries as yesterday morning; hut, heforc I could take them,
clouds filled up that part of the sky; nor could I afterwards have any observation.
OBSERVATIONS ON THE ZODIACAL LIGHT.
89
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ei
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ife
90 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 45.
AUGUST 2Cth, 1853 : EVENING.
Lut. 23^ 2' N.: Lou. 113° 28' E.
Sun set 6/i. l!)m.
Diffuse Light at 8/1. 30m.
Clouds since last date (17th). Prevented this evening-, hy the same cause, from observations till 8h 30'", when (h
sky cleared, and I had the Zodiacal Light as in the chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
01
12
Q2 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 46.
AUGUST 29th, 1853 : EVENING.
Lat. 23° 2' N. : Lon. 113= 28' E.
Sun sot 6/1. 16;n.
Stronger and Diffuse Light at 1h. 30m.
Both the Stronger and Diffuse Lights are now much fainter than they formerly were.
OBSERVATIONS ON THE ZODIACAL LIGHT.
93
-~r_i: -^
•
94 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 4?.
AUGUST 31st, 1S5S: EVENING,
Lat. 23° 2'N.: Lon. 113^ 28' E.
Sun set 6/>. 15}m.
Stronger and Diffuse Light at "ih. 30m.
Nothing remarkable this evening; for tht observation, sec the chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
95
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 48.
SEPTEMBER 1st, 1853 : EVENING.
Lat. 23° 2'N.: Lon. 113° 23' E.
Sun set G/i. ] 1m.
I 7/i. 20m. f
Stronger Light J 7 45 J Diffuse, 7//. 20m.
8 0 ( 80
Took boundaries as iu the chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
97
gg OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 49.
SEPTEMBER 2d, 1853 : MORNING.
Lat. 23^ 2' N. : Lon. 113° 28' E.
Sun rose 5/i. 45m.
Stronger and Diffuse Light at 2h. 40m. and 3A. 30m.
EU'ulgent Light at 3A. 51;»
The moon now, once more, admits of morning observations of the Zodiacal Light. At 2'' 40m this morning, it
was already very distinct.
At 3h 54m, the Stronger Light became, almost suddenly, much stronger than before ; the limits of this new effulgence
being at the zigzag line a a. I supposed, at the time, that this was owing to the moon, then near its rising; but
when the moon showed itself, at 4" 18"', I saw that its light was too faint to produce such a result. At 4" 30™, the
light spread laterally, and dawn had come.
[1856. — I afterwards became familiar with this effulgent light, as the book will show, passim.]
OBSERVATIONS ON THE ZODIACAL LIGHT.
99
- :; .2
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100 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 50.
SEPTEMBER 3J, 1853 : MOKNINO.
Lat. 23= 2' X. : Lon. 113= 28' E.
Sun rose 5A. 46m
Stronger and Diffuse Light at 3h. Om.
3 30
4 0
4 24
Cloudy last evening. Had fine observations this morning; sky perfectly clear quite to the horizon. The Light
was strongest at 31' 30"' ; dawn at 4" 30"'.
OBSERVATIONS ON THE ZODIACAL LIGHT.
101
.
-
102 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 51.
SEPTEMBER 3d, 1S53 : ETKMXO.
Lat, 23° 2'N.: Lon. 113° 28' E.
Sun sel Cli. 12m.
Stronger and Diffuse Light lit "ih. 30m.
Hail good observations of the Zodiacal Light. At 8h 30" it Avas still visihlc, hut loo i:iint to give ,1 reliahle outline.
OBSERVATIONS ON TI1K ZODIACAL LIGHT.
103
&3 a
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523
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104
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 52,
BE] PEMBEG 5th, 1853 MOB .
Lat. 23 2' N. : Lon IP; 28 r,
Sun rose 5/i. 47,v.
Sti-.in erLighl i 30i i. Diffuse l/i 30 » an i 3 r
Piosc early for observations. At T' 30'" the Lii^tt was vow ii ici ! •.! : 1> it'll i'
31', cilouils prevented my getting ]»<\\u .liirii's of ' he ^i onj er Liglit.
:in .1 tl:c S rcj icr l:in !^. At
OBSERVATIONS ON THE ZODIACAL LIGHT.
105
^- . . .. -
!;-;: - : ;
JOG OBSERVATIONS ON THE ZODIACAL LIGHT.
SEPTEMBER 12th. 1S33 : Jlor.xixo.
Lat. 23: 2' X. : L™. 11.3-' 28' E.
iMiu rn.si- j.'/. J'.iui.
Stronger Liu'ht 4A. Om. ar.il •!.'.. 2h». DilYu.sr Li-ht 4/i.
Clouds since the 5th; moon also in the evening. This morning ha 1 goo 1 <>l>srrvatk>ns at 4\ ami 4" 24'". At I'1
24"' dawn had already commenced, and was too strong to allow me to get the limits of the Diffuse Light.
OHSKIIVATIONS OX THE ZODIACAL UGHT.
107
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1()S OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 54.
SEPTEMBER 13th, 1853 : MOBNIXQ.
Lat. 23° 2' N.: Lon. 113^ 28' E.
Sun rose 5/i. 49m.
Diffuse Light at 2 o'clock.
Got an observation at 2 o'clock, only for the Diffuse Light. I had to struggle, for this, with the clouds, which
soon after put a stop to all further observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
109
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e-t^
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HO OBSERVATIONS ON THE ZODIACAL LIGHT.
SEPTEMBER llth, 1853 : MORNING.
Lat. 23? 2' N.: Lon. 113^ 28' E.
Sun rose 5h 49 Jm.
Stronger Light 2h. 30m. Diffuse 2h. 30m.
30 30
40 40
4 2S
Moon set about 2h 30™. From that time on, had excellent observations, the atmosphere being remarkably clear.
At 4h 28™ dawn had advanced so as to overpower the Diffuse Light. The Stronger Light was remarkably bright
just before dawn.
OBSERVATIONS ON THE ZODIACAL LIGHT.
Ill
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 56.
SEPTEMBER 15th, 1853 : MORNING.
Lit. 23 3 2' N. : Lon. 113^ 28' E.
Sun rose 5A. 50m.
Stronger Light 3/i. 15in. Diffuse Light 3A. 15m.
40 40
4 20
4 26
Moon set at 3" 15m. Had a good observation immediately afterwards, and also at 4". At 4h 20m, the Diffuse Light
was too faintly marked to give a reliable outline. The Stronger Light now becomes more and more intense till just
before dawn; then it begins to spread laterally; finally, it gradually melts into the dawn. I noticed this morning,
that this lateral spreading is more rapid and greater towards the N. than towards the S. ; its boundaries at 4" 26m arc
marked by the dotted line: at 4h 30m it was merged into dawn.
OBSERVATIONS ON THE ZODIACAL LIGHT.
113
?=3
MS
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114 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 57.
SEPTEMBER 24th, 1853 : EVENING.
Lat. 23° 2' N. : Lon. 1133 28' E.
Sun set 5/i. 50m.
Stronger and Diffuse Liyht at 7 o'clock.
Moon in the morning : clouds uniformly in the evening since last date. This evening, had a clear atmosphere and
a very good time ior observation. The evening Zodiacal Light now, though not show}', is extremely interesting; as
it presents itself broadside to us, and offers a good opportunity of ascertaining its northern limits. These appear to
be about 45° from the ecliptic. The Stronger Light is not striking, owing to its proximity to the horizon.
OBSERVATIONS ON THE ZODIACAL MGHT.
115
HE-'
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 58.
SEPTEMBER 27th, 1853 : EVENING.
Lat. 23'= 2'N. : Lon. 113° 28' E.
Sun set 5/i. 48m.
Str. nger Light 7A. Diffuse Light 7/i. Om.
7 30
8 0
Had good observations this evening, the sky being very clear; and, as they are important at the present time, as
showing the northern limits of the Zodiacal Light, I observed with particular care. The Light is not strong, and the
outlines are not very decided; but I believe I have, in consequence of great care, been able to get them correctly. At
8", the full boundaries of the Diffuse Light could not be had reliably. The Stronger Light, at 7", was not very de-
cided; and this Light, in consequence of its proximity to the horizon, or from some other cause, is not as strong as
formerly.
OBSERVATIONS ON THE ZODIACAL LIGHT.
117
fr
-
33
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118 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 59.
SEPTEMBER 28th, 1853 : EVENING,
Lat. 23° 2'N.: Lon. 113° 28' E.
Sun set at 5h. 47Jm.
Stronger Light at 7/i. Om. Diffuse at Ih. Om.
1 30
8 0
8 30
Had observations, for which see chart. At 8h 30'", the upper end of the Diffuse Light was still well defined; hut,
fit its lower, or right-hand extremity, I could not get reliable boundaries.
OBSERVATIONS ON THE ZODIACAL LIGHT.
119
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m
}2() OBSERVATIONS ON THE ZODIACAL LIGHT.
No. CO.
SEPTEMBER 30th, 1853: MORNMO.
Lat. 22° 23' N.: Lon. 113° 32' E.
Sun rose 5A. 55m.
Stronger Light at 3h. Om. Diffuse at 2/i. Om.
2 30
3 0
The sky, this morning, was remarkably clear — so clear, that I could easily see stars of the 6th magnitude with the
naked eye. Rose at 1" 30™, and was on deck till the moon showed itself, near halt-past 3. Observed very carefully,
in order to see at what time the Zodiacal Light would first show itself. It was at two o'clock that I could first make
it out: it was dim. At 2" 15m, it was decidedly exhibited; at 2" 30m, the Stronger Light developed itself, and at 3",
it was strong enough to give me its outlines reliably. As the moon was now approaching the horizon, I watched to
see whether it would increase the brightness of the Zodiacal Light, and was pretty well satisfied that it did. The
Zodiacal Light changed gradually from its former soft color into a hard white, and grew brighter and brighter — the
limits df the new brightness keeping between 11 and 16 Hydra1, and 48 Cancri — till just before the moon rose, when
they suddenly expanded along the horizon. The unilluminated part of the moon (which was uppermost) was so
bright as to show itself most distinctly. Query: whence came the light illuminating that portion of the moon so
greatly ?
[P. S., 1856.— Was it from the Zodiacal Light ?]
OBSERVATIONS ON THE ZODIACAL LIGHT.
121
122 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 61.
SEPTEMBER 30th, 1853 : EVENING.
Lat. 22° 23' K.: Lon. 113° 32' E.
Sun set 5A. 45m.
Stronger Light at 7A. 0;n. Diffuse Light at 7/i. Om.
7 30
S 0
Had a very good evening for observations. The Stronger Light is now greatly dimmed by haziness at the horizon.
Noticed carefully to see at what time the Light could no longer be seen. At 8b30m, it was still distinct; but I could
not get its limits reliably. At 9", I rather thought I could mate it out ; but there was no longer any certainty
about it.
OBSERVATIONS ON THE ZODIACAL LIGHT.
123
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124 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. G2.
OCTOBER 1st, 1S53 : MOENINO.
Lat. 22° 23' N.: Lon. 113D 32' E.
Sun rose 5A. 55w.
Stronger aud Diffuse Light at 3/i. Om.
3 30
4 0
Eose before 3", and had good observations till the moon came. At 3", the head of the Diffuse Light was lost in the
Milky Way, and I could not make it out. Watched again to see what effect the approach of the moon would have.
At 3" 30'", the central (Stronger) Light was bright. It then soon began to increase in strength, and to change its
color from a soft white with a little tinge of yellow, into a hard steel Avhite; the whiteness went on increasing, and
the Light grew in intensity; also widening, but still keeping within the bounds of the Diffuse Light, till, suddenly,
it spread generally over the face of the eastern sky, and the Zodiacal Light was over. The moon soon after appeared
above the horizon.
OBSERVATIONS ON THE ZODIACAL I/1GIIT.
125
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126 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 63.
OCTOBER 1st, 1853 : EVEXISO.
Lai. 22° 23' N.: Lou. 113° 32' E.
Sun set at 5A. 44-m.
Stronger Lijht at 7A. Om. Diffuse at ~lh. Om.
7 30
8 0
8 45
Had a fine evening for observing the Zodiacal Light. At 9h, it was very faint, but seerned to have the same limits
as at 8h 45™. At 9h 15™, nothing could be made out. Last evening I drew lines as in the chart at 8h 45m; but, con-
cluding that they could not be fully trusted, I did not copy them into my MS. This evening, without being on the
lookout for such appearances, I was struck with the same thing, at that time — namely, a great change in the direc-
tion of the Zodiacal Light, and I have recorded it in the chart (see 8h 45m). This is doubtless owing to the great
change in the angle which the ecliptic makes with the horizon, as the night advances.
OBSERVATIONS ON THE ZODIACAL LIGHT.
127
128 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 64.
OCTOBER 3d, 1S53 : MOBXIXG.
Lat. 22° 23' N.: Lon. 113° 32' E.
Sun rose .">// .Vi.Jm.
Stronger Light at 3h. Om. Diffuse at 2A. Om.
40 30
4 30 40
Went on deck at 2 a. m.; and found the Zodiacal Light, though not bright, still quite decided. Lieutenant M — —
then the watch officer, was also able to make- it out. In the neighborhood of Pnvsepe, its brightness was then equal
to that of the Milky Way between Sirius and 26 of Monoceros. At 3 o'clock, the Diffuse Light at 1C Cancri was
equal to the same. At 4", the Stronger Light was very brilliant, its outline as in the chart; but immediately after
this, it began to sink rapidly, and at 4h 30m, it had got d.iwn to the limits given also in the chart. I was not looking
for this sudden change, but it was in accordance with observations on previous occasions. This Light, alter it had
sunk down, was also much dimmer than at 41' ; at 4" 371", there was a sudden and rapid spread of light beyond the
Zodiacal Light bounds, and dawn had come.
OBSERVATIONS ON TUK ZODIACAL LIGHT.
129
130 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 05.
OCTOBER 3d, 1S53 : EVENINO.
Lat. 22° 23' N.: Lon. 113= 32' E.
Sun set 5A. 421m.
Stronger Light at Gk. 4om. Diffuse at 7/i. 5m.
C 57 7 30
75 SO
8 30
9 0
Had a, fine sky for Zodiacal Light, and watched it attentively. Twilight left behind it a dull, rosy light, which
gradually grew dimmer, and then died away. At Gh 42"', there was almost a sudden flush of soft white, which was
the Zodiacal Light ; at 61' 45'°, it was as in the chart, the whole of it being the Stronger Light, with a little of the
Diffuse Light travelling ahead at its front or upper end, the latter at 6" 50'" being at 38 Librte. The Light was strongest
between 99 and 109 Virginis. Now commenced a singular sight. This sudden flush at 6" 54m, or thereabout (for I
could not. tell exactly), began rapidly to grow dim, and to contract its limits; and at 6" 57"1, it had receded to the
boundaries given for that time in the chart, and had only half of its former intensity. Then, in a few minutes, it
began to widen again (though with only the lesser intensity of G'1 57'"), and also to have a Diffuse Light along its
borders. At 7'1 5'" the Stronger Light had reached its former bounds as at Gh 45'"; the Diffuse being as given in the
chart.
I noticed the same thing also on Saturday evening, but did not record it. It was so singular, that I thought it
might be an ocular deception ; bat it showed itself decidedly on Sunday evening, just as described to-night.
At 9h, the Light, was very faint. I knew it had extended itself as in the chart, because, in the early part of the
evening, the space about 27, 4-1, and 30 Ophiuchi was quite dark, and now it was brightened up continuously with the
space to 1 and 2 Ophiuchi.
. T.si-.RVATIONS ON THE ZODIACAL LIGHT.
131
132 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. CG.
OCTOBER 4th, 1853 : MOKNINO.
Lat. 22° 23' N.: Lon. 113° 32' E.
Sun rose 5A. 5Gm.
Stronger Light at 3A. Om. Diffuse at 3h. and 4/i.
4 0
4 30
A good morning for observations. At 4h 26"1, the Stronger Light sunk down, and diminished in intensity. At 4'1
3CP, it was as in the chart. Then it grew once more in strength. At 4h ST"1 dawn arrived.
OBSERVATIONS ON THE ZODIACAL LIGHT.
133
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134 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 67,
OCTOBER 8th, 1853 :
Lat. 22° 11' N. : Lon. 113° 36' E.
Sun rose 5A. 57.};n.
Stronger Light at 3A. Om. Diffuse 3/i. 0»i.
40 40
4 30 &c. 4 30
Clouds since the morning of the 4th. This morning the sky was remarkably clear, and I hail good observations.
The Milky Way prevented my ascertaining exactly the upper limits of the Diffuse Light at 3 o'clock. Was struck,
this morning, with the difference between the Zodiacal Light and that of the Milky Way. The former is a soft,
warm light, a little tinged with yellow, as if the sun were just going to rise; this was the appearance of the Stronger
Light at 3 o'clock. This brighter part was unusually brilliant this morning. I could see nothing in the Milky
Way to compare with it in brilliancy. This was particularly the case from 4h to 41' 30m ; the zigzag line bounds a
portion more effulgent than the rest. The suddenness of the change from the Zodiacal, to dawn light, is worthy of
remark. This morning, I turned my eyes from the Zodiacal Light, in order to make some annotations, and when,
after writing but twelve words, I looked again, the light had spread, and dawn had come. This was at 4" 34'".
OBSERVATIONS ON THE ZODIACAL LIGHT.
135
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136 OBSERVATIONS ON THE "ZODIACAL LIGHT.
No. 68.-
OCTOBER 18th, 1S53 : EVENING.
Lat. 22? 11' X. : Lon. 113° 36' E.
Sun set 5A. 2:iw.
Diffuse Light at C/i. 40m.
Clouds iiniformly since my last entry (Sth instant), except the evening of the 15th, when the moon interfered.
This evening had a clear western sky. Watched to see if I could discern when the twilight changed into the Zodiacal
Light. Could not tell. The position of the ecliptic is, however, unfavorable for this. The western sky, alter sun-
set, continued red for a considerable time ; this redness at last contracted its dimensions, first vertically, then hori-
zontally ; gradually the red grew dim, and changed by imperceptible degrees to a white light, the white expanding.
At G1' 30'", I "knew I was looking at the Zodiacal Light; but it was impossible to say exactly when it had become so.
The moon, after 6" 40ra, prevented further observations.
OBSERVATIONS ON THE ZODIACAL LICI1T.
137
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138 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 69.
OCTOBER I9th, 1853 : EVENING.
Ut, 22':' 11' N. : Lon. ll.'i-' 36' E.
Sun set 5A. 28Jm.
Diffuse Light at 7/i.
Evening pretty favorable for Zodiacal Light. S»me cirri prevented my getting the Stronger part. Was gratified
in being able to get the Diffuse lieyoml the Milky Way. These evening observations are still particularly interest-
ing, as tlio sun still strikes laterally; and consequently they help us to ascertain the breadth of the Zodiacal Light
northwardly. Watched to see when I could first make it out to be the Zodiacal Light: it was so first, decidedly, at
6" 3flm. Moon rose at I7" 15™. In the chart the boundary is double, at its lower end, on the left. My eye sometimes
fixed on one, sometimes on the other, as the true boundary. I could not decide which of the two lim.-s to adopt.
OBSERVATIONS ON THE Z( HHAI'AL LIGHT.
139
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HO OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 70.
OCTOBER 20th, 1S53 : EVENING.
Lat. 22- 11' N.: Lon. 113^ 30' E.
Sim set 5A. 28m.
Stronger Light at fih. 30m. Diffuse CA. 4.">«i.
70 70
Fine evening for observations. Watched carefully to trace the first indications of the Zodiacal Light. The twi-
light contracted and faded; and then (I could not tell exactly the time), there was a changing into the Zodiacal
Light. I knew it to he the latter, tor the first time, at 61' 30m ; hut as yet this was only the Stronger Light, the
bounds as given in the chart. Then this Stronger Light began to widen, and the Diffuse Light to edge it, and to
ascend pretty rapidly; and, at 6h 45", they were as in the chart.
OBSERVATIONS ON' THE ZolUACAL LIGHT.
141
142 OBSERVATIONS ON THE ZODIACAL LIGHT
No. 71.
OCTOBER 21st, 1853 : EVENE?S.
Lat. 22:J 11' N.: Lon. 113° 36' E.
Sun sot 5^. 27 m.
Stronger Light at 6A. 30m. Diffuse at eh. 45m.
6 45 70
7 30
Fine clear evening. At Ch 30™, got the Stronger Light : but the limits of the Diffuse were not reliable. At 6* 45m,
got both. At *7h, Stronger Light with outlines as at fi'1 45'", but much dimmed. At 71' 30m, this light scarcely, if at
all, distinguishable from the Diffuse; the latter, itself, faint. At 8h, its lower boundaries — •/. e. from Corona Borea-
lis to a Ophiuchi, alone reliable, but very faint.
OBSERVATIONS ON THE ZODIACAL LIGHT.
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144 OBSERVATIONS ON TIIE ZODIACAL LIGHT.
No. 72.
OCTOBER 22d, 1853 : EVENINS.
Lai. 22° 23' N.: Lon. 113» 32' E.
Sun set 5A. 26m.
Stronger Light at 6A. 30m, Diffuse at G/i. 30m.
6 45 a 45
70 70
i 30
Atmosphere remarkably clear. Got the Diffuse Light at 6" 30™. About 6h 52m, the Stronger Light began to fade,
and also to spread upward a little. At 7" 7m, could not distinguish it from the Diffuse Light. At 71' 30™, no Stronger
Light; but the Diffuse Light very bright and distinct. Seemed to be more so than an hour before (the ecliptic
now making a larger angle with the horizon) ; its limits appeared to be the same as at 7h. At 8h, it was still very
bright. At 8h 30m, quite distinct. I now turned towards the east, to look for the moon's illumination.
ORSKRVATIONS ON THE ZODIACAL LIGHT.
145
IK', OBSERVATIONS ON THE ZODIACAL LIGIIT.
No. 73.
OCTOBER 27th, 18J3 : EVEXLVS.
Lat. 22° 23' N.: Lon. 113° 32' E.
Sun set 5A 2'.',,/.
Diffuse Light at 7 and 8 o'clock.
Clouds from last entry (22d) until this evening. Towards 7 o'clock, the sky cleared ; and, at 7'' and S1', had
good observations ; some haze and clouds along the horizon ; in consequence of which, could not get the outlines of the
Stronger Li<j,ht.
OBSERVATIONS ON THE ZODIACAL LIGHT.
147
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148 OBSERVATIONS ON THK ZODIACAL LIGHT.
No. 74.
OCTOBER 28th, 1853 :
Lat. 22=* 23' N.: Lon. 113 J 32' E.
Sun set 5A. 22m.
Diffuse LiL'ht at 6h. 30m. and "A.
Early part of the evening pretty good. Clouds prevented my getting the outlines of the Stronger Light; and,
spreading afterwards, stopped all observations at Y o'clock.
OBSERVATIONS ON THi; /
I.KJ11T.
149
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150 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 75.
(XTOBKU 29th, 1^53 : MOUSING.
Lit. 22 2.T X : L n II1! 32 E.
Run rosr fi'i (Urn
Diffuse Light at 2 nVlock.
Rose at fifteen ^I'IUKCS l>"ri>ve 2\ an } '.'• in 1 tlic sl<y ^retfy go > 1 for observations. At lh 50"", there seemed to be a
fiiint lilus>> of light rom Prfesope flown, lint not enough to be spoken of with certainty. At 2\ the light was de-
cided. ;i'vl :i.-; givi ;i :-i f' •<• "' art. At 2' 10'". t' r S r - i er Lig it, a' out llogulus, was equal to that of the Milky
\V;iy between Turc's aii'l 31 Cani< ?.';!] 'i''s. Moun rn:e ;ili,.nf 3''
OKSKRVATIONS ON TI1K ZODIACAL LIGHT.
151
152 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 76.
OCTOBER 29th, 1853: EVENING.
Lat. 22° 23' N. : Lou. 113° 32' E.
Sun set 5/i. 21Jm.
Stronger Light at Sh. 20m. Diffuse G/i. oOw.
6 30 70
70 8 45
8 41
Early part of the evening very clear, and made very careful and minute observations as follows : Sun set, by
watch, 5" 22m; 6h 13m, western sky one uniform, dead reddish color; 6" 20"1, sky lias become whitened — first below,
then the white ascending till it has the outline in the chart at that hour; 6h 23m, this whiteness, as if the lull moon
were at /3 Libras and going to rise ; 6h 25nl, it is now decidedly the Zodiacal Light (the Stronger Light), its limits the
same as at 6h 20'"; it is stronger and more decided towards Antares than at 6" 20m : 6" 27m, the Diffuse Light now spreading
out from the other, and ascending; 6" 30m, there has been all along from 6" 20m, a patch of light stronger than the
rest, as marked in the chart by the zigzag lines; 6" 33m, this patch scarcely seen (perhaps in consequence of being
lower toward the horizon); 6"45'n, the Stronger Light about 13 Bootis equal to that of the Milky Way between Alberio and
39 Cygni. Now, clouds stop observations; 7 o'clock, the clouds have shifted, and allow observations on the left; the
Stronger Light shows itself decidedly above the Milky Way; 8" 45m, it is now pretty strong there; 9h 30'°, the Zodi-
acal Light seems still to show itself above the Milky Way, but it is difficult to distinguish it from the general white-
ness of the horizon.
OBSERVATIONS ON THE ZODIACAL LIGHT.
153
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154 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 77.
OCTOBER 31st, Is.:,:; : MOKXIXO.
Lat. 220 23 N : Lon. H3° 32' E.
Sun rciM- l-li. lin.
Stronger LiyUt at o o'clock. Diffuse l/i. 40//i.
2 0
3 0
Sun's Longitude 218°.
Was on deck at lh 40'", when I found a faint appearance of liglit within tlic limits marked in the chart. It was
scarcely }ierce}itilile. At 2" the Light was decidedly Zodiacal. Again on deck at 3", when the Stronger Light was
also seen. Sky, now, clouded over; could get no further observations.
OBSERVATIONS ON T1IK ZODIACAL LIGHT.
155
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156 OBSERVATIONS ON T11E ZODIACAL LIGHT.
No. 78.
OCTOBER 31st, 1853 : EVENING.
Lat. 22° 23' N.: Lon 113" 32' E.
Sun set alt. 20m.
Stronger Light at 6h. 27m. Diffuse G.'i. 45w.
6 45 70
70 80
80 a 0
9 0
10 30
The atmosphere remarkably clear ; made careful observation. The twilight finally left a dead reddish horizon.
At G'1 22™ , this began to brighten and turn whitish, particularly under « and e Draconis; 6h 27™-, it is now decidedly
the Zodiacal Light; G'1 3CP, the Stronger Light (the only Light yet shown) has grown in strength very rapidly, and
is rapidly ascending; the Diffuse Light shows itself beyond the edge of the other; G'1 37m, there has been, from the
first, a patch of light (the same as last evening, and at the same place), stronger than the rest; but this is now gone,
and the Stronger Light is all equalized; for the rest, see the chart: (J:' 30'", presented the same appearance as 9K.
The atmosphere being unusually transparent (stars of the 6th magnitude very bright), I determined to watch assidu-
ously till nothing more could be seen. At 10h, the same as 9'' 30m ; but the inclination of the ecliptic has greatly
changed since 7 o'clock, and the Light (all the Stronger Light now) has shot across the Milky Way, and shows
itself in great brightness beyond ; H)'1 II)'", there was a change : the Light began to fade rapidly; 10h 30'", some of it
left, but quite contracted in limits (see chart) ; 11 o'clock, perhaps a little left, but nothing reliable, and no bounda-
ries can be got; nothing certain any more, and I cease observing.
OBSERVATIONS ON THE ZOOTACAT, I.lfJIlT.
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158 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 79.
NOVEMBER 1st, 1853 : MORNING.
Lat. 22^ 23' N.: Lon. 113° 32' E.
Sun rose 6h. 8m.
Stronger Light at 3li. Om. Diffuse-- at Ih. Om.
40 20
4 30 30
4 48 10
4 30
4 48
Sun's longitude 219° 6'.
The atmosphere being remarkably favorable, I determined to rise so as to be able to watch for the first indications
of the Zodiacal Light, in the cast. Accordingly was on deck at 8 minutes before 1"; but the Zodiacal Light was be-
fore me. There was already, from Pnesepe down, a narrow strip of blush or faint Light. Distrustful of my own
eyes, I got Lieutenant M (who had charge of the deck), to assist me with his judgment; and he agreed that
there was a degree of light there, which the adjacent parts of the sky did not have. The boundaries are given in the
chart. 1 remained on deck till 2", and saw this faint tinge gradually increasing in strength, and widening its bor-
ders, till it became at 2'1 as in the chart. Rose again at 3h, and found the Stronger Light showing itself. From 4h
to 4h 30"', the Stronger Light was really splendid. It was as if the sun were going to rise there, in a minute or two.
At 4h 30m, it suddenly began to lose its brilliancy, and to sink clown very rapidly. Its limits, at 4h 30m and 4" 45m, are
given in the chart. At 4'1 50m, the light broke bounds and spread laterally with great rapidity ; at 4" 52'", there were
-no boundaries, the eastern sky had all a general whiteness, and dawn bad arrived.
OBSERVATIONS ON THE ZODIACAL LIGHT.
1-59
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160 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 80.
NOVEMBER ls>t, 1853 : EVENING.
Lat. 22° 23' N.: Lon. 113° 32' E.
Sun set 5A. 19«.
Stronger Light at 7/i. Om. Diffuse, 1h. Om.
80 80
90 90
10 0 10 0
11 0
There were clouds (cirri) in the west till 7 o'clock, when they left, and I commenced observations ; the atmosphere
remarkably clear quite down to the low hills which lormed the horizon. Determined, as circumstances were so fa-
vorable, to watch it to the last; and also to see its first beginnings afterwards in the east, so as to know how near,
in time, the eastern and western Zodiacal Lights approach each otl.er. The evening result is in the chart. After
10 o'clock the Diffuse Light faded into nothing; at llb, the other had become very taint, but was still perceptible.
This lasted till 11" 30m, when there was nothing any longer reliable; nothing certain to distinguish that part of the
sky.
OBSERVATIONS ON T1IE ZODIACAL LIGHT.
161
102 OBSERVATIONS ON TUB ZODIACAL LIG11T.
No. 81.
NOVEMBER 2d, 1853 : MORNING.
Lat. 220 93' N.: Lou. 113° 32' E.
Sun rose GA. 9>n.
Stronger Light at O/i. 50m. Diffuse 4A. Om.
40 4 30
4 27
4 41
4 49
Sun's longitude 220°.
Was on deck at midnight, to watch for the first indications of the Zodiacal Light. Prassepe was above the horizon,
but the sky below it was like every other part; watched closely, but could see nothing till half an hour past mid-
night, when 1 thought there was possibly a little tinge of white, but was doubtful; 12h So"1, thought the tinge had
increased, but was still doubtful; 12" 40'", the light, pretty reliable as the Zodiacal Light. At 12" 50'", I called the
quartermaster on duty, and, pointing to a stretch of about 90° along the horizon, said: "Does any part of that sky
appear brighter to you than the rest?" He answered immediately, pointing to the portion below Prajsepe, " Yes,
sir, it is considerable brighter just here." Tlhis was also my own opinion. So between the disappearance of the
western, and the appearance of the eastern Zodiacal Light, in reliable forms, there was an interval of 80 minutes.
For the rest, see the chart. At 4'' 25°', the Stronger Light, suddenly sunk (in two minutes' time), and at 4h 2'7m,
was as in the chart, being also much diminished in brightness. At 4h 40"', it widened rapidly below ; at 4h 49m,
was as in chart. At 4'1 50"', the light broke bounds effectually, and spread over the sky; at 4h 52'", dawn had fully
come.
OBSERVATIONS ON THE ZODIACAL LIGHT.
163
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154 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 82.
NOVEMBER 3d, 1853 : EVENING.
Lat. 22° 23' N.: Lon. 113° 32' E.
Sun set 5A. 18Jm.
Stronger and Diffuse Light at 7/i. Om.
8 0
9 0
10 0
Determined again to watch the Zodiacal Light till its entire disappearance ; but, a little before llh, the sky became
clouded in patches, which prevented my getting boundaries from that time on. The light, however, could be seen
between the clouds (made even more striking by them), until 11" 45ra. The quartermaster on watch, in answer to a
question from me, said, at once, that the sky was brighter there (i. e. about /? Aquarii), than in the other parts of
the sky.
The clouds lasted till dawn.
OBSERVATIONS ON THE ZODIACAL LIGHT.
165
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166 OBSERVATIONS ON THB ZODIACAL LIGHT,
No. 83.
NOVEMBER 4th, 1853 : EVEXITO.
Lat. 22° 23' N. : Lon. 113° 32' E.
Sun eet 5A. 7Jm.
Stronger Light at Sh. 20m. Diffuse 8A. 20m.
90 90
10 0 10 0
11 0
Sun's longitude 222°.
Clouds in the morning, and moon in the evening till 8h. Got observations then, and till llh, at which latter time
clouds had commenced floating up, so as to cover part of the Zodiacal Light; no further reliable observations could
be had. At 9", the Stronger Light at 56 and 57 Sagittarii, was equal to that of the Milky Way about 16 Vulpis.
OBSERVATIONS ON THE ZODIACAL LIGHT.
167
168 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 84.
NOVEMBER 5th, 1853 : EVENING.
Lat. 220 23' N.: Lon. 113° 32' E.
Sun set 5h. 17m.
Stronger Light at 9A. Om. Diffuse 9/>. Om.
10 0 10 0
11 0
Sun's longitude 223° 1'.
Clouds in the morning. Moon this evening set a little before 9b; got observations from that time on. Evening
clear and good for work. Worthy of notice, how, as the evening advances, and the ecliptic increases its angle, the
Light shoots upward, narrowing its cone. At 12h, the ecliptic is nearly perpendicular to the horizon.
At llh, the Diffuse Light seemed to have the same boundary as at 10h, but I could not determine reliably. Thought
that the Stronger Light could be made out till 11'' 30m; by which time, however, it had become so low down, and so
mixed with the whiteness at the horizon, that I could now no longer speak of it with certainty. The existence of the
Diffuse Light at IP 30m, could also not be affirmed with certainty.
OBSERVATIONS ON THE ZODIACAL LIGHT.
169
170 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 85.
NOVEMBER 8th, 1853 : MORNING.
La,t. 22^> 23' N.: Lon. 113° 32' E.
Sun rose 6h. 12m.
Stronger Light at 2A. lam. Diffuse 2/i. Om.
30 30
40 40
4 20
4 27
Clouds since last entry (5th). Eose this morning at 2h, and had observations thence on till twilight. Morning
favorable. The Stronger Light began to be reliable at 2" 15m (rather suddenly). At 4h 15'", this Light was very
strong ; but at 41' 20'", it suddenly sunk to 77 Leonis Majoris, and at the same time was greatly dimmed. At 4h 24m,
it began to brighten again, and to expand below; and at 4'1 27'", its limits were as in the chart. At 41' 50™, it had
brightened again considerably. At 4h 5G'", it broke bounds, and at 4h 58m dawn had arrived.
OBSERVATIONS ON TIIF, Z'U>IACA1, LIGHT.
171
172 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 86.
NOVEMBER 22d, 1S53 : EVENISO.
Lat. 22° n- y,: Lon. i13o 3C- E.
Sun set 5//. llAin.
Stronger and Diffuse Liglit at 7 o'clock.
Clouds constantly since last entry (8th). This evening at 7", had an observation ; sky pretty clear. At 8", clouds
had intervened ; I got no further observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
173
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174 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 87.
DECEMBER 5th, 1S53 : MORXISO.
Lat. 22= 11' X.: Lon. 113= 30' E.
Sun rose C/i. 2Hm.
Stronger Light at 1A l.jm. and Ik.
Sun's longitude 253J 19'.
Cloudy from 22d ultimo to tins date. Rose at ten minutes before lh. At 1 o'clock tVre seemed to lie a liIusTi of
light in the sty, from Kegulus down. Should not have doubted it, if there had not been a similar kind of blush
along the horizon from this place to the Milky Way, on the right. At T1 12'", took outlines, but do notl'eel perfectly
satisfied about the character of the Light. At lh 37"', it seemed to be pretty decided. At 2'', scarcely a doubt about
it. There would have been none, it' it had not been for this blush, still on the right; but this latter did not extend
upward, like the other. At 3'', the sky has all clouded over once more.
OBSERVATIONS ON THE ZODIACAL LIGHT.
175
I!
1"
Er
--]
176 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 88.
DECEMBER 21st, 1853 :
Lat. 23- i' N.: Lon. 11.V 2«' E.
Sun fct 5A. Ifijw.
Stronger Lis;lit at fi/i. 30/n. and 7A. Diffuse 7/1.
Clouds since last date till tins evening, when I succeede;! in having some ^mxl observations, for which see the
chai't. Cl'J1i Is immediately alter spread _ver the sky, and prevented further observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
Eg r
ll
-='--
178 OBSERVATIONS ON TUB ZODIACAL LIGHT.
No. 89.
DECEMBER 23th, 1?53 : EVENING.
Lat. 22- IS' X : L<m. Ill- 10' E.
Sim si.-t .')//. 22«i.
Stronger and Dijusc Ll^lit at ~h. Om.
7 30
8 0
9 0
Sun's lon^tu.L- 27U- it'.
Clouds uniformly since last date until to-day. This evening, sky jr-i-re^ly ck-ir. Tho planet Venus interferes
somewhat with observations, bat »;ij id outliiu-i i-.in still b i [iro. •!!•,• 1. At :')';! I ', t'iL' Z > li ml Li^'it discern ible, but
faint; 0" 38", stronger, but too dim to give ivliabl.- nudiius. At 7", ^ >\- outlin >s >;'b >t'i Diffuse and Stronger Li^bt,
but tlie former Li»-ht was dim. For the rest, see chart. At 10'', the Diil'i-i" Li ;!it still to bj se 'ii, its outlines the
same as at 91'; no Stronger Light to be seen. At 11", there seemed to be some Light lel't, but nothing reliable.
on.sEUVAfross <>NT Tin: /o:>iAr\i, I.HIIIT.
179
'23
OBSERVATIONS ON Til K 20MAUAI, LIGHT.
No. 90.
DECEMBER 29th, 1S53: MOEXIXO.
Lat. 22" 18' N. : Lon. 1H° 10' E'.
Sun rose 6h. 42m.
Stronger Light 3lt. 30m. Diffuse 3/i. low.
40 40
50 50
5 25
Sun's lou;itude 279° 45'.
Eose a little before 3h. Atmosphere remarkably clear, and morning very fine. Observations as in the chart. At
5h 25m, the Stronger Light sunk suddenly down from the limits marked for 5h, to those marked 5h 25m, in the chart.
At 5h 31m, it broke bounds and spread, and dawn had come.
OBSERVATIONS ON TI1K ZODIA(\\I, l.TCIIT.
IS!
OBSERVATIONS OX THE ZODIACAL LIGHT.
No. 91.
DECEMBER 20th, 1853 : EVKMNG.
Lat, 223 IS' N.: Lon. IIP 10' E.
Sun set 5A. 23m.
Stronger Light at 1h. Om. Diffuse Git. 4am.
7 15 7 15
7 30 7 30
S 30 S 30
9 30
Atmosphere remarkably clear. Sky unclouded. Watched to see how the Zodiacal Light would first show
It came so gradually that nothing belonging to it could be made out, till at 6h 30'", it was evident that the .sky along
its place had paled somewhat. The twilight is long, and at G1' 35™ darkness had not fairly set in. But the Zodiacal
Light was faintly marked in the sky, even before the stars were all fully out. The Light was not strong enough to-
give boundaries till 6h 45m, when I got those of the Diffuse Light; the Stronger did not show itself distinct from the-
other till 6" 55m ; at 7'1, I got its boundaries. For the rest, see the chart. The Light was brightest at about 7" 3CP.
The Stronger had dimmed at 8h SO1", but was yet good. At 9h 30'", there was no Stronger Light as such; but the
Diffuse was very bright, the Stronger seeming to have spread into this. Exhausted by last night's watching, I
now went to bed.
oliSl -UVATIONS >N TI1K ZODIACAL I.1CIIT.
183
I J \0 I J 7[0 / J
i i i . i-i~i~H'i i -i i rr'TT'i I-.T-I I v •> "rrl . < > i
184 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 92.
DECEMBER 30th, 1853 : MORNING.
Lat 22-' IS' N.: Lon. 11-P 10' E.
Sun rose 6A. 43m.
Stronger Light 3/i. Om. Diffuse 3h. Om.
3 30 3 30
4 30 4 30
5 20 Paled sky 4 30
5 25
Sun's longitude 278° 47'.
Morning sky fine and clear. Intended to b? up at 1" SO"1, but was not waked till near 3'1. Took boundaries as in
the chart. At 3", the Stronger Light was faint, the Diffuse very distinct. This last, at all this morning's observa-
tions, seemed to run up to Prresepc, coming nearly to a point there: but I could not be certain about it, and have
put ? to the doubtful lines. The Zodiacal Light was strongest at about 4" 30:". At this hour (4" 30'"), I was sur-
prised to find that the Diffuse Light on the left, or north, had greatly extended its boundaries, running through the
middle of Corona Borealis. I have, for that hour, given, with the Stronger and the Diffuse Light, also this latter ex-
tension, marked by dots andaaa, though it \vas so strung as t:> be very little different from the Diffuse Light itself. I was
not looking lor this; but I now remember a similar sudden extension, northwardly, in the evening Light of the 1st
of July. Tins is in the same part of the sky. and is probably owing to the same cause — namely, that the approach
of the ecliptic to the horizon brings this nebulous substance more laterally to the eye. There is now. between mid-
night and 5 o'clock, a great lessening of the angle of the ecliptic with the horizon, particularly towards 4 or 5
o'clock. This extended light is, however, much stronger than that of July, when first seen; being, in this respect,
the opposite of that. This extended light seems to reach up to Prassepe ; but as the space between Regains and
Prsesepe is quite void of stars above those of the 6th magnitude, I am doubtful of it. Still, there does seem to be a
positive whiteness, as of the Zodiacal Light. From 5'1 20" to 5h 25"', the Stronger Light sunk rapidly down, and was
very much dimmed. At 5h 32'", the Light broke bounds and spread, and dawn had come. This spreading, however,
is not so striking as it was in September and October.
OBSERVATIONS ON TI1K ZODIACAL LIGHT.
185
186 OBSERVATIONS ON THE ZODIACAL LIGUT.
No. 93.
PF/'KMBEU ."Oil). ]s.~>:! : ICvrxixn.
L
;il 'JJ IS' N.: L'.n. Ill'
10'
Sun srl, ;V/. 2 \in .
C?(
.•]• Liybt at (i/i. 4o/». l.'ill'
•isr li
:/. -jr.™.
7 li
7
20
7 45
j
45
S 0
S
30
S f!U
y
:;•>
11
30
Mi
InigU
\1
30
1
Q
2\
A mn:;' f;ivi inside iiinc. Atmosphere perfectly clear, and sky good down to the horizon. Victoria mountain (Hong-
Kong) interferes a little, but not so as to produce any difficulty. I determined to watch this night through, in
order 1- see nil the changes of the Zodiacal Light, and to discover how long it would last in the west, and how soon
it would appear in the eastern sky. The ecliptic, at this time, is most favorable for the endurance of the Light,
belli;;- nearlv vertical to the horizon at midnight, so as to give as little trouble as possible from haziness or the ordi-
nary glare along the horizon. I was well rewarded to-night, having had the rare satisfaction of seeing the Zodiacal
Light at once, at the east and west, at 12 o'clock. The following are my notes : "At 6" 30m, twilight not quite past,
and the stars imperlectly out; but the Milky Way is clearly distinguishable, and so also is the Zodiacal Light, though
the latter is dim. I tried to get its boundaries; but after succeeding in-one or two spots, had to give it up, the Light
being so faint as not to give reliable outlines throughout. At 6h 42"1, succeeded; 6" 45m, could get outlines of Stronger
Light. Observations from this on, as in the chart. The Stronger Light was strongest at 7" 45m ; by 8" 30'" it bad
become dim. At !>'' 30'" Stronger Light almost gone; it has ascended, and widened into the Diffuse, which is now
very distinct and bright — brightest at its lower end. At 11", quite distinct, as high as the Pleiades, its limits nar-
rower than before, and running up cone-shaped: brightest at lower end. It perhaps extended up as far as 123
Tauri (tip oE the horn), but I was not certain; it rather seemed so to me. At 11" 30"', Light still visible, but dim.
Thought, then, it <li<l extend up to 123 Tauri. Boundaries as at 11". It was now simply a paling of the sky. At
midnight, still a paling of the sky; boundaries as at 11"; it is, however, scarcely perceptible. Now saw theZodiacal
Light also in the cast, for which see morning chart of December 31st, and remarks. At 12" 30'°, the western Light still
seemed to continue; its boundaries as hH'orfc, ^ It was as bright as the extreme edge of the Milky Way, just by
Gomeisa, but has a warmer tint than the Milky Way. At I'1, it still seemed to be visible — appeared not io lie
out, but to be sinking with the Pleiades; its limits as before. At 2h, it had quite gone."
OBSERVATIONS ON THE ZODIACAL LIGHT.
187
c- -
in
I HI
t-m
1=3
I a
= 3
_==!
ja
24
188 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 94.
DECEMBER 31st, 1853 : MOUSING.
Lat. 22^ 18' N.: Lou. 111° 10' E.
Sun rose GA. 42m.
Stronger Light ih. Om. Diffuse at Midnight.
5 0 0/t. 30m.
5 22 10
S 25 20
4 0
5 0
At 12" (midnight) turned from the west, where the Zodiacal Light was still visible, and found it showing itself
also in the east. Distrustful of my own eyes, I called the quartennnsler on watch, and, directing him " to draw a
line hy two certain stars" (Regulus to Mars), said: "Tell me whether the sky looks paler to you along that line,
and a little on either side? Look for some time." lie soon replied : "Yes, sir, it looks paler and dim." I said :
"How far up?" He replied: "To that bright star" (Regulus); but thought it might be to the dim cluster above
(Prresepe)." Which latter was also the limit, as it appeared to me. At oO minutes past midnight, seemed to be a
little brighter; same limits as before. At 1 o'clock (he Light was quite distinct; not simply a paling of the sky, but
a positive light. At 21' 30"1, Light increased — quite strong from 29 Virginia down. Soon after 5", the Stronger
Light began to descend rapidly, as the chart will show, till it rested as marked at 5'' 25m; at 5h 32m, broke bounds,
and dawn had come.
OBSERVATIONS ON THE ZODIACAL UGIIT.
189
190 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 95.
JANUARY 2d, 1854: MORNING.
Lat. 22? IS'N.: Lon. 114= 10' E.
Sun rose 6/1. 43m.
Stronger Light 2A. Om. Diffuse OA. 30m.
30 10
40 20
50 30
5 10 40
5 25 50
"Western Zodiacal Light Oh. 15m. and 1 o'clock.
The evening of the 31st was cloudy ; yesterday was Sunday. This morning I was on deck a few minutes after
midnight, and found the Zodiacal Light, both in the western and eastern sky, as on the 31st a. m. As regards the
west-.rn, took outlines at 0" 15"' ; the Light was very dim; I thought that between « and co Arietis, it 'was equal to
that of the Milky Way about cr, ", and to Andromedse. At 12'' 30m, it seemed to be more decided than the Zodiacal
Light in the eastern sky, but this was probably not real. At I1', it could still be seen; its limits, as in the morning
chart at 12" 15m. At 2'' nothing of it left. Query — does it die out, or remain to sink under the horizon? To-night
I thought the former. The Pleiades, its upper end, were, however, approaching the horizon at 2 o'clock, and its
disappearance might have been owing to the horizontal haze or dimness.
The night was a most favorable one; stars were bright ; scarcely a breath of air stirring.
At 12'' 10'", there seemed to be a dim Zodiacal Light in the eastern sky. I was not then fully decided about it,
but, as afterwards I saw it gradually growing into the certain Zodiacal Light, of which at 1 o'clock there could be no
doubt, I felt satisfied that this at 12" 10'" was truly that Light. At 2h the Stronger Light was decided enough to
give boundaries. For the rest, see chart. The sinking of the Stronger Light at 51' 10m, was remarkable: — it was so
sudden, as was also the change in the strength of the Light. At 5h I was admiring its brilliancy, and thought it
was stronger than at any previous time that morning; just before 5h 10"", it began to sink, and in two minutes' time
had got to the limits given in the chart (marked 51' 10'"), and had lost more than half of its intensity : it was, indeed,
now rather dim. At 5" 25m, it had got still lower — same strength as at 5" 101". At 5h 33'" dawn had come. While
the Stronger Light was changing thus, the Diffuse remained the same as before, both in strength and boundaries.
[P. S., lS5fi. — I had prepared my chart with both the eastern and western Zodiacal Light upon it, at 12" 15"' and
I o'clock, but find it impossible to enter it in this bunk. The vertices of the eastern and western Lights were then 75°
apart, not cusp-shaped, but rcmnded upwardly. The western Light extended to the Pleiades, and at its base reached
1^° N., and 15° S. of the ecliptic.]
OBSERVATIONS ON THE ZODIACAL LIGHT.
191
192 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 9fi.
JANUARY 2J, 1854 : EVENING.
Lat, 22= is' if. : Lon. 114=> 10' E.
Sim set 5A. 24m.
Eastern Zodiacal Light at 11A. 30m. and midnight. Western Stronger Light 8h. 30m. Diffuse 8h. 30m.
9 30 9 30
in 30
Midnight
1 0
Moon till about 8h 30m. At that hour got observations. The night remarkably fine, sky clear, atmosphere trans-
parent, no wind. At 9h 30"1, the Stronger Light was dim, but I was able to get boundaries. At 10h 30m, it was gone;
11" 30"', boundaries same as at 10" 30m. At 12h (midnight), the Light was dim, but still distinct. Between a and 73
Arietis, along on the ecliptic, the Light was equal to that of the Milky Way adjoining Betelgucnx. At 11" 3CP, saw
also the Zodiacal Light in the east, for which see morning annotations, and also its boundaries in the evening chart.
At 12", the Light in the east and west was about equal. At 1 a. in., the western Light still visible, but scarcely to
be made out ; its boundaries as at 12h. At lh 45'", nothing of it to be seen. It dies out; for the space below the
Pleiades, at, this hour, was free from haze quite to the horizon, yet was dark like the rest of the sky.
= 59
= a
5 a
I
il
eft
Efe
194 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 97.
JANUARY 3d, 1854 : MOKMNII.
Lat, 22^ is- K.: Lou. 114° 10' E.
Sun rose GA. 43m.
Western Zodiacal Light at midnight and 1 o'clock. Eastern, Stronger Light at 2 A. Om. Diffuse ll/i. 30m.
3 30 Midnight
4 30 10
55 20
5 10 3 30
4 30
5 10
As mentioned in the annotations of last evening, the eastern Zodiacal Light showed itself at half an hour before
midnight, very faint, but still visible. Its northern limits were easily made out, but there was a dilliuiilty iu getting
those towards tlie south; also it was difficult to say where it terminated above. At 12", it was as bright about 77
Leonis Majoris (a a in the chart) as the Milky Way close to Betelgueux. At 1", it was more distinct, but still dim.
The night was remarkably favorable for observations. The Stronger Light showed itself at 2'', but was dim. I was
puzzled all through the morning's observations, by what seemed to be a narrow streak of the Diffuse Light, bounded
by Pollux on one side, and the ecliptic on the other, and continued above Pnesepe, seemingly to the Milky Way.
But this was all very uncertain. Still it forced itself on my notice again and again. I did not know what to make
of it. It seemed to be, and seemed not to be. Between 5" 5'" and 5" 10'", the Stronger Light dropped down as shown
in the chart. I watche'd it as it evenly but rapidly sunk; what remained also losing half its late brilliancy. After
this, there seemed to be pulsations in the strength of this Stronger Light; it kept its boundaries as at 5'' 10'", but
seemed to increase and to fail in strength at intervals of five minutes or so; never, however, getting to the intensity
which it had just before 5" 5m. Dawn at 6" 30'".
OBSERVATIONS ON TMK ZODIACAL
195
196 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 98.
JANUARY 3d, 1854 : EVENING.
Lat. 22^ 18' K.: Lon. 114^ 10' E.
Sun set 5A. 25m.
Eastern Zodiacal Light at 11A. ZOm. and midnight. Western, Stronger Light at !)/;. 40m Diffuse 9A. 20?n.
10 0 10 0
Midnight
i o'clock.
•
Moon interfered till some time after nine. At 9h 40°" got observations. Night a most favorable one, calm and very
clear; sky brilliant. For observations, see chart. At 12h (midnight), the Light was still very decided in the west —
quite distinct. At I'1 a. m. there was the slightest possible tinge; same boundaries as at 12h. At lh 23m the western
Zodiacal Light was still visible, but very faint; no boundaries could be got. At lh 32m it was gone. There was then
a slight haze along the western horizon, but not high; and there was no light between it and the Pleiades. The
.Zodiacal Light had evidently died out.
At II"1 1 turned to the eastern horizon to observe there also. My notes are as follows: ''At llh, there seems to be
a faint tinge in the eastern sky, as high as Prsesepe, and with the usual Zodiacal Light boundaries ; but cannot
speak positively — not certain. At llh 20m, I think I can speak positively; got boiindaries; llh 30", it seems to be
quite certain; the Light about Mars — i. e. above TY and 78 Leonis Majoris — is equal to that of the Milky Way close to
Procyon, but has the warm tinge of the Zodiacal Light; the western Light is of the same strength; llh 40m, the
eastern Light is certain now; it is stronger than that in the west." All this gradual growing, with the certainty
at llh 40™, makes it, I think, sure that I saw it at 11 o'clock. As the western Light continued till lb 23° a. m., both
eastern and western Lights were, consequently, simultaneously visible for two hours and twenty-three minutes.
198 OBSERVATIONS »N THE ZODIACAL LIGHT.
No. 99.
JANUARY 4th, 1S54 : MOUSING.
Lat. 22° 18' N.: Lou. 114° 10' K.
Sun rose 6/1. 44m.
Western Zodiacal Light at midnight and 1 o'clock. Eastern Stronger Light l/i. 40m. Diffuse I1A. Wm.
2 30 Midnight.
40 10
55 2 30
5 10 40
5 IK 50
6 20
The western Zodiacal Light continued until lh 23m of this morning, as is noted in the evening record of January
3d. The eastern Zodiacal Light began to appear at IT, though it was but a very faint tinge. I was doubtful of it;
but having watched it as it increased in brightness, till at llh 40'° there could be no doubt of it, I think it may be
considered certain that it was seen at 11 o'clock. Took boundaries at IT 20m, &c., as in the chart. As the morning
advanced, the Stronger Light seemed to slide to the northward, and it will be seen from the chart that the inclination
of the ecliptic to the horizon was then diminishing very rapidly. After 5h 5m, I was looking at the Stronger Light,
and, not aware that the minutes had passed so rapidly, was not expecting any sinking of the Light yet ; when I noticed
suddenly that it was no longer in its late position, but had sunk to c c; on looking at my watch, I found it was the
time for it; it was now 5h 10'°. It had also but half its late intensity. This diminishing in height and intensity
could have occupied little more than a minute. At 5" 16'" it had got clown to b b. Then, very soon, it began to
ascend, also brightening up, till it got one-third of the way from b b to Spica, when it sunk rapidly again, and at
5h 20m had got to the position given in the chart, a a, also dimming again; thence it rose once more to b b, and at
5° 26m had sunk again to a a, brightening and dimming as before; then it ascended once more to b b, brightening
as it rose; and at 5" 31m it was down again to a a. At 5h 32m the light broke bounds, and dawn had arrived. In
these pulsations, the increase in height and strength of brightness was much slower than the decrease.
I ought to remark, that, although from 4h 30" to 5 o'clock, the Stronger Light is quite strong, it has never the great
brilliancy of the morning Light in September and October. This will apply also to the intensity in the present
evening observations.
ORSKRVATIONS >N T11K ZODIACAL LIGHT.
109
200 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 100.
JANUARY 5th, 1854 : MORNIKO.
Lat. 22° IS' N. : Lon. 1140 10' E.
Sun rose at 6I>. 44m.
Western Zodiacal Light at 11A. Om. Eastern, Stronger Light l/i. 0m. Diffuse 11A. Om. Paled sky at 1A. 25m.
Midnight. 1 30 Midnight. 5 0
10 30 10
4 45 1 30
3 0
5 0
The moon did not set till about 11 o'clock. At that hour got an observation in the west, and found the Zodiacal
Light also quite decidpcl in the eastern sky. At llh lom the western Zodiacal Light between « and 78 Arietis was
equal to that of the Milky Way at 51 and 54 (right foot) Andromedre, but it was of a warm cast. The eastern
Zodiacal Light was of about the same strength. At 12h the boundaries were as before, but the Light was dim. At
lh 5m it was still distinguishable; at lh 20m all was gone.
[P. S., 1856. — The want of room in the chart here given prevents my giving the boundaries of this western Light
noted above. It extended as high as Aldebaran, and'at the western horizon, at midnight, reached 16° S., and 23°
N. from the ecliptic. The vertices of the eastern and western Zodiacal Lights at 11 and 12 o'clock were 51° apart.]
The eastern Zodiacal Light was quite decided at 11 o'clock last evening; its strength is referred to above. At
12h (midnight), it was still the same; took boundaries also at 1" and lh 30". At 1" 25'" and lh 30'" the sky was paled
to the dotted line. Got the Stronger Light at I1' and lh 30"1. I meant to get boundaries at 4h, but slept so soundly
that the orderly's call did not rouse me till towards 5". At 5h there was a paled sky beyond the Diffuse bounds, of
which I have given limits in dotted lines. Above the limits of the Diffuse Light, as given at 5h, there seemed to be a
strip of paled sky; could not see how far up it went. At 5h thin clouds came floating over, and stopped reliable obser-
vations. I could see between the clouds that the Stronger Light sunk, and seemed to pulsate, as yesterday morning.
At 5h 15m, as the clouds were obstinate, and would not admit of any definite results, I left the deck.
/= =
202 OBSERVATIONS ON THE ZODIACAL LIGUT.
No. 101.
JANUARY Cth, 1854 : MOEXIXG. »
Lat. 22° 18' N. : Lon. 114° 10' E.
Sun rose G/t. 30m.
Western Zodiacal Light at 11A. 45m. Eastern, Stronger Light l/i. Om. Diffuse 11A. 45m.
40 10
4 0
Moon did not set till very late. At llh 45m got observations ; Zodiacal Light still in the west, as per chart. At 1"
clouds prevented observations in that direction. At llh 45™ got boundaries also in the east; so also at 1 o'clock,
together with Stronger Light. Clouds at 2h. At 4" got observations as in the chart; while finishing them, the sky
was clo'uded over; so it remained till dawn.
[P. S., 1856. — My space here is too contracted to allow my inserting these western boundaries. In my original
chart they reached within 2° ot Aldebaran, and at the base extend to 17° N. and 15° S. of the ecliptic. The dis-
tance between the vertices of the eastern and western Lights at llh 45"1 was 58°. These vertices are not cusp-shaped.]
OBSERVATIONS ON THK ZODIACAL UGUT.
203
II
a
M
sr-
B£---
f-;r
mm
ma
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•B
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= r"ir
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Bjgf
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26
204 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 102.
JANUARY 10th, 1854 : MORNING.
Lat. 22'^ 18' N. : Lon. 114° 10' E.
Sun rose 6A. 46m.
Stronger Light at 3h. Om. Diffuse 3A. Om.
40 40
60 SO
6 5
6 7
5 12
5 10
Clouds since last date (6th). Moon set just before 3 o'clock. At 3", &c., had observations, for which see chart. I
watched very carefully at 3", 4h, and from 5h on, to see if there were any pulsations. Nothing till after 5h. At 5"
the Stronger Light was very bright, and extending up to Spica, though dimmer at its upper end ; at 5h 5m it had sunk
to a Libra?, and had become greatly dimmed ; had about half its former brightness. At 5'1 7m it seemed to have
ascended about 9°, and to have brightened some ; at 5" 12m it was down to 38 Libra?, and had dimmed; it perhaps
rose a little again, but of this I was not certain. At 5'1 19'" it was down to ft and 6 Scorpionis, and had spread to
the northward ; it was now bright; at 5" 23™ the light broke bounds, and dawn had come.
These risings and sinkings, and changes of intensity, are as they appear to me to be; but the upper limit of this
Stronger Light is so indefinite, and the changes are of such an indefinite character, that I wish to speak of them
somewhat doubtingly. Of the first sudden sinking and loss of intensity, I think, however, there may be no doubt.
The morning was remarkably favorable for observations; atmosphere clear, sky very bright, and very little haze
on the horizon.
In September 2d, and October 4th, of last year, are notices of an increase of the Zodiacal Light after the first
dimming. I remember noticing, not imfrequently last year, an .apparent ascent of the Stronger Light after its sud-
den subsidence, and also, with this, an increase of light; but there seemed to be more uncertainty attending its
character, and I believe I have neglected to take note of it.
OBSERVATIONS ON THE ZODIACAL LIGHT.
205
t =
ES
-''-'•'
206 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 103.
JANUARY llth, 1854: MORNINS.
. Lat. 22° 18' N.: Lon. 114° 10' E.
Sun rose G/i. -tOm.
Stronger Light at 4A. Om. Diffnso 4A. Om.
4 40 SO
5 0
5 2
6 7
5 12
5 14
6 16
Moon did not set till almost 4 o'clock. At 4h got boundaries; and also at 5h, as in chart. After 5h, was carefully
on the watch to see if there would be any pulsations. Morning very clear. Atmosphere transparent; every thing
favorable for good observations. My notes run thus: " 4h 40'°, Stronger Light very strong and bright; 5h 2m, it h'as
sunk, and has dimmed; 5h 7™, sunk lower, dimmed to half its former brightness; 5h 12m, has risen, and has just sunk
again (for its latter place, see chart); 5" 14"1, up again, and has brightened; 5h 16m, is up now to « Libras ; 5h 22ra,
breaks bounds, and dawn has come. In breaking bounds, it spreads first and most rapidly towards the north ; then
southwardly." These are my notes — for so it seemed to me; but, after all, these pulsations may only be seeming
ones. I do the best I can, in watching carefully, and recording what appears to be. One thing I can say with cer-
tainty: namely, that there is first a sudden and very rapid sinking down of the Stronger Light, with a dimming to
about one-half of its late intensity; and then, a little while before dawn, a rising again of the Stronger Light, with
an increase of brightness, though not coming up to its former strength. Of so much I can be positive.
This morning I concluded to watch after dawn had come ; for the Light, though spread over the whole eastern sky,
was yet strongest at the central line of the late Zodiacal Light; as if, while the sunlight had now reached our atmo-
sphere, and was reflected from it, the reflection was still strongest from the substance giving the Zodiacal Light. At
51' 25m a little of this was still left — say from 38 Libras down; 5h 28m, some slight trace of it still remained; 5b 30™,
all gone ; sky uniform .
All this corresponds conversely to the first appearing of the Zodiacal Light in the evening sky, as I have often
described it; the time when I suddenly become conscious that I am looking on the true Zodiacal Light, corresponding
to the morning period just before the time when the Light breaks bounds, and becomes mingled with the dawn light —
i. «. light from our atmosphere.
OBSERVATIONS ON THE ZODIACAL LIGHT.
207
208 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 104.
JANUARY 18th, 1854 : EVENING.
Lat. 23? 40' N : Lon. 123" 28' E.
Sun set 5A. 33m.
Stronger Li=;lit at Git. 30m. and Ik. 30m. Diffuse 6h. 40m. and Ih. 30m.
Clouds since the llth until this evening. To-night was able to get brief, but fair views of the western sky, and
had observations at G1' SO1" and 7" 30m. Soon after this, the moon rose. Was watchful to try to get moon Zodiacal
Light, but clouds overspread the sky just before the time, and I was disappointed.
OBSERVATIONS ON THE ZODIACAL LIGHT.
209
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210 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 105.
JANUARY 24th, 1854 : EVENING.
Lat, 26° 10' N.: L.m 127- 42' E.
Sim set 5h. 33m
Diffuse Lifcht at 7/i. 39m,
Loo (7/100. — Clouds since the 18th, except Sunday evening. This evening, in a brief interval between the clouds,
got an observation at 7" 39'"; could get no more. The sky is almost constantly covered with ever sliiftiny clouds.
OBSERVATIONS ON TUB ZODIACAL LIGHT.
211
27
212 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 106.
JANUARY 25th, 1854: EVZXLNO.
Lat, 26° 10' N.: Lon. 127° 42' E.
Sun set 5h. 33t m.
Stronger and Diffuse Light 7A. and 7A. 43/n.
A most changeable sky ; at one time large portions of it are clear, and then, immediately after, it is covered all
over with clouds. Watched for clear intervals, and got two observations as in the chart ; the western speck of the sky,
at these times, was ivmarkahly clear. At 7" 50'" the Stronger Light was very bright, indeed, at the spot marked a a a
in the chart; and below this, it was brighter than any part of the Milky Way then above the horizon. The sky was
clouded over immediately alter 7'1, and I could get no further observations during the night.
OBSERVATIONS ON TUB ZODIACAL UGUT.
213
1!14 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 107.
JANTJAEY 26th, 1854: EVEMKO.
Lat. 26° 10' N.: Lon. 127^ 42' E.
Sun set 5h. 3Jm.
t 8h. Om. 1
Stronger Light J !) 0 -Diffuse, Sh. and 9A.
0 30
Blowing half a gale, as it has been ever since our arrival at Loo Choo. Now and then are openings to a clear sky;
and at such intervals, this evening, I got observations of both the Diffuse and Stronger Light. At 8h, this Stronger
Light was very brilliant; just as if the sun were going to rise at that part of the sky. It is now much brighter
than for a long time past. At 9h, it was considerably dimmed. Might, perhaps, have got observations to a later
hour ; but as the Light then, on account of its dimness, would have required a good sky in order to get boundaries
reliably, I made no further effort.
OBSERVATIONS ON TI1E ZODIACAL L1G11T.
215
216 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 108.
JANUARY 27th, 1854 : Jloim.va.
Lat. 26^ 10' N.: Lon. 127342' E.
Sun rose tih. olm.
f-'truir-jcr and L ilfuse Light. 'Alt. 20m.
Waked at 3"1 15"°, and foui'l tlie sky perfectly clear, and very brilliant. Git an observation. Both the Diffuse
and Stronger Light very decided. At 3'' 40'", the sky was all overclouded, and rain was pouring down. So changeful
are the skies at this time.
OBSERVATIONS ON THE ZODIACAL LIGHT.
217
218 OSSEBVATIONS OS THE ZODIACAL LIGHT,
No. 109.
JANUARY 27th, 1851: EVEXIXO.
Lat. 26- 10' X.: Lon. 1273 42' E.
Sun set 5A. 35w.
Stronger and Diffuse Light at 7 and 8 o'clock.
Have been trying lately to watch the change from twilight into the Zodiacal Light, but have been baffled by the
ever-shifting clouds. This evening the red light on the horizon, after su iset, changed gradually into a dull grey,
evenly diffused : at G1' '25m, this grey began to brighten up a little; and inure so below Venus than in any other place:
at 6h 30"' it was bright, but still not Zodiacal — ('. c., it was not confined to the Zodiacal Light bounds. Then clouds
gathered over, and I could do nothing more till Ym; at which lime, and at, 8'', got boundaries as in chart. Then
clouds again, which continued all the rest of the night. At 71' the sky was remarkably bright and clear ; and I
noticed, what had struck me also for two or three nights before, that the Stronger Light tapered off gradually above ;
thus running into a sharp cone. At 8', that part of the sky was obscured by clouds, and I could not see whether
the Zodiacal Light yet continued or not.
OliSERVATIONS ON THE Z<M>l AT.U, U01TT.
219
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220 OBSERVATIONS ON TIIE ZODIACAL LIGHT,
No. 110.
JANUARY 30th, 1854 (Monday) : MOESIKO.
Lett. 2C= 10' N.; Lon. 127° 42' E.
Sun rose 6A.
f 2A. Om.
Stronger and Diffuse Light -j Paled sky l/i. 30m, and 4A. Om.
U ° j
Clouds from the 27th till List evening. Kose at midnight, but tlic sky was cloudy. Was called at lh 15m, and found
the skv clear, except a cloud at the east, which was sinking towards tin- horizon, (I11 15'" no Light in the wesf.) When
it had Mink sntlicienily at 2\ got observation ; also at o'1, 4'1, and 51'. 8ky very clear, and good Cor observing. Tl it-re
was a paled sky beyond the Diffuse, of which I have given outlines at 1" oO"' and 4h. Am not quite certain that this
•went Uj> as high as the Milky Way, hut thought it did. There is a broad streak of sky from Eegulus up to the Milky
Way, within the dotted lines, which puzzles me. I cannot make out whether its peculiar appearance is owing to the
Zodiacal Light, or to a want of stars and a steady paleness or dimness there.* From Prresepe up, however, it seems
to amount almost or quite to a positive light, like the Diffuse Zodiacal Light. At 3h, 4'', and 5'1, however, I could
not sec it higher than nearly to Regulus. But these palenessvs are all so indefinite, that it is often difficult to get
their boundaries ; and at 2'' it was difficult to get the limits of the Diffuse Light, within the paled sky. At 2h got
the Stronger Light, but it was dim.
It is worth noticing how, as the hours pass, and the ecliptic becomes rapidly more and more inclined to the horizon,
the Zodiacal Light, both Diffuse and Stronger, but more especially the bitter, slides over towards the left, or north.
At 51', the Milky Way was some distance above the horizon, and tin- Stronger Light was very evidently crossing it,
and making itself as inaiked in its boundaries as if there were no Milky Way there.
At 5" 20"' dawn.
0 P. y. — See entry of February 15th, instant.
•
222 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 111.
JANUARY 30th, 1654: EVENING.
Lat. 26° 10' N.: Lon. 127° 42' E.
Sun set 5/i. 38im.
Stronger Light ~h. 50m, &c.: Diffuse, TA. 50m,
Sun's Ion. 311° 20'.
There can be no doubt that iJiere are pulsations in the Zodiacal Light. I noticed them last evening (the sky being
very clear); but, it being Sunday, made no particular record of them. They were, however, distinctly to be seen;
and when I called the attention of one of the quartermasters to them, he very easily made them out. His language
about the Light was : " Now it seems to be dying away ;" " now it is brightening again," &c. All this applied,
however, only to the Stronger Light: it occurred between 7h 30'" and 8 o'clock. This evening I was on the careful
lookout for them, and, with watch in hand, made record of the changes and their times. Clouds interfered till 7h 50'",
when, this part of the sky having cleared up, I got observations. The pulsations were very distinct; observable,
however, only in the Stronger Light. This, at 7h 50% had its boundaries as in the line b (see chart), and was very
bright : at 7'1 52'" it had suuk to the boundaries marked a, and was very dim : 71' 54'" had risen to b again, and was
bright : 7" 55'" at a, and very dim : 7" 56 at b, and bright : 7" 57 at a, and very dim : 7'1 SS-^"1 at b, and bright : 7" 5'J^'"
still at b, and bright : it seemed now to be permanent at b; but clouds soon after spread over the sky, and shut out
everything from sight.
These pulsations, in order to be seen, seem to require that the ecliptic should be at a high angle with the horizon ;
at which time the Stronger Light is very brilliant. Last evening about 7h 20m or 30'n, I overheard one of the quar-
termasters, as he was Junking at it, remark to another : " If that was not in the wrong part of the sky, I should say
that the sun was just going to rise there."
OBSERVATIONS ON THE ZODIACAL LIGHT.
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224 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 112.
.lANT'AKY 31st. ls;>l : MonxiNO.
L;it. 2U- in N. : Lon. 127 12' E.
Sun n>sc 6J. 4H;n.
f iv1 I'"" 1 f .-!.',. 15m.]
Stronger and Diffuse Light -J f ,.' }-' -J4 lo U'.iK-dsky.
i ii
15 0 J I5 J
Sun's Lon. 31 17 21'.
There were clouds intervening till 2'1 151" ; after winch got observations a-i in the chart. At, 2h lo"1 the Stronger
Liglit was dim, hut gave reliahle h mn laries. It is difficult to make out exactly the 1> mnd-i of the Diffuse Light, on
the le't, on a'XMiiut of the pale'l sky Imyiui 1 it on that side. The Strongi-r Light is now very dim. c>in;>irel with
what it was some tim:.1 ago. No pulsations seen, though I watched attentively. At .">'', clouds on t.'ie right pre-
venled my getting boundaries of the Diffuse Light. The limits of the pale 1 sky are given in the, c-'iart, in dotted lines.
OBSERVATIONS ON THE ZODIACAL LIGHT.
225
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226 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 113.
JANUARY 31st, 1854: EVENING.
Lat.'SG0 30' N. : Lon. 127° 45' E.
Sun set 5A. 3^m.
Stronger Light'f-A. &c. : Diffuse Sh. and 9A.
I was, at this time, on an exploratory tour over Loo Choo, but still made out to get good observations, and was
particularly watchful about the p ilsations of the Light. Moon set about 8 o'clock. For limits at 8h and 9h, see chart.
The pulsations appeared, and were as follows : At 8h 3m, the Stronger Light was at a, and dim ; at 8'' 5m, at b, and
bright ; at 8" Sm, at a, and dim ; 8" 12m, at b, and bright ; 8" 15™, at a, and dim ; 8" 19'°, at b, and bright ; and con-
tinued as at 81' 19m till 8h 22m, when it began to ascend towards c, which it reached by 8h 25'", and where it remained
permanently. At 9" it had this last (f) boundary, but had become considerably dimmed.
OBSERVATIONS ON THE ZODIACAL LIGHT.
227
29
228 OBSERVATIONS ON THE ZODJACAL LIGHT.
No. 114.
FEBRUARY 1st, 1854 : MORHINO.
Lat. 26° 30' N. : Lon. 127° 45' E.
Sun rose 6A. 49m.
Stronger and Diffuse Light at 2, 3, and 5 o'clock.
Sun's Lon. 312° 22'.
The sky this morning was very good for observations ; had one at 2 o'clock, at which time the Stronger Light,
though dim, still gave reliable boundaries. At 3", it was brighter, though still dim, for it ; at 5", also dim, compar-
atively. It had then slid considerably over to the left.
OBSERVATIONS ON TI1K ZODIACAL LIGHT.
' , ' .' ' . ;;
230 OBSERVATIONS ON THE ZODIACAL LIGHT,
So. us,
»
FEBRUARY 2d, 1854: M
Lat. 26° 45' N. : Lon. 127= 45' E.
Sun rose CA. 50m.
Stronger and Diffuse Light at 3A. 30m. and 4/i. 30OT.
Sun's Lon. 313° 23'.
Clouds last evening, and also this morning till 3" 30"', when, and at 4" 30m, 1 got observations. The sky was
bright, but the Stronger Light, at 3h 30m, was very dim., for it.
OBSERVATIONS ON THE ZODIACAL LIGHT.
231
232 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 116.
FEBRUARY 4th, 1854; MORNING.
Lat. 20° 33' N. : Lon. 127° 54' E.
Sun rose 6/(. 47m.
Stronger and Diffuse Light at 5 o'clock.
Clouds since last entry (2d) until 5" tins morning, when I got a good observation; for which see chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
233
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234 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. IIT.
FEBRUARY 15th, 1854: EVENING.
Lat. 35° 19' N. : Lnn. 139° 43' E.
Sun set 5/i. 33m.
Stronger Light j ^'" j'1"1' I Diffuse 7fc.
This was a very fine evening ; sky remarkably clear and good, except a sUeak of whiteness along the horizon,
which, however, did not interfere materially with the Zodiacal Light. I watched for the first appearance of this
Light. At G'1 30mj the western sky. above, was one uniform color ; G'1 45'", the Zodiacal Light became dimly
apparent — rather suddenly so — but no clearly definite bounds ; G1' 4*7'", quite decided up to the Pleiades ; could have
got bounds, but preferred waiting till they should be more decidedly marked ; Gh 50"', Stronger Light now showing
itself, but no reliable boundaries to it ; at 7h, and at 7" 10"', got boundaries. At this time the Stronger Light was
bright ; had some suspicions of pulsations from a to b (see chart), but was not certain ; could not watch with that
care that such delicate observations require, as I was anxious to catch the first appearance of the moon's Zodiacal
Light, now expected soon to appear ; so I turned from the western to the eastern horizon.
Observation. — " There is a regular paleness of the sky from Eegulus, up by Prrcsepe, &c., to the Milky Way, and
about 8° wide ; its centre nearly or quite on the ecliptic. It amounts almost, if not quite, to a positive light, and
seems like a dim branch of the Milky Way, that has strayed off from the general course." — My Nofc*.
OBSERVATIONS ON THE ZODIACAL LIGHT.
235
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230
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 113.
FEBRUARY 17ih, 1834:
Lat. 35^ 19' N : L..II. I39=>43'E.
Suu set 5/i. 4U/».
!7A. OCT.
' 30'
9 0
Clouds and rain last evening. The early part of this evening was perfectly clear, and very fine for observations.
Took boundaries at 7", and then watched to see whether there would be pulsations. Saw them, but they were not as
distinct as at the last observations of this kind ; yet, with close watching, they could be easily made out. They were
confined to the Stronger Light, which, at 7 o'clock, was at d.
li. m.
At 7 3, at c.
7 7, at d.
7 10, at 6.
7 12, at d.
7 14, at a, and very dim.
7 15, at IT, and almost extinct.
7 17, at b, and brighter.
7 18J, has just reached c.
7 20, has just readied d.
7 21, has just reached b.
7 22-A, still at 6.
h. m.
At 7 24, at c.
7 25, at d.
7 2G, has got up to e, but not brighter than when
at d.
7 30, has got up to/.
7 35, still at /.
7 3'J, there seems to be a pulsating between d and/,
and perhaps has been since 71' 31"', but I cannot
speak with certainty.
7 44, same as at 7 ' 3'J1".
8 0, clearly no pulsations evident to the senses.
At S11 and 9'', the northern boundary of the Diffuse Light was difficult to be made out ; it has now become so much
more dim than formerly. I sometimes doubted whether I ought to put these b mndaries down, they were so indefi-
nite ; but I have given them as, after careful consideration, they seemed to me to be.
OBSERVATIONS ON THE ZODIACAL LIGHT.
237
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238
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 119.
FEBRUARY 18th, 1854 : EYESINO.
Lat. 35° 19' N. : LCD. 139° 43' E.
Sun set 5/i. 41m.
C 7h. Om.
Stronger Light 7/j.. &c., to 9 o'clock : Diffuse < 8 0
I 9 0
This was a beautiful evening ; sky perfectly clear. Watched to see the Zodiacal Light make its first appearance.
Sun set at 5" 40m ; sky had nothing unusual till, at 6" 50™, I became, all at once, conscioiis that I was looking at the
Zodiacal Light ; but it was dim. Its boundaries then seemed to be as in m on the chart (probably an error
occasioned by the usual horizontal whiteness) ; but the light was so dim that I could not fully rely on them. At
6" 56"' it was quite decided. At 7" the Stronger Light was at d. My attention was then called off for a few minutes,
but. at 7" 6m, it was at d, and so to 7" 10'" ; all this while very bright. At 7" II"1 it was dim ; but at 7" 12m it had
brightened again and dimmed, and it was now at a.
h. m.
At 7 13i
7 14,
7 15,
7
19,
20,
22,
23,
25,
26,
7
7
7
7
7
7
7 28,
7 29,
7 30,
7 31,
7 o2u
7 34,
7 38,
, still at a.
at c, and bright.
at b, and dim.
still as at last.
at a, and as if dying away.
still as at last.
at c.
still as at last.
at d, and very bright.
, still as at last.
at b, and dim.
still at b, and as if dying away.
same.
at d, and very bright.
, still the same.
at e.
still at e, but not so bright as when at d. It
seems to be pulsating still, but I canuot tell
with certainty.
h. m.
At 7 40,
7 42,
7 43, ate, brightened.
7 44, at e. It is dim for this altitude.
7 45,
the brightness pulsates, but I cannot perceive
any pulsations in the boundaries.
at e. The light is dim for this altitude.
do. do. do.
7 48, still the same.
7 49, at e. Some little brightening up.
7 51, at e, has brightened so as to be as when for-
merly at d; so it remained.
8 0, it was at f, and there were no more apparent
pulsations.
9 0, light steady. It has gradually dimmed since
8'1, but is still tolerably bright.
10 23, boundaries as at 9h, and light faint.
OBSERVATIONS ON THE 'ZODIACAL LIGHT.
239
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OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 120.
FEBRUARY
li, l-:,t: EVEMNG.
Lat. 35° l!i' X. : L.m. 13?,° 43' E.
Sun Ret &/( 42 vi.
( 7/i. liw i
Stronger Light < 7 10 > DilFuse at T/i.
(7 16 )
Some clouds along the western horizon ; but, at Y\ ^nt li inn 1 ivies ns in the chart ; the boundaries, however, not
very distinct. Began soon a'U-r to oli.-L'rve pulsations ; but as tliese rt';|iiire a ^nn,l sky in order ti) be taken reliably,
and the clouds broke the view, I soon <jave u;> the efForf. It, w:n evident, however, that the pulsations were goinsj
on, both in the extent and in the brightness of the Z idi.icil Srroii^rr Li^lit. At 7'1 10" and 7!l 1R'", the Light was
as in the chart. At 71' If!'" it had just lirighirnrd an 1 risen ; luit I cmil 1 get nothing reliable below. At 8^ the
clouds had covered all the sky ; and so they remained during the rest of the night.
OBSERVATIONS ON THE ZODIACAL LIGHT.
241
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OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 121.
FEBRUARY 21st, 185<t: EVENING.
Lat. 35° 19' N. : Lnn. 139° 43' E.
Sun set 5/i. 43£>n.
Stronger Light 7/i. 15m., &c., to 8A. : Diffuse 7A. 30m.
Clouds and rain all day, and a gale blowing. Did not look for any thing in the evening ; but all at once I found
the stars out, and the sky perfectly clear. At 7'' 15m I was ready to make a record of the sky. At that time the
Stronger Light was at a.
h. m.
At 7 36, at b.
7 37, at d.
7 38, do.
7 40, at e.
7 41, do.
43,
44,
46,
47,
do. but dim.
do. and bright,
do.
do. ami dim.
h. m.
At 7 19, it was at c.
7 20, at b, and dying away.
7 21, at a,
7 22, do.*
7 23, at b.
7 25, at d.
7 26, do.
7 27, at a.
7 28, at d.
7 30, do. and has brightened till it is as if the sun
was just going to rise.
7 31, at b.
7 32, do.
7 33, at d.
7 34, do.
7 35, at a, and seems to be dying away.
It was uniformly dim at the lower elevations, and bright at the higher ; but the Light seemed generally to rise
faster than it brightened.
Clouds crossed the sky soon after 8h, and at 9h I could get no observation.
7 48, at/, and bright.
7 51, do. and bright.
It seems to be permanent at
/, and is quite bright ; but not so bright at
its lower part as when it was at d.
7 54, still as at 71' 51m.
8 0, it has risen to g, but no longer pulsates.
* In all this record of pulsations, " do." means still continued as at the last.
OBSERVATIONS ON TUB ZODIACAL LIGHT.
243
1
31
244
OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 122.
FEBRUARY 23<I, 1854: EVENING.
Lat. 35° 19' N. : Lon. 139° 43' E.
Sun set 5A. 4.r>£m.
Stronger Light, 7A. 8m., &c. > «.,,. „, ,n , 0, on
to 8 30 > Diffuse, ,k. 10m. and 8A. 30rn.
Cloiids last evening. This evening blowing a gale, (thermometer 37°, and at 3 a. m. at 32° Fahrenheit.) but the
sky beautifully clear, and very fine for observations. Had the pulsations of which I took account, as follows. The
was at c : 7h 12'" still the same, and now bright :
h. m.
At 7 34, at c, and very bright.
7 344., dimming, and descending.
7 35* at 6.
7 354, at a, and dying away.
,
3T,
38,
at c, and tolerably bright.
do. do.
7 384,, at c, and very bright.
40,
41,
7 42,
do.
do.
do.
do.
and not so bright,
do.
42J,
44,
do. and tolerably bright.
do.
do.
Stronger Light at 7" 8
h. m.
At 7 13, at b, and dim.
7 14, do. and very dim.
7 15, at c, and bright.
7 16, do. do.
7 164., do. and strikingly bright. *
7 174, do. do. do.
7 184,, at b, and dim.
7 19, do. do.
7 20, at c, and bright.
7 224, do. do.
7 234., at a, and dying away.
7 25, brightening and rising.
7 26, at c, and bright.
7 264., do. and very bright.
7 27, do. do.
7 274., begins to be dimmed, and to descend.
7 28£, at 6.
7 294., at a, and dying away.
7 30, at b.
7 31 J, at c, and bright.
7 324., do. do.
7 33, do. and very bright.
The Diffuse Light is very dim, and can scarcely be bounded reliably ; but I give it as it appears to me.
I notice, as a general thing, that the Light, when it ascends, gets its full elevation a minute or so before it gets
its full brightness.
Very severe work this evening. The gale, with sharp air from the snowy mountains west of us (Bay of Yedo,
Japan), seemed to pierce through the whole system; and when the work was through, I found it impossible to get
warm. Had an attack of pleurisy in consequence.
7 444, at d, and quite bright.
7 46, do. do.
7 474., do. and not bright.
7 49, do. and bright.
7 50 ; it seems to be permanent at d : there seem to
be some pulsations in brightness ; but it is
difficult to make them out reliably.
8 30, permanent at the place marked in chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
245
246 OBSERVATIONS ON THE ZODIACAL LIGHT
No. 123.
FEBRUARY 24th, 1S54 : EVENING.
Lat. 35° 25' N. : Lon. 13J° 41' E.
Sun set 5A. 46m.
Stronger and Dittuse Light, 7/i. 43m. and 9/r.
Clouds till Yh 45m, when I got an observation : some clouds below prevented observations for pulsations. At 9h the
Stronger Light had faded considerably ; clouds after that. (On the morning of the 24th, I went on deck at 3 o'clock,
but although I could see that there was a Zodiacal Light, I could not get its boundaries ; it was so faint, and its
limits so indistinct. The ecliptic is now, in this latitude, very much inclined to the horizon. Was on deck also at
4h, but with a similar result ; saw the Light, which was stronger than at 3", but with no reliable boundaries. The
difficulty is increased by the fact that the widest part ot the Milky Way now crosses the Light just above the horizon.
At 5" went to try it again, but the moon was up ; so did not succeed.)
OBSERVATIONS ON THE ZODIACAL LIGHT.
247
»
3.1
248
OBSERVATIONS ON TUB ZODIACAL LIGHT.
No. 124.
FEBRUARY 25th, 1854: EVENING.
Lat, 35° 25' N.: Lon. I39U 41' E.
Sun set 5/i. 47,1 m
Stronger Light 7/(. 14m., &c., to 10/i. 3Um.: Diffuse -j g "(
Sun's longitude 336° 36'.
f 7/t ]5m.
8 (1
9 (I
10 0
Clouds this morning.
At 7 35, dimming.
7 35-J-, at c.
7 36, at b, and dim.
The evening sky was perfectly clear and very favorable, anil I had good observations. At
7 o'clock the Zodiacal Light was visible, but uot distinct enough for g.>od outlines ; 7'1 14m, took outlines as at d.
(There seemed to be some slight pulsations from this to 71' 19'", but could not make them out reliably.)
h. m. li. m.
At 7 19, dimming.
7 20, at c.
7 22, at d.
7 23, do.
7 24, at c.
7 25, at a.
7 2(:i, ascending and brightening.
7 2Gi, at c.
7 27, at d.
7 2R|, at a, dying away.
7 30, at <?.
7 30i, do. and brighter.
7 3H, same as last.
7 32|-, do. and very bright.
7 33, and 7" 34m, same as last.
39,
37, do.
37A, brightening.
38, at d.
do. and brighter.
do. and quite bright.
do. and not so bright.
do. and brightened again.
7 41|, do. quite bright.
7 47, has continued so, and seems now to be perma-
nent.
7 50, pulsations are now clearly over.
40,
41,
When ascending, the Light always gained its highest altitude before getting its greatest brightness at that altitude.
When this Stronger Light is going to be permanent, the lr!</fifcr portion of it (before, below the spot marked a)
now shoots up higher, as far as to b; 71' 54m, has got up to c ; 'J1' and 10", was as in the chart. At 9'' 30'", the Stronger
Light had dimmed some, but was still bright ; at 10'', boundaries as at 9" 30'" : Light dim, but easily made out ; 10"
30°', same as last ; 10'' 30m, it is sinking du\vn under the horizon — not dying away. At this hour its upper limit was
near some haze on the horizon, and I gave up observing.
OBSERVATIONS ON THE ZODIACAL LIGHT.
249
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250 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 125.
MARCH 6th, 1854: 7A. 30m., p. ui.
Lat. 35° 26' N. : Lon. 139° 42' E.
Sun set 5h. 54^m.
Joint Moon and Sun Zodiacal. — Clouds uniformly since last entry (February 25th). The moon quartered to-day,
and I was not expecting anything this evening ; but, on going on deck, at half-past 7, and looking up, I was astonished
to see the Zodiacal Light fully displayed. It was, no doubt, a joint sun and moon Zodiacal Light, the moon happen-
ing, just at that time, to be in a position in which, instead of preventing the sun's Zodiacal Light from being seen by
its own effulgence, it made an additional light, which was sufficient to show itself, even amid the strong general moon-
light. Though this Zodiacal Light was quite distinct, yet, to add to my certainty, I called two of the quarter-
masters, separately, and asked them if they saw any peculiar light in the western quarter of the sky. They (each)
saw it at once; and, on my asking them to give its boundaries, the first bounded it as in the chart, which agreed
with niy own judgment. The other gave it a wider space, but said that its brighter part was, as I have described,
within the limits which I have given it. My own mind was perfectly satisfied that it was clearly a Zodiacal Light.
It differed from, the ordinary sun or moon Zodiacal Light, in not being brightest at its lowest end, but was, all the
way down, of a pretty uniform brightness. It was quite distinct. The upper end was lost in the moon's superior
light. The night was then very clear. When I came up again, at 8" 30'", the sky was rather hazy, and nothing
of this could be made out.
OBSERVATIONS ON THE ZODIACAL LIC.IIT.
251
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252 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 126.
MARCH 7th, 1854: MORJHNO.
Lat. 35° 26' N. : Lon. 139° 42' E.
Sun rose (>/i. 25Am.
Stronger Light at 5 o'clock.
Clouds have prevented all morning observations since the unsuccessful effort of February 24th ; hut this morning
was a very clear one, and I made another attempt at 5 o'clock. The ecliptic now, in this high latitude, makes a
low angle with the horizon ; and, above the Milky Way, there was decidedly no Zodiacal Light to be seen ; but,
below the Milky Way, it was very strong, and there could be no doubt about it. I have given its boundaries in the
chart, its upper end being lost in the Milky Way. What I saw was the Stronger Light. Tbis Light was so strong
as evidently to cheat the officer of the deck in the flag-ship (Powhatan), and to make him believe it was dawn long
be ore it was really so. Some time alter G'1 the Light began to show a stronger spot towards the left, which, ascend-
ing there, soon became dawn.
OBSERVATIONS ON THE ZODIACAL LIGHT.
253
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254 OBSERVATIONS ON THE ZODIACAL LIGHT.
Ko. 127.
MiRCH 13th, 1854:
Lat. 35° 2f N. : Lon. 139° 42' E.
Sun set tih. 5m.
Stronger and Ditt'use Light at 7/i. 4Hm. and 9/i.
Clouds since tlie last date till tliis evening ; then clouds, also, till 7'' 40"', when, and at S'1, I got observations as in
the chtirt ; thought there were pulsations at 71' 40'", &c., hut some remains of clouds towards the horizon made this
not certain. The Stronger Light was unite distinct till the moon rose, at 9'1 57m.
OBSERVATIONS ON THE ZODIACAL LIGHT.
255
256
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 128.
MARCH 20th, 1854: EVENING. — (Monday.)
Lat. 35° 20' N. : Lon. 139° 42' E.
Sun set OA l^m.
Stronger Light ~h. 30m., &c., to 94. : Diffuse 74. 30m. to 94.
This was a fine evening for observations, and I was very watchful to see whether there would be pulsations or not.
Sun set at G" 74, m. At 7" 14m, the Zodiacal Light was visible, but gave no perfectly reliable boundaries,
got them both tor Diffuse and Stronger Light ; the latter was then at b.
At 7" 30"'
It. in.
At 7 :>:-;A, at b, and bright.
7 354, at a, and dim.
7 3fiJ-, at b, and bright.
7 384, still do.
7 l-i'J, at a, and dim.
7 4(H, do. do.
7 414, at b, and bright.
7 44, do. do.
7 46, at a, and dim.
7 47: dim.
A. 771.
At 7 48 J, at 6, and bright.
7 50, do. and ignite bright.
7 52, at c, do. do.
7 554, do. and very blight — brighter than at any
time before, this evening.
8 0, as at last, and seems to be permanent.
8 24, to b, and seems to be pulsating; but this is
very uncertain.
8 8, seems to be permanent.
8 12, same as last.
7 474., brightening.
At 9 [10?] o'clock, could see the Light very well to the Pleiades, but could not get its boundaries beyond that,
reli ibly. These pulsations are not as striking as a month ago, and sometimes are difficult to be made out. The
Stronger Light not so strong as formerly.
OBSERVATIONS ON THE ZODIACAL LIGHT.
257
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258
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 129.
MARCH 25th, 1854: EVENING.
Lat. 35° 26' N. : Lon. 13i)° 42' E.
Sun set 6A. I Im.
Stronger Light 7A. 30m., &c., to 9/i 30m: Diffuse 7/i. 45m.
Clouds since last, till this evening, which was very clear. Watched for the first appearance of the Zodiacal Light.
Sun sets at 6" llm At 7'1 10"' no sign of Zodiacal Light yet ; Milky Way also not yet distinguishable : 7" 25m, now,
for the first time, the Light decidedly showing itself, as also the Milky Way ; does not yet give reliable boundaries.
7" 24"', could now get boundaries at the lower, but not at the upper end ; 7" 30'", got boundaries of Stronger Light,
and at 7' 4.V1 of the Diffuse. At 7'' 35'" Stronger Light was at b, and bright ; its uppar end seemed to extend into
the Milky Way ; but ot this I could not be certain.
h. m.
At 7 50i, at b, and very bright.
^ 0, the upper end of the Stronger Light now clearly
exten Is into the Milky Way ; perhaps a little
beyond it.
8 5, Stronger Light now brighter than at any time
previously this evening.
8 22, still very bright. After this, it seemed to dim
a little.
40i,
*
(. m.
At 7 37, still at I, and bright.
7 39, at a, and dim.
7 40, do. aud quite dim.
brightening.
* (Changes apparently, but could not be cer-
tain of them.)
7 43i, at a, and now dim.
7 46, at b, and bright.
7 47i, do. do.
Sometimes these changes seemed to be very evident, sometimes so dubious that I felt reluctant to record them.
I give the notes, however, as they were made at the time.
At 9'1 30™, the Stronger Light was evidently above the Milky Way ; its outlines are in the chart, marked c c.
At 10h 20™ the Stronger Light still visible, but so indefinite that I cannot bound it.
OBSERVATIONS ON TIM: ZODIACAL i.n.'UT.
259
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280 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 130.
MARCH 27th, 1654 :
Lat. 35' 26' K. : Lon. 13S° 42' E.
Sun rose 5h. 53%m.
I 4A. 22m. )
Stronger Light/ 4 30 > Diffuse 4A. 2'2m , 4A. 43m.
( 4 40 )
Zenith Point at 4A. 45m. ; Lat. 58° 20 N. : LOD. 248° 0'.
(26th was Sunday.) WHS called at 4 o'clock, and had an extremely interesting observation. The peculiar
interest arose from the fact of the obliquity of the ecliptic with the horizon. (The angle was 31° 9'.) Yet the
Zodiacal Light, which was perfectly distinct, went stretching along the ecliptic, so that a line along its central part
•would make an angle of about 77° with a line perpendicular to the horizon. The boundaries are given in the
chart. It will be seen that the right-hand or southern boundary of both Diffuse and Stronger Light shifted to the
right as morning advanced and the horizon receded from it. Dawn at 4" 39™.
OBSERVATIONS ON THE ZODIACAL LIGHT.
261
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262
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 131.
MARCH 27tli, IS54: EVENING.
Liit. 3J° 2(3' N. : Ltm. 139° 42' E.
Sun set Git 12.W».
Stronger Light j g''1 g,'™' j Diffuse at 7/i. 30m., &c.
Sky remarkably clear. The following are my notes : — V 15°', a whiteness running up with the Zodiacal Light
boundaries as far as the Pleiades, but its limits are not distinct : 7" 24'", the light more decided, but its boundaries
not reliable: 7" 30'", got boundaries of both Diffuse and Stronger Light — the latter, then, strong up to b, and,
gradually tapering, dimming off to c.
h. m.
At 7 35, at a, and dim.
7 38, do. do.
7 39, at b, and bright.
7 43, do. do.
7 44, at «, and certainly dimmed.
7 45, at b, and bright.
7 47, at a, and dim.
7 484, do. do.
7 49, brightening.
7 50, at b, and bright.
7 51, at b, and quite bright.
7 52|-, dimming.
7 524, at n, and dim.
7 534, brightening.
At 7 54^, at 5, and bright.
7 .">.">•?,, at b, and quite bright.
7 57^, at a, and quite dim, as if dying away.
7 58|- do. do. do.
7 58|, brightening.
7 59-J, at b, and bright.
0, do. and quite bright.
3, brighter than at any time yet, and has clearly
ascended to the Milky Way by lines d d.
4-J, dimmed, and sunk to l>.
7, brightening.
8, very bright, and at d d.
8 15, still as at last, and seems to be permanent now.
9 30, boundaries to x.
8
8
8
8
8
I think I can know when it is going to be permanent, by the upper portion of the Light brightening more than at
anytime previously in the evening, and the strong brightness ascending higher up. The first appearance of the
Zodiacal Light seems to be a white light — i. c., when the twilight is not fully gone ; afterwards it changes to a warm
yellowish light. The reverse of this happens in the morning. The Diffuse Light is now very dim : in the morning
it is very strong, for it.
This evening was remarkably fine for observations, and in my notes is the remark: " It certainly does pulsate."
OBSERVATIONS ON THE ZODIACAL LIGHT.
263
.
L.
264 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 132.
MARCH 28th, 1854 : MORNING.
Lat. 35° 26' N. : Lnn. 130° 42' E.
Sun rose 54. 5^m.
Stronger and Diffuse Li^ht at 4h. and 4/j. 3f)m.
Zeuith at 4/i. 311m., Lat. 57° N.: Lon. 245°.
Was on deck at 4 o'clock. Previous to that, the Milky Way is too near the horizon for any valuable observations.
At 4h, could not get the lower or southern boundary of the Diffuse Light, on account of its propinquity to the horizon.
The morning was unusually clear-, but could see no Zodiacal Light above the Milky Way. The Diffuse Light,
especially on the left, or north, is now so strong that it is rather difficult to say where the boundary-line between it
and the Stronger is. Dawn about 4h 43'°.
OBSERVATIONS ON THE ZODIACAL LIGHT.
265
266 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 133.
"i . I.VIi -2Stii, 1851;
Lat. 35 -' 2(/ N. : Lnn. 139- 42 E.
.Stni set 6/t. 13m.
rnd
Clouds in tlie early part of the evening. At 10 o'clock, was able to get nn observation. The- /i>.ii;u-;i.l Liglit dim,
but perfectly distinct: the course of tlic Strong! r Lii.';!^. ri.nli! i.r v.^uliu- traced across Hie ^!ill^y Way.
OBSERVATIONS ON THE ZODIACAL LIGHT.
207
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268 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 134.
MARCH 29th, 1854: MORNING.
Lat. 35° 2G' N. : Lon. 139° 42' E.
Sun rose 5/». 5.c>£m.
Stronger Light at 4A. and 4A. 31 'm. : Diffuse 4A. and 4A. 24w».
Zenith point at 4A. 3('m.: Lat. 5b° N. : Lon 246°.
Was on deck at 4 o'clock, and got boundaries for Diffuse and Stronger Light, except the lower edge of the former,
which was not decided enough till at 41' 24"'. A haze along the horizon prevented my observing any changes in the
lower boundaries as the horizon sunk ; there were none in the upper. Dawn at 4h 40m.
OBSERVATIONS ON THE ZODIACAL LIGHT.
209
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270
OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 135.
MARCH 29th, 1854 : EVEITIKO.
•
Lat. 35° 26' N. : Lon. 133° 42' E.
Sun set Gli, 14m.
Stronger Light 7A. 28m., &c., to JOA. : Diffuse 7A. 40m. and 9A.
A very favorable sky for observations. Sun set at 6h 14m. At 7h 14m a whitish light all along the horizon, but
inns higher up towards the Pleiades than at any other part ; 7h 24m, there is now evidently a brightness running up
beyond the Pleiades, but it is not strongly eneSigh marked to give certain boundaries. At 7" 28m it is quite distinct,
and I get boundaries, as at a.
li. in.
At 7 31, it is at 5.
7 32, do. brightening,
7 35, at c, and bright.
7 36, at b, and dimmed.
* * * *
7 40, at c, and bright.
7 43, at I, and now evidently dimmed,
7 44, do. do. do.
7 44i, brightening.
7 45, at c, and bright.
7 46^, at b, and dim.
7 48, at c, and bright.
7 491, do. do.
7 51, at d, and extremely bright,
7 52J, at b, and very dim.
7 53^, brigbtening.
7 54^, at d, and very bright.
7 57£, do. still bright.
A. TO.
At 7 58, dimming.
7 58j, at b, and dim.
7 59|, do. brightening,
8 0, do. bright.
8 I, at d, and bright.
8 2, do. do.
8 3, at b, and dim.
8 3|, at 6, and brightening.
8 4^, at d, and bright.
8 6, at d, very bright.
8 12, do. still very bright, and seems to be perma-
nent in height.
8 13, there seem to be some slight pulsations in in-
tensity, but I cannot catch them reliably—
cannot be certain about them.
10 0, found the Stronger Light up to above Castor
and Pollux, and already making its course
across the Milky Way.
OBSERVATIONS ON THE ZODIACAL LIGHT.
271
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OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 136.
MARCH 30th, 1854: EVENING.
Lat. 35° 26' N. : Lon. 139° 42' E.
Sim set 6li. ]4»». 4ds.
Stronger Light 7A. 37m., &e., to lU/i.: Difluso 7/i. 43m. and 9A,
The morning cloudy. At 7" 3CP tins evening, there was a ginunl whiteness within the boundaries a a ; at 7" 37"',
boundaries at c.
h. m,
At 7 43,
7 44,
7 44$
at 6, and dim.
do. do.
, brightening.
7 45, at c, and bright.
7 47, do. do.
7 49, at b, dim.
7 50, brightening.
7 50|, at c, and bright.
7 51, do. do.
* * * * Not reliable.
7 54, at 6, and dim.
7 54J, brightening.
7 55^, at c, and bright.
7 5G|-, at d, and bright.
7 57|, at d, and very bright.
7 59, dimmed.
8 0^, at d, and very bright.
8 2, extremely bright.
8 6, still as at last.
h. m.
At 8 Gj, suddenly dimmed ; is at b, and dimness, as if
the light were dying away.
8 9, do. do. do.
8 9-J, brightening.
8 10 j, at d, and bright ; but not as bright as at S1'
2'", &c.
8 12, at d, and bright as at 8'' 6'".
8 13^, at «, and dim.
8 15, brightening.
8 15^, dimmed.
8 16-J-, dimmed.
8 17, brightening. Tlie.se last pulsations were not
very distinct. I have recorded what seemed
tn me to be the case.
8 23, seems to lx- permanent at d, but is considerably
dimmed from what it was at 8'1 6'°.
9 20, Stronger Light clearly above Milky Way, and
marking its course across it.
10 0, still (|uite distinct.
OBSERVATIONS ON THE ZODIACAL LIGHT.
273
2*74 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 1ST.
APRIL 1st, 1854: MORSINO.
Lat. 35° 26' N.: Lon. 139° 43' E.
Snu rose 5h. 51m.
Stronger and Diffuse Light at 4A. and 4h. 30m.
Zenith poiut at 4/i. 3 im.: Lat. 58° 3D' N. : Lon. 250° 30'.
Clouds since last. This, a fine clear morning, excellent for observations. Got boundaries at 4h and 4b 30m : it is
difficult, however, at 4'1 30m, to ascertain the dividing line between the Stronger and the Diffuse Light on the left
hand ; the Diffuse Light itself being strong. Have given them as they appeared to tne to be. At 4h 30m, I thought
I saw an increase of light shoot suddenly along within the boundaries of the Stronger, and that this increased light
remained, but would not be certain of it. At 4" 41m, decidedly dawn. Have drawn the boundary of the Diffuse
Light across the Milky Way, near the horizon; it being strong enough to make itself evident there.
OBSERVATIONS ON THE ZODIACAL LIGHT.
275
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276 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 138.
APRIL 17th, 1854 : EVENIKO.
Lat. 35° 19' N. : Lon. 139° 43' E.
Sun set UA. 29i/n.
!7A 35m.
9 30
10 30
Clouds ever since last date, except one evening, and then the moon (at full) prevented observations. This evening,
the sky above was not very clear, and there was a thick haze along the horizon ; hut still I had some good obser-
vations. It' there were any pulsations, I could not see them on account of the haze. The times of observation and
results are given in the chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
277
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278 ©BSERVATIONS ON THB ZODIACAL LiaHT.
No. 139.
APRIL 18th, 1854: EVENING.
Lat. 34° 40' N. : Lon. 138° 59' E.
Sun set Gh. 30m.
Stronger and Diffuse Light, 8 and 9 o'clock.
The mornings are now very hazy, the sky covered with clouds. As the day advances, the clouds are dissipated,
and the haze becomes thinner; till, in the evening, the sky admits of observations, though not perfectly clear. This
evening, although there was a white light within the Zodiacal Light limits at aa earlier hour, I could not get
reliable boundaries till 8 o'clock. After 91', clouds interfered. In this haze, it was not easy to get the boundaries of
the Diffuse Light ; but I believe that those given in the chart may be depended on.
OBSERVATIONS ON THE ZODIACAL LIGHT.
279
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280
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 140.
APRIL 20th, 1854 : EVUNIHG.
Lat. 34° 411' N. : Lon. 133° 59' E.
Suu set (Vi. 3 1 HI.
( 7 50/n. )
Stronger Light J 9 0 > Diffuse 8A , 9A,, and IDA,
( 1" " )
Last night cloudy. This evening very clear and bright. \Wchel for the first appearance of the Zodiacal Light.
At Y;' 44"1 it showed itself; but it did not give reliable b >;iu laries till 71 ">0". The Stronger Light evidently moves over
towards the left as the ev.iuin^ alvi ices; pr >'t.ibly owing to the change in the obliquity of the ecliptic. At 10h, the
boundaries appearel to be the same as at 9'; but it was difficult then to get the bounds of the Stronger Light,
especially on the left, or south. The Diffuse Light is now very bright, particularly towards the southern side,
OBSERVATIONS ON THE ZODIACAL LIGHT.
281
Es,
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282 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 141.
APRIL 21et, 1854: EVENING.
Lat. 34° 40' N. : Lon. 138° 59' E.
Sun set 6/j. 32m.
( 7/i. b'lrn. )
Stronger Light/ 9 0 V Diffuse, Sit., 9/t., and 10/..
(10 0 )
A very clear night. At Th 40"1 there was a whitish light distinguishable, extending np to Castor and Pollux ; at
I7h 52ra I was able to get reliable boundaries, as in the chart. The sky was so remarkably favorable for observations
in every respect, that I looked out carefully for pulsations, but was not able to see any. Two or three times I
thought the Light faded a little ; but there was nothing reliable, and I concluded, finally, that there were no
pulsations. At 101" the Light was still very distinct ; the Diffuse Light grows stronger as the night advances (to a
certain point), and at 10h it is difficult to distinguish between it and the Stronger Light ; but I thought the bound-
aries of both were about the same as at 9h.
OBSERVATIONS ON THE ZODIACAL LIGHT.
283
36
284 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 142.
SUN AND MOON.
APRIL 22d, 1854: MORNING: (Monday)
Lat. 34° 40' N. : Lon. 133° 59' E.
Sun rose 5fi. 24£m.
Sun, Diffuse 2A. 45m. : Moon, Stronger 3A. 18/n. ; Diffuse 2A. 57m. and 3A. 3m.
Zenith point at 3h.: Lat. 57° 40' N:: Lon. 249°.
Was on deck at 2" 35m. Morning remarkably clear, with stars, seaward, down to the horizon ; on the east, some
hills in the way. At that early hour the Zodiacal Light was easily distinguishable, and I got the upper boundary
of the Diffuse at 2" 45m ; the lower was hidden by the hills. At 2h 50'" the Light began to brighten at its lower
side, and I saw the moon had got near enough to affect it. Took the upper boundary b of this Moon Zodiacal Light
at 21' 5*7™ ; and at 3" 3"1, c; at 31' 18"' there was a great brightening in a part within the boundary a; at 31' 24™., the
moon showed itself above the hill.
The observation was unsatisfactory, for the rnoon came so early as to prevent a good Sun Zodiacal Light, and
was not strong enough to give a good one from its own light ; but I give the result for what it is worth.
OriSKKVATIONS ON TUK ZODIACAL L1GUT.
285
IS
as
==
:
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286 OBSERVATIONS ON THE ZODIACAL LIGI1T.
No. i...
APKIL 24th, 1854 ; EVEHIS<-.
Lat. 34° 40' N. : Lon. 136° 59' E.
Sun set 6A. 36m.
Strongur and Diffuse Light at eh., 9k., and 10A.
Clouds since last date till this evening, which, also, was cloudy till S'1 ; but, from that on, very clear and bright.
For results, see chart. At 10'' the boundaries appeared to be as at 9" ; but it was difficult to get them. The Diffuse
Light had, perhaps, ascended a little ; brft I could not tell with certainty. Thought, sometimes, that the Stronger
Light pulsated on its northern side,
OBSERVATIONS ON T1IE ZODIACAL LIGHT.
287
S3
288
OBSERVATIONS ON TIIE ZODIACAL LIGHT.
No. 144.
APRIL 25th, 1854: EVENING.
Lat. 34° 40' N. : Lon. 138° 59' E.
Sun set Gli. 35m.
Stronger and Difl'use Light at 8A., 9/i., and IDA. 20m.
A fiae clear niglit.
At 7h 46m tlie Zodiacal Light was distinct up to Castor and Pollux ; could not get bound-
aries till 7'' 55"1, when the Stronger Light was at b. At 8'' 7'" it was very strong, and I began to think that this
great and rapid increase of light must Ivlong to pulsations. Watched, therefore, carefully (as the night, very
clear, was so for a favorable one), to have further proofs one way or the other. The Milky Way crossing the
Zodiacal Light was against such observations ; but I soon became pretty well satisfied that there were pulsations
in intensity, and also in the boundary on the right or northern side. My notes, taken at the time, were as follows :
h. in.
At 7 55, at b.
8 7, strong.
8 10, dimmed, and at a.
8 15, dim, do.
8 17, at c, and bright.
8 22, dvi:'nl<.'illy at c, and bright.
8 23, do. do.
8 24, dimming.
8 24J, at a, and decidedly dimmed.
8 26, do. do.
8 28, brightening.
//. m.
At 8 32, at c, and bright.
8 34, do. and very bright.
8 36, do. do.
8 37, do. dimmed.
8 42, do., seems to be still dim; but there is now so
little space between (lie Milky Way and hori-
zon, that it is difficult to judge, and I give up
observing.
10 20, the boundaries were apparently as at 9'1, but
the light was all very dim.
OBSERVATIONS ON THE ZODIACAL LHJHT.
289
290 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. U5.
APRIL 26th, 1854 : MOHKINO.
Lat. 34° 40' N. : Lon. 133° 59' E.
Sun rose 5A. 20m.
Stronger and Diffuse Light at 3/(. and 34. 40m..
Zenith point at 84. 40m. : Lat. 58^ 8' N. : Lou 271)°.
Clouds in the morning since my la-it morning date. Was on deck at 3'' this morning, and was able to get bound-
aries on the upper side of the Zodiacal Light. The Light, however, was dim ; both then, and till dawn, much
dimmer than on the first of this month, and for some time previous. The glare from Jupiter is also now trouble-
some. At 3" 40'" got boundaries on both sides, but found the Diffuse Light ill defined on its lower side. Dawn
OBSERVATIONS ON THK ZODIACAL I.KI1IT.
291
37
OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 148.
APRIL 26th, 1854 : E
Lat. 34° 40' N. : Lon. 133° 59' E.
Sun set 6A. 3Gm.
Stronger and Diffuse Light at 8 and 9 o'clock.
Evening hazy, and by no means favorable ; still, was able to get observations at 8h and 9b, which may be con-?
sidered tolerably reliable. Did not look for pulsations, as, if there were any, the sky evidently would not admit of
their being seen. At 10b there was still a Zodiacal Light, but it was dim and undefined,
OBSERVATrONS ON THE ZODIACAL LIGHT.
293
294 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 147.
APRIL 27th, 1854: MORM.V.
Lat. 34° 40' N.: Lon. 138° 59' E.
Sim rose 5A. 19,Jm.
Diffuse anil Stronger Light at 4 o'clock.
Zenith point at 4A.: Lat. 58° 25' N.: Lon. 279°.
Morning hazy, and the observations very unsatisfactory. It was not till 4 o'clock that I was able to get 'boundaries ;
and them I should scarcely have known how to draw, but from knowledge gained from observations on previous
mornings. With such guidance, I was able to trace the outlines ; but this, consequently, cannot be considered «n
independent observation ; and it is therefore cot fully reliable.
OBSERVATIONS ON THE ZODIACAL LIGHT.
295
296 OBSERVATIONS ON THE ZODIACAL LIGHT.
Mo. 148.
APRIL 28th, 1854 : EVENING.
Lat. 34° 40' N.: Lon. 133° 59' E.
Sun set GA. 33m.
Stronger and Diffuse Light at 8/t. 30m. and 9A. 30»i.
Last evening the haziness of the atmosphere was so great that I could get no reliable boundaries. The sky, this
evening, was clear, except towards the horizon. Having been on shore till a later hour than usual, I was not able
to get observations till 8'1 30'"; when, and at !)'' 30'", I got boundaries. In consequence of the proximity of the Milky
Way to the horizon, and the haziness beneath, I was not able to make any observations for pulsations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
297
29S
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 149.
APRIL 29th, 1854 : EVENING.
Lat. 34° 40' N. : Lon. 138° 59' E.
Sun set 6A. 38m.
Stronger Light at 8A., &c. : Diffuse at 8 o'clock.
Morning hazy. Sky, this evening, clear in the west, at 8 o'clock. Grot observations at that hour. I thought, this
evening, that I could see pulsations distinctly even across the Milky Way. My notes are as follows :
h. m.
At 8 13, at b, and bright.
8 14J, at a, and dim.
8 15, do. very dim.
8 15^, brightening.
At 8" 18im, clouds began to float across the Zodiacal Light boundaries, and I could get no further observations. At
9h, sky quite clouded over.
The superior brightness of the Zodiacal Light over that of the adjoining portions of the Milky Way was, this
evening, very striking.
It. m.
At 8 16£, at c, and bright.
8 \*l\, do. and quite bright.
8 18|, do. do.
OBSERVATIONS OM THE ZODIACAL LIGHT.
299
38
300 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 150.
MAT 6th, 1854: MORNIKG.
Lat. aj° 40' N. i Lon, ias° 59' E.
Sun rose 6A. 10m.
ISA. 20m. -,
3 ^ i Diffuse 2A. 30»». and 3A 45ra,
3 50 j
Clouds nniformly since ray last date, until this morning. Was on deck at 2h 30™, and again from 3 o'clock till
dawn, watching carefully, and noting down boundaries as I could get them. But these morning observations are
very unsatisfactory. There is now always some haziness (the sun, at mid-day, not giving a full and clear light) ;
and the angle between the ecliptic and the horizon is small towards morning. Jupiter's light also produces
embarrassment. In my efforts at getting the upper end of the Zodiacal Light, I had to note clown portions of the
boundaries this morning, at different times, as I was able to make them out. It seemed to me that the Zodiacal
Light was more decided at 211 30m than at 3h 45a. Indeed, at the best, I should scarcely have known where to draw
the boundaries, if former knowledge had not come to my help. This morning's result, therefore, can scarcely be
considered an independent one. Dawn about 4 o'clock.
OBSERVATIONS ON THE ZODIACAL LIGHT.
301
302 OBSERVATIONS ON THE ZODIACAL LIGHT.
ISO. 151.
MAY 8th, 1854: MUKM.MJ.
Lat. 34'; 40' N.: Lou 13w> 50' E.
Sun rose 5/t. 8m.
Stronger Light s o ° kn ( Diffuse 3A. 30m. and 3A. 4.r>/n.
Zenith point at Sh. 45m.: Lat. 57° 25' N.: Lon. 291°.
Cloudy yesterday morning. This a. m. was on deck at 3" 10m ; the morning clearer than on the 6th, hut still
hazy. Boundaries tolerably distinct ; thought that the upper end of the Stronger Light terminated short of the
Milky Way, at the place marked by dotted lines in the chart ; hut was not certain, as Jupiter's light was dazzling to
the eyes. Towards daybreak, a very strong light began to show itself within the hue marked a a (3" 50'"). Day
dawned about 4 o'clock.
OBSERVATIONS ON THE ZODIACAL LIGHT.
303
304 OBSERVATIONS ON THE ZODIACAL LIGUT.
No. 152.
MAY 15th, 1854 : EVF.SIN...
Lat. at 8 o'clock, 40° 13' N. : Urn. 142° 52' E.
Sun set 7/j. '3m.
Strimger Light ' j'"' Diffuse Sk. 45m. and 9*. 15m.
Clouds uniformly since the 8th, except last evening (Sunday). This evening the sky was cloudless ; hut there
is now, clay and night, a haziness in the atmosphere ; and this interfered a little this evening ; but still I was ahle
to have a good observation. The Zodiacal Light began to show itself decidedly at 81' 27m ; but I was not ahle to get
boundaries till 8'' 40"'. Those of the Stronger Light would probably have extended up higher if the haziness had
not existed. For the same reason, I did not care about watching closely for pulsations. After 9'' SO"1, I was too
much engaged in looking for a Moon Zodiacal Light to take further boundaries in the west.
OBSERVATIONS ON TIIE ZODIACAL LIGHT.
305
gQg OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 153.
MAY 16th, 1854 : EVENINO.
Lat. at 8/1. 45m. 41° 50' N.: Lon. J41r' 8' E.
Sun set 7/». 8m.
( 8/1. 45m. )
Stronger Light? 9 25 .' Diffuse 8/1. 45m. and 9/i. Sow.
( 10 0 )
There is, now, a, constant haziness in the sky, much like that of our Indian summer ; and observations are, conse-
quently, not as satisfactory as formerly. The Zodiacal Light itself is fully distinct ; but there is some difficulty in
getting boundaries accurately. I do the best I can. At 10 o'clock, I thought the Stronger Light showed itself up
to llegulus ; but I do not give this as a certainty. The Diffuse Light is still more ill defined than the; other ; but
I put it down as it appears to me to be.
OBSERVATIONS ON THE ZODIACAL LIGHT.
307
39
308 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 154.
MAY 17th, 1854: EVENING.
Lai. 41° 47' N. : Lon. 140° 43' E.
Sun set 7A. 9m.
( 9A. Om.
Stronger and Diffuse Light? 9 30
t 10 0
Sky the same as last night. For the results, as accurately as I could get them, see the chart. The sudden ascent
of the Stronger Light between 9h and 9h 30m, as there given, was owing to a greater clearness of the atmosphere at
the latter time, which was continued also at 10 o'clock. At 10h 40m, the haziness had spread once more, and nothing
of the Zodiacal Light was then to be seen. The sky, at 9h 30m and 10h, was nearly or quite free from haze.
OBSERVATION'S ON THE ZODIACAL LIGHT.
309
- !
: -
IB
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310 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 155.
MAY 19th, 1854: EVEMNG.
Lat. 41° 47' N.: Lon. 140" 43' E.
Sun Set 7h. llm.
Stronger and Diffuse Light at 9 aud 10 o'clock.
Clouds last evening. This evening cloudless, but still a haziness in the sky. At 8h 45m, could see the Zodiacal
Light distinctly ; but I could not get boundaries till 9 o'clock. Even then, the limits both of the Stronger and Dif-
fuse Light were ill defined. At 9", the Light was pretty strong up as far as Castor and Pollux. At 10h, it was all
very faint, and I had great difficulty in getting boundaries ; think, however, that those in the chart for that hour
are tolerably reliable. At 10h 30m, there was nothing distinguishable.
OBSERVATIONS ON THE ZODIACAL LIG11T.
311
312 OBSERVATIONS 0>T THE ZODIACAL LIGHT .
No. 156.
MAY 211th, I .-54: EVKXINO.
Lat. 41° 47' N: Lon. 140° 43' E.
Sun set 7/i. I :!m
Stronger Light at !IA. 15m. and Jd/i. : Diffuse '.<h 3Um. and 10A.
Sky hazy as usual. Coulil not get any reliable outlines until 9*1 15'". The Zodiacal Light itself was very decided,
and was tolerably strong up to 16 Cancri ; but there was difficulty in making out the outlines. At 10\ the sky
was tolerably clear; and the Light was very distinct yet, at 10h 15m ; though the difficulty of getting boundaries still
remained.
OBSERVATIONS ON THE ZODIACAL LIGHT.
313
3J4 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 157.
MAY 22d, 1854 (21st was Sunday): MORNING.
Lat. 41° 47' N: Lon. 140° 43' E.
Sun rose 4A. 38<».
Stronger and Diffuse Light at 2A. 30m.
Zenith point at 2A. 30m. : Lat. C5n N. : Lon. 286°.
Owing to the clouds and moon, this was the first morning observation which I have been able to have in a long
while. The sky, on this occasion, was pretty free from the haziness with which it is now usually obscured. At 2h
3CP, the Zodiacal Light was very distinct, and its boundaries were easily got, except the lower part of the Diffuse
Light. In getting the upper extremity of the Stronger Light, I was troubled by the great brightness of Jupiter,
now at that spot ; but I put it, down in the chart as it seemed to me to be.
Moon rose at 2" 45m.
OBSERVATIONS ON THE ZODIACAL LIGHT.
315
2M fij l\(t
/../ l\0 |J \t> \S Jiff " /i.7 Z[O
11 I I I I I I I . 1 I > I I 1 I . ^ | , . I ! j ! I I I
40
316 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 158.
MAY 22d, 1854 : EVENING.
Lat. 41° 47' N. : Lon. 140° 43' E.
Sun set "ih. 14,Jm.
Stronger and Diffuse Light at 10/j. 1'Jm.
Sky pretty clear from haziness at 9h, except towards the horizon ; quite clear in the zenith. A change in the
appearance of the Stronger Light, which I have alluded to in recent entries, leads me now to make a slight change
in the mode of mapping. This Light is quite strong within the boundary a a (see chart) — as strong as the Stronger
Light has usually been. Above that, although evidently a continuation of the same light, it is so dimmed that it
can scarcely be recognized as a continuation of that Stronger Light ; and I have thus given two full lines for that
hour (9 o'clock). At 10'' 12m, the Light was very dim ; but I thought I could make out its boundaries as in the
chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
317
318 OBSERVATIONS ON T1IE ZODIACAL LK5HT.
'No. 160.
MAY 23d, 1854 I Monniffe.
Lat. 41° 47' N. : LOD. 140° 43' E.
Sun rose 4A. 37jm.
Stronger and Diffuse Light at 2/«. 40m
Zenith point at 2A. 40m. .< Lat. 64° 25' N. s Lon. 293°.
1'he sky was hazy on the horizon ; but the haziness diminished as it ascended, and, at 25° of altitude, was scarcely
perceived. In the zenith, the sky was clear and bright. The Zodiacal Light was very evident, and its boundaries
pretty well defined, except the lower one of the Diffuse Light. I thought, yesterday morning, that the Stronger
Light rounded off in the neighborhood of Jupiter ; but this morning it appeared to extend nearly or quite to the
Milky Way, and I have left its end undefined,
Dawn a few minutes after 3 o'clock.
OBSERVATIONS ON TI1E ZODIACAL LIGHT.
319
320 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. ICO.
MAV ^:>t1i. K.!: MOKMX-O.
Liit. 41° 4?'N.: LDII. I4'i° 4:',' K.
Sun ruse \h . '.' \ui .
Stronger ami Diil'iisi- Liylit. at ^h. anil 'J/i. -Kim.
Zenith pi ini ;:t vli: L;it (>.".- ,Y N. : Lcm. 289°.
Clouds uniformly since last date till this rnoruing. Rose a "little before 2 o'clock, ami found the sky overcast
above, and also a .stratum of clouds alonj;' the horizon, but \vit!i an interval between them of clear, bright skv, free
from haziness ; thus hail satisfactory observations. At that early hour the Zodiacal Light was very distinct. As
the hour progressed, the ecliptic tippruadird rapidly towards a parallelism with the hori'/.oii, and the upper limits of
the Zodiacal Light changed downwards, especially on the left. At the same time, the boundaries became less and
less clearly marked ; and at 2'1 30'" the Light itself was not as distinct, except at the north or left termination, as
at 2". At 2'' 38'" it was difficult to get the boundaries at all, and at 21' 45"' they were quite gone. Clouds then spread
over the space, and my observations (cased.
OBSERVATIONS ON THE ZODIACAL LIGHT.
321
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HBa
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322 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 161.
MAY 29th, 1854 : EYENINO.
Lat. 41° 47' N.: Lon. 140° 43° E.
Sun set 7h. 19m.
Stronger and Diffuse Light at 9A. 10m. and 10A. 30 m.
About 9'' 10ra the moon sunk behind some clouds near the horizon, and I was able to get an observation. Tbe sky
was very clear; "but the evening Zodiacal Light, though very distinct, has now lost much of its brightness, our latitude
being high, and the ecliptic having a low angle with the horizon. The brightest part was below the zigzag line, hut
still the Stronger Light could be traced up, as given in the chart. At 10'' 30"1 the Light could still be made out,
though it was dim. The Diffuse Light was now particularly faint — scarcely perceptible. I have given the outlines
as they appeared to be. At II1' 20m there seemed to be something of it left ; but I could not be certain.
OBSERVATION'S ON TUB ZODIACAL LIGHT.
323
T- >
•
•
-
-
•
'-
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41
324 OBSERVATIONS ON THK ZODIACAL LIGHT.
No. 1G2.
MAY 30il), 1314 : Mouxme.
Lat. 41° 4'.' N: Lon. 140° 43' E.
Sun rose <l/i. !i.i/H.
Stnini;pr an i Ditfusn Li^lir. at l/i. 50m.
Zenith point nt 4/<. 33m : Lat. b5° 15' N.: Lun. 2-5°.
At lh 45™ the Zndiacal Lii^Tit distinct, but faint. The sky clear and gor>l for oliservin^ ; hut Jupiter's li^Ht em-
^sus the o'nerver, an 1 pi-L'v;nts c,ji'tain limits bjinj; LCD^ at t\\i u ipjr on 1. T'ra Light was stronger within the
limits a a a n. ; at 2'' 20", it brightened considerably at its lower end, especially with u u u a. At 2h 45'" a cloud
came over, and put an end to observation.
OBSERVATIONS ON THE ZODIACAL LIGHT.
.125
33
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J26 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 163.
JUNE 2d, 1854: MORNWB.
Lat. 41° 47' N.: Lon. 140° 43' E.
Sun rose 4A. 3l^m.
Stronger Light at ' 3,™' Diffuse at 3A.
Zenith point at 2A. 3u/«.: Lat. 63° 10' N.: Lon. 303°
Fogs or clouds since the 30th ultimo. Was on deck this morning at lh 50", and found the slcy very clear, and the
Zodiacal Light distinct, though dim. At 2" got boundaries, as in the chart ; the lower boundary of the Diffuse, how-
ever, not fully reliable, but given as it appeared to be. At 2'' 30'" the Light had increased considerably in bright-
ness, especially at its lower end, and up to the boundary a a. At 2"1 3S11 still brighter, and the greatest brightness up
to the boundary l> b. At 2" 50'" a general whiteness in the sky, and could not get boundaries any longer.
At 2h the boundary of the Stronger Light, on the lower side, could be made out to c; at 2" 30'° it had extended to d.
OBSERVATIONS ON THE ZODIACAL LIGHT.
327
EB
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Er?
ej --
-
328 OBSERVATIONS ON THE ZODIACAL IIGHT.
No. 164.
JUNE f.rh, 18'A : MIIHNIXO.
Lat. 3;°34' .V : ty.n HI°53i'E.
Sllll IM-iH I/I 4 l/rt
Stronger ;mil D ff i*i> Lulu ni, 3 nVInr
Zenith P..iut at ->h.: L.it ol)0 :>;>' N.: L.m
Fogs, &c., since my last. Found on going on deck, at 2, a. ra., that t;ic- c'vui^e of a few degrees In our latitude
had sensibly lifted up the Z iliac il Light, and ha I undy it niujh ni'ire strikinj; a>id decided than at my lust observa-
tion. To this, the change in the atm >S|>here lia I d-mb less, also, (Mnti-ibut- 1 in s.nnj measure: lor the sky this
morning was remarkably brilliant. At first sight, and re;i -at ' lly a'ierrt-ards, I thoiig'it the iStron^i.-r fjig'it termi-
nated at a and ft Capricorn!; but of this c:ml 1 n >t b_' certiiu, on aa: nr.it of t!i-' gl.fe of Jn;i:ter. S.nneti ne.s
thought it continued on to t!ie Milky Way ; and I have marked both Hides iu t!ie eliart \vit!i dotted lines. ISo.jn after
2h, clouds came up and stopped observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
329
-
P Q
DB a
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= 3
ma
•~5~3
11
330 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 1C5.
JUNE 8th, 1854 : MOUSING.
Lat. 34° 39' N : Lon. 133° 39' E.
Sun rose \h 51m.
Stronger Light at \ j**' „"'"' I Diffuse, 3A.
Zenith point at 3A.: Lat. 51° 30' N.: Lon. 323°.
Clouds until near 3 o'clock, when I had a very clear, bright sky, excellent for observation. The Zodiacal Light
was very distinct, the change of latitude now m iking it ascend much higher in the sky than has lately been the
case. Got observations at 3 o'clock, and at 3h 20'" for the Stronger Light : the lower boundary of the Diffuse was
not very distinct at any time. Dawn at about 31' 28m. This comes now slowly, and by imperceptible degrees.
OBSERVATIONS ON THE ZODIACAL LIGHT.
331
42
OBSERVATIONS ON THE ZODIACAL LIGH7,
No. 16G.
JUNE 21st, 1854: EVENIKG.
Lit, 34° 39' N.: Lon. 138° 59' E.
Sun set 7/(. llm.
( Sh. 5dm.
Stronger and Diffuse Light at< !> 0
< 10 0
Clouds ever since last date, until this evening, when the sky was very favorable for observations. Owing to the
long twilight, however, I could not get boundaries until 8" 50'" ; at 9 o'clock the darkness had increased, and wider
boundaries were, consequently, visible. At 10'' the Light hail still considerable brightness ; but the ecliptic had
sunk so much towards the horizon that it was difficult to get reliable boundaries : I believe, however, that those given
may be depended on.
OBSERVATIONS ON THE ZODIACAL LIGHT.
=?
1
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OBSERVATIONS ON TEE ZODIACAL LIGH7,.
KO. i cr.
JUNE22d, 1854: EVEKH:?,..
Lat. 34° 40' N.: L.m. 13-° 5!)' E.
Sun set 7/i. lUni.
Stronger and Diffuse Light at 9 and 10 o'clock.
Sky clear, and good fur observations. Boundaries distinct at 9 o'clock ; at 9" 30m could not perceive finy
in them : at 10", as in the chart ; the Li«;htthen very distinct, and its outlines well defined . at 10'' 40'" the Lighl
still very decided, but eould get no reliable boundaries.
OnSERVATIONS ON THE ZODIACAL LIGHT.
335
336 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 1CS.
JUNE 21th, 1854 : EVKNINO.
Lat. 31° 4(1' N.l Lon. 133' 59' E.
Sun set 7A. 12m.
Stronger and Diffuse Light, 0 iinj 10 o'clock.
Storming all day ; cleaved up suddenly ; and at 9h p. m., the sky was remarkably clear and bright— th- ,".i
having been purified by the storm. With all this, however, there was sum:' difficulty in getting the boundaries at
the upper end of the Stronger Light, and still greater as ivsp;>cts the Diffuse Light throughout. At 10'1 the Zodiacal
Light was still very decided ; but I can scarcely set down the boundaries given to the Diffuse Light, ;it that hour, as
fully reliable, though the sky was still very clear. I give them as they appeared to me to be, without offering them
as a certainty.
OBSERVATIONS ON THE ZODIACAL LIGHT.
337
338 OBSERVATIONS ON THE ZODIACAL LIGIIT.
No. 169.
JUNE 27th, 1854 : EVENING.
Lat. at 9A., 33° 1' N : Lon. 136° 45' E.
Sun set "ill. 94m.
Stronger and Diffuse Light at 9 and 10 o'clock.
Zenith point at 9A.: Lat. 49° N.: Lon. 215°.
Last evening, clouds. Sky remarkably bright and clear, this evening. The Zodiacal Light distinct at 8h 40™ ; but
I could not get reliable boundaries till later. At 9h, as in the chart. At 10", sky still very clear, but the Light
much dimmed ; and it was difficult to make out the boundaries, especially beyond 94 Leonis.
OBSERVATIONS ON TIIE ZODIACAL LIGHT.
339
43
310 OBSERVATIONS ON THE ZODIACAL UQIIT.
NO. no.
JUNE 29th, 1854: MORMNO.
Lst. nt 3A., 30° 26' N. : Lon. 136° 52' E.
Sun rose 5A. 4m.
Stronger and Diffuse Light at 3 o'clock.
Clouds last evening. The moon, or clouds, in the morning, ever since my last morning date (8th instant).
This morning, at 2" 30™, the Zodiacal Light was quite distinct ; but, before I could note boundaries, the sky
was all clouded over. Waited until it might clear ; and at 3h was able to have a good observation ; the sky clear
and pretty bright. The boundaries of the Stronger Light were not very well denned, as it ran gradually into the
Diffuse Light, which is now brighter than it recently was ; but I think those given may be depended on. The
upper limits of the Diffuse Light could not be got, on account of the brilliancy of Jupiter, now in that region ; but
they may be inferred from the other portions..
OBSERVATIONS ON THE ZODIACAL LIGHT.
341
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342 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 171.
JUNE 29, 1854: EVKNING.
Lat. at KlA., 38 ^ 33' N.: Lou. 136° 21' E.
Sun set G/i. 57m.
Stronger and Difluse Light at 10 o'clock.
Last evening, cloudy. Moon did not set this evening till about U" 52'" ; then I got an observation (10 o'clock) as
in the chart. The sky was perfectly clear and brilliant down to the horizon. The Zodiacal Light was dim at this
hour, but quite distinct. The Stronger Light had well defined boundaries below a a ; above that, it dimmed off, till
at last it was difficult to ascertain its limits. In the morning observation, had been a new feature, namely : a
departure of the lower line of the Stronger Light from parallelism to the ecliptic ; and this evening I gave more
particular attention to what I had suspected several evenings past, namely : a tipping up of the apex of this Light,
so as to bring it to the right of the ecliptic line. J have put in the chart what seemed to be the termination ; but
the light there is so faint at 10'', that I cannot speak positively. I give it as, after long and careful and repeated
trials, it appeared to me to be.
At 10" 20m the Light was still distinct, as high as 29 Virginis, but dim ; its boundaries the same as at 10 o'clock.
OBSERVATIONS ON THE ZODIACAL LIGHT.
343
344 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 171
JUNE 3Uth, 1854: MORNING.
Lat. at 3A., 28° 22' N. : Lon. 130° IS E.
Sun rose oh. Him.
Stronger and Diffuse Light at 2A. 30m. and 3/i. 20m.
The sky this morning quite hrilliant, and excellent for observations. At 2" 30™ the Zodiacal Light very distinct ;
but the upper end is dimmed off to such a degree, that it is difficult to get boundaries there. I scarcely knew, this
morning, whether to put down boundaries to the Diffuse Light or not, they were so indistinct and uncertain ; but
I have done the best I could. The difficulty was still further increased by the brilliancy of Jupiter. As dawn
approached, say at 3h 25", the lower end of the Stronger Light grew very bright, but still kept strictly within the
boundaries given. This lasted till about 3" 40"', when the light spread, and dawn had come.
OBSERVATIONS ON THE ZODIACAL LIGHT.
345
346 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 173.
JULY 1st, 1854: MORNING.
Lat. at 3A., 27° 35' N.: Lon. 136° 8' E.
Sun rose 5A. 12m.
C 2A. Om. )
Stronger Light •? 3 0 }• Diffuse 2A. 45m.
( 3 30 )
Sun's Lon. 99° 15'.
Rose at 2", and found the Zodiacal Light quite distinct; the sky brilliant, hut the view interrupted by flying
clouds towards the horizon ; in the intervals between these, I was able, however, to get reliable boundaries. The
D'ffuse Light, however, was so dim, that I could not get boundaries till 2" 45m ; and even then, and afterwards, this
Light faded away so imperceptibly at its edges, that I had some doubts about trying to define it at all. The lower
end of the Stronger Light is always much brighter than the upper : it dims as it ascends ; and, at last, it is hard to
say where its apex is; but the lines got below, which are fully reliable, help, by their convergency, to guide us
along the less striking part above. Dawn about 3h 40'".
OBSERVATIONS ON THE ZODIACAL LIGHT.
347
348 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 1*74.
JULY 4th, 1854: MORNINO.
Lat. at 2A. 30m., 26° 51' N.: Lon. 132° E.
Sun rose 5A. 10m.
Stronger Light at 2/i. 30m.
Clouds since last date. Rose at 2h, but found the sky covered with flitting clouds. By watching, and catching
outlines in the intervals between the clouds, I was able, by 2" 2CP, to get the boundaries as in the chart. I think
they are reliable ; but the whole was so unsatisfactory that I made no further attempts. The Diffuse Light could
not be defined at all. The clouds, however, had one advantage, inasmuch as they, by contrast where the Zodiacal
Light could be seen, made it more striking, as they always do in such cases.
OBSEHVATIONS ON T11E ZODIACAL LIGHT.
349
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550 OBSERVATIONS ON THE ZODIACAL LIGHT.
No, 175,
JULY 6th, 1854 ; Mossms.
Lat. at 3A., 29° 50' N.: Lon. 130° 4!)' E.
Sun rose 5/t. 7m.
Stronger and Diffuse Light at 2k. 15m., and 3h. 15m.
* Sun's Lon. 103° 41'.
At 2 a. m. found the sky rather dull, but was able to get a reliable observation, except at the lower side of tho
Diffuse Light, which was hidden by a thick haze lying at that part of the horizon. At 3h 15m, the sky was brighter,
and I got more satisfactory results. I have put the upper end of the Diffuse Light in dots, as that portion was made
doubtful, both by the dimness of the Light and by the brightness of Jupiter.
OBSERVATIONS ON TUB ZODIACAL LJGIIT.
351
352 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 176.
JULY 6tb, 1354 : MORNING.
Lat. at 3/«., 29° 18' N.: L<m. 129° 37' E.
Sun rose 5/i. 10m.
Stronger Light \ }J'' jj^'"' j Diffuse Light l/i. 52m. and 3A. 10m.
Sim's Longitude 104° 1'.
Was on deck at half-past 1, and was surprised to find the Zodiacal Light so distinctly marked and so well defined.
Got reliable boundaries at 1" 35"' for the Stronger Light, but, on account of some flitting clouds, could not bound the
Diffuse till somewhat later. Again on deck at 3 o'clock, but found the sky now rather dull, and was not able to get
the lower boundary of the Diffuse Light reliably. At both observations, the upper extremity of the Stronger Light
was badly marked, but I believe the boundaries given may be relied on.
OBSERVATIONS ON THE ZODIACAL LIGHT.
353
-M-
OBSERVATIONS ON THE ZODIACAL LIGHT.
NO. m.
JULY 7th, 1854: MOUSING.
Lat. At 3*., 28° 56' N.: Lon. 127° 52' E.
Sun rose at 5A. ll.Jm.
Stronger Light at j ®'' j"'"' | Diffuse 3A.
Sun's Lon. 104° 58'.
Was not waked till 2h 30m : found the sky very brilliant, but broken by flying clouds. Between these, however, I
was able, finally, to get complete boundaries both of the Stronger and Diffuse Light. At 3h, was driven below by a rain
squall. This passed, and then had a good observation at 3h 15m. 1 am particularly careful now about the bounda-
ries, on account of the unusual course of the Zodiacal Light — for which see the chart. The observation at 3h 15m,
and also the boundaries of the Diffuse Light, I think may be considered fully reliable. Was somewhat puzzled, this
morning, by what seemed to be rapid changes in the width of the Stronger Light at its lower and mere decidedly
marked end, and suspect that they were pulsations; but though the sky was very brilliant, I had no opportunity
to decide on this matter. At 3'' 25"1 a heavy rain squall came up, and the sky was immediately all covered over
with clouds.
OBSERVATIONS OX TITE ZODIACAL LIGHT.
355
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ICU
856 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. ITS.
JULT 8th, 1854 : MORMNO.
Lat. at 3A., 20° 14' N.: Lon. 120° 26' E.
Sun rose at 5A. ll|m.
Stronger Light at | g*- .^"^ j Diffuse 3A.
Sun's Lon. 105° C.V.
The moon interfered, this morning, till 3 o'clock, when I was able to get an observation; the sky, though not bril-
liant, still very favorable. I have marked by the zigzag line the height to which the strongest part of the Stronger
Light appears to ascend, though it tapers off so gradually that it is difficult to draw a distinctive mark, while it is
evident that the Light below is much brighter than higher up. I thought several times that there were pulsations,
and on one occasion took notes thus : 3!l 26m, the brightest part dim and at a; 3h 28™, do.; 3h 29"', brightening : 3"
32m, at b, and brighter ; 31' 36m, do. do. But I cannot present these annotations as reliable ; the changes, if there were
any, being so uncertain, although I watched with the greatest care. Soon after 3h 36m commenced a permanent gradual
brightening ; and at 3" 43m dawn had come.
OBSERVATIONS ON THE ZODIACAL LIGHT.
357
358 OBSERVATIONS ON THE ZODIACAL LIGH7.
No. 179.
JULY ]3th, 1854: ETENIVS.
Lat 2.5° 9' N : Lon. 121° 40' E.
Sun ser G/i. 48m.
Stronger and Diffuse Lii ht at 9A.
Moon and thin clouds since my last, both morning and evening. The early part of this evening cloudy; but at 9s
I was surprised to fiud the sky clear and remarkably brilliant— very good for observations. Had a careful one at 9h,
particularly so as respects the angle which the Zodiacal Light seems now to make with the ecliptic. For result, see
the chart. The lower end of the Stronger Light, as high as about a a, is bright; above this, it goes tapering off, so
as at last to be very dim. Still, as I made repeated trials of observation, and always with the same result, I thinll
the outlines given may be relied on. Soon after 'J'1, clouds arose and prevented further observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
359
360 OBSERVATIONS ON THE ZODIACAL LIGHT,
Ho. 180.
JULY 14th, 1854: EVENIN*.
Lat. 25° 9' N, : Lon. 121° 46' E.
Sun set 6A. 4".im.
C fit. 15m.
Stronger and Diffuse Light at? !) 0
( 9 45
A clear and brilliant evening. Got observations at 8'1 15m, &c., as in the chart. At 9* the Stronger Light was dim
above 29 Virginia. At that time it possibly extended up to a. Librre, but I could nut be certain about it. At 9" 45m,
both Diffuse and Stronger Light quite distinct, aud at 10" also ; though the Stronger Light had then dimmed very
much.
OBSERVATIONS ON THE ZODIACAL LIGHT.
861
2 |j -liO IIS - 241
S62 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 181-
JULY 15th, 1854 : EVENING.
Lat. 25° 9' N. : Lon. 121° 46' E.
Sun set 6A. 48m.
Stronger and Diffuse Light at 8, 9, and 10 o'clock.
At 8 o'clock the Zodiacal Light was quite distinct ; but the upper end of the Diffuse was not easily made out; at
9\ the latter was better defined. The sky was remarkably brilliant. The upper end of the Stronger Light was
comparatively dim. I have given its boundaries, after very careful study. About 8h 3CP, this Stronger Light
seemed to have a rapid ascent, and brightening, from its former position at 8h. At 10" the Stronger Light had
dimmed very greatly, and its upper end was scarcely distinguishable from the Diffuse Light, which now was very
decided and well denned. At 10" SO™ the Stronger Light could not be defined at all, and the Diffuse could scarcely
be made out.
OBSERVATIONS ON THE ZODIACAL LIGHT.
3G3
46
364 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 182.
JULT 18th, 1854 (16th was Sunday): ETENIBC.
Lat. 25° 9' N. : Lon. 121° 46' E.
Sun set 6A. 47m.
Stronger and Diffuse Light at 9A. and 9A. 40m.
Last evening, clouds. Clouds this evening, also, till 9 o'clock, when I was able to have a good observation, the
sky being very bright. At 9" 40m the Light was very well defined, except the upper end of the Stronger Light,
where, however, my outlines, I think, may be fully relied on. The Diffuse Light was very well defined and very
distinct.
OBSERVATION'S ON TUE ZODIACAL LIGHT.
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866 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 183.
JULY I9th, 1854: EVENINO.
Lat. 25° 9' N. : L"n ]J]° 40' E.
Sun set O/i. 47m.
Stronger and Diffuse Light at f/i. 3:'»;. and OA 30m.
I was absent in a boat, and did not get back to the ship till 8'' 3(P, when I had a very good observation ; the
clear aud very bright— so also at 9" 30"' ; but at this latter hour, the Stronger Light had dimmed cousiderably.
OBSERVATIONS ON TEE ZODIACAL LIGHT.
SG7
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OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 184,
JULY 20th, 1854: EVENIKS.
Lat. 25°9'N.: Lon. 121° 40' li.
Sun set CA. 47/«.
( >-•//. 15m.
Stronger and Diffuse Light at< !) (I
( 9 30
The Zodiacal Light was quite distinct at 8" 15™. It seemed to be brightest of all at 9". The sky was very clear
and bright. At 9'' 30"1, took boundaries ; but the Light was then so dim that it was difficult to get them so as to be
fully reliable.
OBSERVATIONS ON THE ZODIACAL LIGHT.
369
370 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 185.
JULY2lst, 1854: EVF.NISO.
Lat. -25° !)' N. : L<.n. 1-21° 46' E.
Sun set. Hi. 4 <in.
Stniiiger auil DilFiise Light at 8/1 3'^m.
Was absent in a boat till 8'1 30"; then I ha I a very good observation. Sky very bright ; clouds arose soon after
this, and 1 got no lurther observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
371
/ 1 o. ;
i i i I i ' i ;
372 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 186.
JULY 22d, 1854: EFEKINO.
Lat. 25° 9' N. : Lon. 121° 46' E.
Suu set C/i. 46ra.
t 8h. 15m.
Stronger and Diffuse Light at? 9 15
( 9 45
Sun's Lon. 119° 17'.
Sky very bright and clear. At 8h 15m, the Zodiacal Light quite distinct. At 9h 15m, the Stronger Light was
dim, for that early hour ; but I was able still, at 9" 45m, to get boundaries, though the Light, both Stronger and
Diffuse, had very much faded.
OBSERVATIONS ON THE ZODIACAL LIGHT.
373
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374 OBSERVATIONS ON THE ZOMACAL LIGHT,
No. 187.
JULY 24th, 1651 (23d was Sunday): MORNINO.
Lat. at 3A.,25° 39' N.: L'in. 121° 37' E.
Sun rose 54. 2fim.
Stronger and Diffuse Light at iA. 30m. and 3A. 15m.
Moon in the morning since the 8th. Was on deck at 2'', and found the Zodiacal Light quite distinct ; hut on
account of flitting clouds, could not get boundaries till 2h 15"1. (Sky all clouded over at 3h, hut clear again at 31' 30'",
when I had a very good ohservation. The Stronger Light now, in the morning, is very hright . ; hut the Diffuse is
dim — just the reverse of what we have in the evening. Once or t*vice I thought that there were pulsations in the
intensity of the Stronger Light ; hut Venus is now so bright at the lower end of the Light., that it is difficult to tell.
Dawn about 4 o'clock.
OBSERVATIONS ON THE ZODIACAL LIGHT.
375
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378 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 188.
JULY 24th, 1854: EVENING.
Lat. at 8A., 25° 33' N : Lon 120° 39' E.
SUD set (iA. 46m.
C 8A. Om. ) ( 8/1. 15m. )
Stronger Light at { 8 15 V ? 8 45 > Diffuse.
( 8 45 ) ( 9 45 ^
Sky clear. At 8 o'clock the Zodiacal Light was quite distinct at its lower end, as in chart ; but the night had not
yet deepened sufficiently to show it further up. As the darkness increased, it ascended rapidly ; and at 8b 15'" the
boundaries were as given for that hour in the chart. It seems to be brightest at about 8h 45™. The Diffuse Light
is strongly marked, and I noticed again the contrast in intensity between the present evening and morning Diffuse
Light. At 9" 45m I could define this latter well, but could not get boundaries for the Stronger. The latter appeared
to have melted gradually into the Diffuse.
OBSERVATIONS ON THE ZODIACAL LIGHT.
377
378 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 189.
JULY25tb, 1854: MORNIMO.
Lat. at 3/i., 25° 31' N. : Lou. 120° 41' E.
S'm rose at 5/(. 27m.
Stronger and Diffuse Light at 2A. Mm. and 3A. 10m.
Was on deck at 2 o'clock, and found the Zodiacal Lig'ht very strong for that early hour. Sky bright and clear.
Another observation at 3' 10"; soon alter which, a mist overspread the sky.
OBSERVATIONS ON THE ZODIACAL LIGHT.
379
48
380 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 190.
JULY 25th, 1854: EVENISO.
Lat. at Sh., 25° N. : Lon. 120° 28' E.
Sun set 6A. 44«.
Stronger and Diffuse Light at Sh. J5m. and 9A.
Watched to see the first appearance of the Zodiacal Light. In the portion of the sky immediately over the sun,
now set, there lingered a reddish light till near 8 o'clock, when it faded rapidly away, and then a light, which had
just before begun to turn upward towards the left, became soon developed as the Stronger Zodiacal Light. Tliis,-
however, did not reach its full height till at 8" 15m, when I took its boundaries. It now had a more gradual ascent,
as the evening passed, till at 9h, its boundaries were up to a and ;3 Libra?. At 91' the Stronger Light had dimmed
considerably, and soon after it was scarcely, if at all, distinguishable from the Diffuse Light. At 10" the latter was
discernible, but I could not get reliable boundaries.
OBSERVATIONS ON TtTE ZODIACAL LIGHT.
381
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382 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 191.
JULY 26th, 1854: MORNING.
Lat. at 3A., 24° 24' N. : Lon. 120° 4' E.
Sun rose at ah. 2Dm.
Stronger Light at 2 and 3 o'clock: Diffuse at 3 o'clock.
Was up .at lh 30™, in order to see whether the Zodiacal Light was visible at that hour or not. The sky was
unfavorable, not being bright, and there were clouds also at the eastward. I thought the Zodiacal Light was
plainly distinguishable between the clouds ; but I could not get boundaries before 2 o'clock ; succeeded also at 3h ;
but both at 2 and 3 o'clock, the Zodiacal Light had a very singular appearance, such as I had never noticed
before. The Zodiacal Light is usually a clear transparent lisjht, with a slightly yellowish tinge ; and the stars,
which are behind, are but slightly dimmed by it ; but, on this occasion, it looked as if it had all been muddied.
The stars back of it were much dimmed or quite obscured ; while, on each side, though not shining with the bril-
liancy frequently seen (the sky a little hazy), they were as in other parts of the sky. 1 consequently got the
outlines, particularly of the Stronger Light, with more ease than I commonly do.
(P. S. 26th July, 10h a. rn. Sky overcast and threatening since sunrise.)
(P. S. 29th July. This was followed by a gale.)
OBSERVATIONS ON THE ZODIACAL LIGHT.
383
384 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 192,
JULY 29th, 1854: MORMNO.
Lat. at 3fi., 2(1° 41' K. : Lon. 114' 54' E.
Sun rose at 5/« 36/n.
Stronger and Ditfuse Light af-i, 3, and 4 o'clock.
Clouds since last date until this morning;, which was tolerably clear. I was up at 1 o'clock, and thought I could
distinctly recognize the Zodiacal Light at that very early hour ; but did not attempt to get boundaries, on account of
clouds flitting by. At 2'', 3'1, and 41', succeeded as per chart. The Zodiacal Light had the same unusual appearance,
this morning, that was noticed at the last date ; looking as if muddy water had been stirred into it. The stars in
its line were either blotted out, or obscured, to an uncommon degree. This morning, as at the last, the atmosphere
had a blight degree of haziness.
OBSERVATIONS ON THE ZODIACAL LIGHT.
3S5
m
m
-
-
386 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 193.
JULY 31st, 1854 : MORNINO.
Lat. at 34., 19° 29' N. : Lon. 116° 22' E.
Sun rose at 54. 39m.
Stronger and Diffuse Light at 3 and 4 o'clock.
Sun's Lon. 137° 53'.
The 30th was Sunday. Was not waked till 3 o'clock this morning ; found the sky very clear and bright. No
muddiness in the Zodiacal Light. Took boundaries very carefully ; those of the Stronger Light very distinct; of the
Diffuse Light, the limits were very badly marked ; and the Light itself was scarcely discernible, except near the Stronger
Light. I give its boundaries as they seemed to be, though perhaps they are not fully reliable. The boundaries
at 4b seemed to be the same as at 3 o'clock. In these morning observations I am troubled, while getting the bound-
aries of the Stronger Light, by wbat seems to be a rapid varying of the bounds, which can be occasioned only by
pulsations ; and I strongly suspect that there are such pulsations, but I am not able to catch them reliably. This
morning I was too weak, from sickness,* to observe for them long.
*This eicknees, which lasted six months, and is occasionally noticed in these annotations, was not occasioned by exposure in these observations, but by tho
sun, in my recent visit to Formosa, whither I was sent by the Commodore to make explorations for coal.
OBSERVATIONS ON THE ZODIACAL LIGHT.
387
388 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 194.
AUGUST lit, 1854: MORNIKO.
Lat. at 3A., 18° 35' N : Lon. 119° 32' E.
Sun rose at 5A 41m.
( 2A. Om. 1
Stronger Light < 3 15 > Diffuse at 2 and 4 o'clock.
(40 )
Sun's Lon. 128° 50'
Was up at 2 o'clock, and found the Zodiacal Light very distinct. Got boundaries easily, except for the Diffuse
Light, which was dim at its outer edge. At 3h, clouds ; but sky quite clear and bright from that to dawn.
Watched carefully through all the time to see if there were pulsations. Could not be certain, but rather think there
were. The difficulty in deciding is now increased by the brilliancy of Venus, and by the Milky Way, which crosse?
the Zodiacal Light towards its lower end. Have only the space about the Pleiades for observing pulsations : but
the width of the Zodiacal Light at that point seems to vary so often and rapidly, as to be accounted for only by
pulsations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
389
pi
390 OBSERVATIONS ON THE ZOIM.ACA!, LIGHT.
o
AUGUST 4th, 13)4. Moiwrso.
Lat at 3/i,17°4S'N : Lon 116°3rE.
Sun rose at 5A 43m
Stronger Light at 2/i Iflm oad S/i Jdm : Diffuse at 4 o'clock
Clouds since the 1st. Was up at 2 o'clock, and funnel the Zodiacal Light very distinct — quite bright. Flitting
clouds were very troublesome, but, by catching a portion of boundary here and there, as openings occurred, I was
able to complete the whole reliably. So, also, at 3h 45'". The clouds, however, prevented my 'jyttinj; boundaries of
the Diffuse Light, except at its lower end, at 4 o'clock,
OBSERVATIONS ON THE ZODIACAL LIGHT.
391
r
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392 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 196.
AUGUST 12th, 1854: EVENING.*
Lat. 14° 36' N: L™. 121s 2' E.
Son set ar (iA. 20m.
Stronger and Diffuse Light at 7A. 31m. and 8/(. 30m.
Clouds ever since last date (4th) till this evening, when the sky was pretty favorable for observations, which I had
at 7" 30™ and 8h 3CP, as in the chart. The lower end of the Light was shut out from me by houses, but the upper
part was distinct.
OBSERVATIONS ON THE ZODIACAL LIGHT.
393
3Q4 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 197.
AUGUST 17th, 1854: EVENING.
Lat. at Sk., 14C 19' N: Lon. 120° 40' E
Sun set at ti/i. \I'I\>H.
( 7h. 30m.
Stronger and Diffuse Light at< 8 30
/ 9 10
Clouds since last date, until this evening, when the sky was remarkably clear and brilliant. Had a good observa-
tion at 7" 30m : the Light had been distinct 10 or 15 minutes previously, but not sufficiently so to give reliable
boundaries. At 7" 30'", and till 8", the Stronger Light was very bright, particularly up to the zigzag line ; but it
also was very decided up to its extreme end. As the ecliptic, in these low latitudes, has risen up considerably in
the evening, I watched carefully from 7" 30"" to 9", to see whether there were pulsations, in either height or intensity ;
but I could not discover any. At 9" 10m, the Light was still very distinct and decided. In this latitude the stars
sink rapidly ; and by 10h, even Antares had got well down towards the horizon : I thought the upper end of the
Stronger Light could still be made out, extending as far as that star (Antares) ; but it was difficult to distinguish it
now from the usual glare along the horizon.
OBSERVATIONS ON TTTfi ZODTACAT,
8)5
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396 OBST5BVATION3 ON THE ZODIACAL LIGHT.
No. 198.
AUGUST 18ih, 1S:;4: EVEMXO.
Lat. at £A., U" 22' K.: L.m. 110° iii' E.
Sun set 6/1 \7m.
flh.30m 1
Stronger Light at { ~ <• Diffuse, ?/i. 30m.
i •' "
19 3!J J
Sky nnt at the brightest ; but I was able to get reliable observations at the times noted in the chart. Tried again,
very carefully ;md repeatedly, from 9'1 30"' to 9" 40'", to get boundaries ; but, thmigh the sky was now favorable, I
could not succeed. The Stronger Light was yet distinctly to lie seen, and senned to have travelled up as 1'ar as just
above Antares (as marked by dotted lines) ; but I could not determine this with certainty.
OBSERVATIONS ON TIIK ZODIACAL LKJIIT.
3 97
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 199.
AUGUST 21st, 1854 : MoRtwe.
Lot at 3A., 14° '27' N.: Lrm. 117° 16 E.
Sun rose at ?A. 50m.
C I A 15m. i
Stronger Light at< 2 15 > Diffuse 1/i. 15m. and 2A. 15.
( 3 15 )
Sun's Lon. 148° 3'.
(19th, clouds ; 20th, Sunday). Was up this morning at 1 o'clock, and found the Zodiacal Light qnite distinct,
but not giving very well marked boundaries. Some passing clouds interfered : I got boundaries at lh 15nl, which I
believe may be relied on ; also at 2" 13"' and 3'' 15m. At the last observation, the lower end of the Stronger Light,
as high as the zigzag, was brighter than the rest, to such a striking degree that I noted it on the chart. The
sky, this morning, was remarkably brilliant, and favorable for observations.
OBSERVATIONS ON Tlltf ZODIACAL LIGHT.
•
i
1 1
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4.00 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 200.
AUGUST 21st, lfr»4: EVENING.
Lat. at8A., 14° 41' N.: Lnu. 117° 12' E.
S:in set 6/1. Ili/n.
S( ranger an 1 Diffuse Light at lit. 30m. and 8h. 30m.
The slcy toleraViy clear a'il g»l. In the nb-ijrv itinn at 7'1 3r)'n, I took particular pain^ with reference to the
0[' tin: 1 >\\vr limit of t'n.' .Slron^ -r fji^'it, from a icirnll^listn with the ecliptic. At S'1 31)", tlie Light had
alrualv basome (liniui'l consi lerably, an 1 inii'li of its lower jtortion hal descemled belo'v the horiz in. At 'J'' IM"1
only a s!iu;'it ^efieral brig'itivss >M il I bj seen bjtwejn 9 Saarpioiiis and the horizon; aud, though I tried carei'ully3
no ix'liable boundaries could be uuule out.
OBSERVATIONS ON THE ZODIACAL LIGHT.
401
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B 9
402 OBfflEHVATIO^TS Off THE ZODIACAL LIGHT,
No. 201.
AUGUST 22d, 1854 : MORNIHO.
Lat. at 3/i,, U° 46' N.: Lon. 117° II' E.
Sim rase at 5A. 50«.
( I >,. d
ight at •? i 3»
(4 0
)
Stronger Light at •? i 3» > Diffuse 1A. and
(4 0 i
Suu's Loa. 145°.
Was up at 1 o'clock, and found tlie Zodiacal Light quite distinctly marked ; the sky being very clear and favorable
for observations. At 2'' JHV", the Diffuse apparently as before, but it was very dim, especially at its upper end. The
sliding over of the Stronger Light, as seen at 4", is very remarkable, and I must give further attention to it ; it was
so singular, that I did not enter the boundaries of this hour on the chart until after long and very careful observa-
tions. I had noticed also, at 2'' :W", that the Light bad concentrated much; i. e. was much brighter towards the
lower edge, or right-hand boundary given for that time. There was no great change in the angle of the horizon, to
account fur this sliding over at 4''. The Diffuse Light was very dim this morning, except at its lower end.
[18jG. I had not then thought of drawing the zenith lines, and I did not think of this till long after the above
date. They will account for the great sliding over of the boundary-lilies of the Zodiacal Light.]
OBSERVATIONS ON THE ZODIACAL LIGHT.
403
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eBSBRVATIONS ON THE 2ODIACAL LIGHT.
No. 202.
AUGUST 22d, 1854 : EVENING.
Lat. at eh., 15° 45' N.: Lon. 116° 36' E.
Sun set 6A. ]6m.
Strougcr Light at 1h. 30m., &c., to 9h. : Diffuse 7A. 30m. and 8h. 30m.
Evening very bright and clear, and favorable for observations. At 7h SO™, got boundaries as at a a — strongest
below the zigzag line. The Light began to show itself somewhat suddenly at about 7" 20°, but did not give reliable
boundaries till at the time noted above. After 7" SCP, I was watching the Light — not, however, in the slightest
degree expecting pulsations, the ecliptic being then low towards the horizon — when I began to suspect that there
•were sudden changes, both in the intensity and limits of the Stronger Light, especially in the former. I soon became
so well satisfied of such pulsations, that I began to take notes of the succeeding ones, which are as follows :
h. m.
h. m.
* # * #
At 7 52^, dim — boundary as at a a.
7 53£, brightening.
7 54-5, bright — boundary as at b b.
7 5fi, dimming.
7 57, quite dim, boundary as at a a.
(There is no mistake on the subject.)
7 53, brightening.
7 59, do. slowly.
At 8h 30™, still at b b; still tolerably bright,
longer be made out in a reliable manner,
o
a
a "
05 -
At 8
8
8 6
8 8
8 10
0, tolerably bright.
Si, there still seem to be pulsations ; but they are
so slight, I cannot get them confidently.
6, bright, and at b b.
8^, do. do.
do. do.
Seemed to continue permanent in this bright-
ness, and at b b.
At 9", the Light still observable, but the boundaries could no
OBSERVATIONS OM THE ZODIACAL LIGHT.
405
40G OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 203.
AUGUST 23d, 1854: MORNISS.
Lat., at 3*., 16° 0' N. : Lnn. 116° 26' E.
Sun rose at 5A. 49m,
Stronger Light at midnight, 2/i. and 4/;. : Diffuse at midnight and 4 o'clock.
Sun's Lon. 149° 58'.
I wished to see at how early a time the eastern Zodiacal Light would show itself, and went on deck at midnight ;
but the Zodiacal Light had even then got the start of me, and was quite distinctly displayed. I took boundaries of
it, as given in the chart ; also, at 2 and 4 o'clock. At 21', though the Stronger Light may be said to have its limits
as marked for that hour, there was a much brighter part of it within the limits of the zigzag a a a — the same as is
referred to in yesterday morning's record. But there was no sliding over of the Light this morning, as mapped
yesterday.* It is, indeed, difficult to say where the outlines of the Stronger Light are, for, from that brightness
within a a a, it dims off rather gradually till we reach the outer limits of the Diffuse Light ; and these are now so
indistinctly marked in the morning sky, that I sometimes hesitate about marking the boundaries of the Diffuse at all ;
but, though somewhat doubtful toward their upper end, they are not so at the lower ; and, by taking these to assist
as my guide along the sky, 1 made out to complete them as given in the chart.
a 1856. A closer reference to the chart will show that there was, to some degree, though it was not so striking as on the 22d.
OBSERVATIONS ON THE ZODIACAL LIGHT.
407
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if
408 OBSERVATIONS ON TEE ZODIACAL LIGHT.
Ho. 204.
AUGUST 23d, 1854 i ETESI.-.-H.
Lat., at Ph., 17° 59' N. : Lon. 115° 42' E,
San set at 6A. 174m.
Stronger Light at 7A. 30m. and 7h, 50m : Diffuse at 7k. 50m.
Sky not favorable ; a haziness along the horizon, and also passing clouds. I commenced getting snatches of
boundary-lines at 7h 30m, and finally completed them. After 7h 50™, clouds came up, and, with the haziness, pre-
vented further observations. The same cause prevented my seeing pulsations, if there were any.
OBSERVATIONS ON THE ZODIACAL LIGHT.
409
m
410 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 205.
AUGUST 24th, 1854 : MOKNING.
Lat at 4A., 18° 36' N. : Lon. 115° 26' E.
Sun rose at 5A. 47£m.
Stronger Light at 4/>. and 4/<. 3J'». : Diffuse at 4A.
The orderly at the cabin-door forgot to wake me as directed ; and, in consequence of the loss of sleep for several
nights previous, I did not awake of myself until 4 o'clock. The morning, however, was not very favorable, the sky
being troubled by flitting clouds. I have neglected yet to mention that, while the evening Zodiacal Light is much
shorter than the morning, its upper boundaries are far more distinctly marked, and particularly its apex.
OBSERVATIONS ON T11R ZODIACAL LIGUT.
411
52
412
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 206.
AUGUST 25th, 1854 : EYEKIHO.
Lat. at Sh., 20° 47' N : Lon. 114° 32' E.
Sun set at (i/i. 19»n.
Stronger Light at s g ^"' > Diffuse Light at 8A. 30m.
Clouds since yesterday a. m. until this evening. Was prevented by the same cause, on this occasion, till 7h 42m,
when, the clouds leaving the sky very favorable, except quite at the horizon, I had a good observation, and looked
carefully to see if there were pulsations. The records I took at the time are as follows : 7'1 42"' being at a a, as in the
chart.
h. m.
At 7 47, at b, and bright.
7 49, at a, and dim.
7 50^, at b, and bright.
to 7 53, at do. do.
h. m.
At 7 54, quite bright, and at b.
7 55^, do. do. do.
8 0, at b, and not so bright.
8 Of, do. and bright ; and so it remained.
I offer these notes of changes, however, with hesitation, inasmuch as these apparent changes were not clear and
decided, and of a fully satisfactory character. I give them as what they seemed to me to be.
At 8h 30™ the sky was quite brilliant ; at 9" 30m the boundaries were apparently the same as at last observation.
The Light was quite perceptible, but"1 was, however, very dim at this hour. I had an observation of the eastern
Zodiacal Light at 11 o'clock (for which see next morning's entry — 26th).
OBSERVATIONS ON THE ZODIACAL LIGHT.
413
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414 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 207.
AUGUST 26th, 1854: MORNING.
Lat. at 34., 21° 0' N. : Lon. 114° 18' E.
Sun rose at 5h. Vim.
I 1U. of 25th 1
Stronger Light at-? 3 of 2Gth > Diffuse, 2A. Om. and 4h. Om.
( 4 }
Sun's Lon. 152° 50': Zenith point at ll/i. p. m. of 25th: Lat. 34° 15' N. : Lon. 332° 30'.
Sky very clear and brilliant. I was anxious to see at what time the earliest certain exhibition of Zodiacal Light
in the east could be made out, and looked carefully in that quarter at 10h last evening ; but nothing of it could be
recognized. At 11 o'clock, went again on deck ; and now the eastern Zodiacal Light was very apparent and decided.
Lieutenant P had charge of the deck at that hour ; and on his coming over to where I was observing, I
directed his attention to that part of the sky, and asked him whether he could distinguish the Zodiacal Light. He
answered, " Oh yes, I can see it very plainly." The sky was very fine for observations. The intensity of the Light
about 48, 57, and 58 Tauri was at 11" 15m equal to that of the Milky Way at 27 and 13 Persei, or anywhere
between Algol and 33 Persei. (For morning observations, see chart.) The Zodiacal Light at 3" and 4" is now
extremely brilliant ; but the several parts melt away so gradually, that it is difficult to get boundaries except at the
lower end.
OBSERVATIONS ON THE ZODIACAL LIGHT.
415
416 OBSERVATIONS ON THE ZODIACAL IIGHT.
KTo. 20§,
AUGUST 28th, 1854 t MORKWC,
Lat. 22° 18' N. : Lon. 114° 10' E.
Sun rose at SA. 4'im.
I UA.3llm,e>f 27ih )
Stronger Light at 2 d 3 I of 28ih > DifFjee, 2A. 30m. and 4h.
( 3 3D " )
Om,
>
Sun's Lon. 151° •
27th was Sunday. Had observations, this morning, as in the chart. Sky clear and good ; and the Zodiacal Light
quite distinct in the east at 11 o'clock.
OBSERVATIONS ON THE ZODIACAL LIGHT.
-3 - ri
4 1 8 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 209.
AUGUST 29th, 1834: MORNING.
Lat.22° 18' N. : Lon. 114° 10' E.
Sim rose at ah. 4"m.
Stronger and Diffuse Light at 2 and 4 o'clock.
Sim's Ion. 105° 44'.
Sky in the evening dull: towards morning, very clear and bright. Got observations at 2 and 4 o'clock. The
upper termination of the Diffuse Light is very uncertain ; and I am guided, in drawing it, chiefly by the convergence
of the lines as seen lower down. Its track (i. e., of the Diffuse Light) across the Milky Way is now evident. I
looked to see whether there might be pulsations ; but if there are any, the Milky Way, crossing the zodiacal path
below, would make it difficult to detect them.
OBSERVATIONS ON THE ZODIACAL LIGHT.
419
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<]'20 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 210.
AUGUST 31st, 1854 : MORSKC.
Lat,22°16' N. : Lon. 114° 10' K.
Sun rose at 5//. 45m.
C ll/i,3(lm. of 3flth )
Stronger Light at < 1 15 of 31st > Diffuse 1A. 15m.
( 2 45 >
Sun's Lon, 157° 42',
Clouds since my last date. Clear this night till towards morning. At llh 30ra could easily make out boundaries
of Stronger Light in the east, and could see the Diffuse Light; but the latter was too dim to give reliable bounds.
Did not wake, after 2h 30™, till towards dawn, when clouds prevented any observation.
OBSERVATIONS ON TlIU ZODIACAL LIGHT.
421
--
•
-
422 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 211.
SEPTEMBER 4th, 1834 i Monsisc,
Lat, 22° 18' N, : Lon. 1 i 1° 10' E,
Pun rose at 5A, 48m,
Stronger Light at j ^'' '^)"'~ J Diffuse at 3h. 45;n,
Sun's Lon. 161° 35'.
Clouds since my last date, until this morning. Moon set about 3h 30m, when I obtained an observation. The sky
was bright, and the Stronger Zodiacal Light quite so, especially up as high as the Milky Way. I watched for an
hour, to see whether there were pulsations. Sometimes felt pretty certain that there were such, in intensify of the
Light ; and two or three times, made records of such apparent changes ; but I cannot speak of them reliably, and
therefore omit them here.
Dawn about 4" 38",
OBSERVATIONS ON THB ZODIACAL LIGHT.
428
424 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 212.
SEPTEMBER I2ih, Idj-l : EVENING.
Lat. at ~h 30m., 22° 15' N. : Lon. 115° 4' E.
Sun 8ft li/i. •>//<.
Stronger and Diffuse I.i^lit ac 7A. 15'«. aad "A. 45m.
Clouds ever since last observation (September 4th j, until this evening: sky, to-night, very clear and brilliant.
The Zodiacal Light quite distinct. The ecliptic has got down to a low angle with the horizon ; and there was, this
evening, a slanting off of the Stronger Light, as in the line a a. in the chart. This Light oft" to d d, was, I think,
decidedly Zodiacal ; for there was no such Light along the horizon, on either side of '/ if, or c c ; it terminating
abruptly at both places, and at d by a sudden curve towards the horizon. While this Light between b b, and a a,
was strong enough to come within the name of the Stronger Light, that between a: x, and c c, was still stronger, and
I could distinctly see the old Stronger Light keeping along its old straight course a; a?; this new addition being
evidently an extraneous thing. Eeiug at sea, 1 bad a ele.ir open horizon; and the night, remarkably clear, was very
favorable lor observations. Of the Stronger Light, decidedly the brightest part was below the zigzag.
At 8h 45m there was still a remnant of the Stronger Light ; but the bounds of both this and the Diffuse were now
too indistinct tii be made out reliably.
OBSERVATIONS ON THE ZODIACAL LIGHT.
425
426 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 213.
SEPTEMBER ]3th, 1854: EVENING.
Lat. at PA., 23° 4' N". : Lon. 1 10° 47' E.
Sun set at Gli. "Am.
Stronger and Diffuse Light at 7h. 15m. and lit. 45m.
Sky bright and clear. Paid particular attention to the off-shoot a a, of the Stronger Light ; but its character, as
apparent Zodiacal Light, was not so striking as at the same hour last night ; there being now a little haziness along
the horizon. Still, the sudden termination of this Light on the right hand was very obvious ; the horizon, both on
right and left, beyond the limits marked, being dark. I paid particular attention, also, to the boundaries of the
Diffuse Light, and took them carefully. The Stronger Light was strongest up to the zigzag line at x, and was not
well marked at its upper end. Its old course down the ecliptic was distinct, notwithstanding the adjunct Light
towards l> b. I neglected to take (his last at 7h 45™.
I was tolerably certain that there were pulsations. The dimming was very rapid ; but the brightening up again
was so very slow and gradual, that it was nearly, if not quite, impossible to note it reliably. I made the following
notes :
7*. m.
At 7 35, almost gone.
7 43, dim.
7 47, bright again.
h. m.
At 7 28, bright.
7 29i, dimmed.
# # #
7 34, bright.
7 34^, sensibly dimmer.
The asterisks designate periods during which I was not certain enough to feel authorized to mark changes, though
they seemed to be going on.
At 8h 10m the Light was still very distinct, but its outlines could not be got reliably. At 9h, nothing more could
be fully made out, though the Diffuse Light seemed to be still evident.
OBSERVATIONS ON THE ZODIACAL LIGHT.
427
54
428 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 214.
SEPTEMBER 14th, 1854: EVENISO.
Lat. at n, 30m. , 24° 5' N. i Lon. 118° 4K E,
Sun set at 6A. 2m.
ronger and Diffuse Light at 7h, 20»i. and ?A. 5flm,
1 am inclined to think that the adjunct Light to b b and a a is only a reflection from the atmosphere ; yet there
are some things about it antagonistic to this idea. I watched this evening, so as to observe it carefully from the
first. After sunset, there was a reddish horizon light (evidently twilight), yet extending only from c to d (see
chart on the horizon of 7h 20m), and terminating somewhat abruptly at those points. As- the evening grew on, this
redness gave place to a whitish light, keeping the same extent on the horizon, but increasing in breadth, till at
7'1 20'" it had the boundaries b b, as in the chart, being double the width of the first reddish light. But this
increase in width may have been owing to the increasing darkness of the sky, making positive light more obvious.
The Zodiacal Light, strictly so, was distinct at 7h 10m3 but did not give boundaries till Y1' 20'". Looked for pulsa-
tions, but could not see any.
OBSERVATIONS ON THE ZODIACAL LIGHT.
429
430 OBSERVATIONS ON THE ZODIACAL L1GUT.
No. 215.
SEPTEMBER Ifnh, 1854 : EVESIHO.
Lat at 7*. 30m., 27° 31' N, : Lon. 124° 23' E.
Sun set at 6 o'clock.
Stronger and Diffuse Light at 7h. 20m, and 7A, 40m.
Last evening cloudy. This evening, clouds interfered till 7h 20m, when I had a good observation. The Stronger
Light was brightest np as far as the zigzag ; above that, it was dim for it. About a. Libras the light was (7h 25m) as
strong as in the Milky Way at 57 Scorpionis ; at the same time the strongest light in the adjunct portion below a a
was equal to that of the Milky Way between 36 and 26 Scorpiouis. At Yh 401" the Stronger Light was quite dim at
its upper end, but bright at its lower. At 71' 45"', difficult to make out its boundaries. At 8h 15m the Zodiacal
Light was very decided within the Diffuse boundaries, as given on the chart ; but no Stronger Light could be made
out. At 9" 20m the upper end of the Diffuse Light was still left apparently, but was not reliable.
OBSERVATIONS ON THE ZODIACAL LIGHT.
431
432 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 216.
SEPTEMBER 19th, 1854: MORKINO.
Lat. at 2h., 29° 50' N. : Lon. 131° 31'.
Sun rose at 5/i. 51m.
Stronger Light at Ih. 20m. aud 2A. 15m.: Diffuse \h. &m,
Sim's Lou. 170° 11'.
(17th was Sunday.) Cloudy last evening. Moon in the morning until this a. in. Was on deck at 1 o'clock, and
found the Zodiacal Light very distinct at the lower part ; dim at the upper end. Sky very brilliant, Lut was
troubled by passing cirri. -Moon rose not long after the second observation.
OBSERVATIONS ON THK ZODIACAL LIGHT.
433
-?s
; -; =
=L^g
gg
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434 OBSERVATIONS ON THE ZODIACAL LIGHT.
No, 217,
SEPTEMBER 20th; 1854: Mofinme.
Lat. at 4A,, 32° 6' N. : Lon. 135° 8' E.
Sun rose at S'i. 51^™.
Stronger Light at It*. 30m. of 19th, and 4/i. of 2f)th : Diffuse 4/i.
Sun's Lon, 177° 10'.
Clouds in the west last evening. Was on deck for an eastern observation at 11 o'clock ; and the Zodiacal Light
there, though dim, was quite decided at that time. Shifting clouds, however, prevented my getting outlines until
11" 30m. Clouds prevented all further observations until 4h a. m., when I had a good one, except that the clouds
shut out the view near the horizon. The sky above was very bright.
The moon, after rising, was hid by the clouds on the horizon, ami I had o1,«f>rvn.t,ioris later than could otherwise
have been procured.
OBSERVATIONS ON THE ZODIACAL LIGHT.
435
43 G OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 218.
SEPTEMBER 20th, 1854: EVENING.
Lat. at 8k., 33° 27' N. : Lon. 137° 40' E.
Sun set at bh. SG^ro.
Stronger Light at 7h. lorn, and 7k. 45m. : Diffuse 7/i. 20m., 7h. 45m., and 8k. 30m.
Zenith point at 7k. 20m , Lat. 54° 50' N. : Lon. 299°. At 8A. 30m., Lat. 50° 20' N. : Lon. 323°.
Sky good for observations, except a few thin clouds along the horizon, just over the sun. Got boundaries at 7"
15m, which I believe may be relied on ; but the Stronger Light, within the old boundaries, was dim for it. At
7" 45m this Light, within the old bounds, stronger than before, and well defined; while the light below a a has faded,
except above b b; but whether thin clouds may be intervening, and so may produce this latter result or not, I
cannot tell.
Last evening, though I could get no full boundaries, I still was able to catch glimpses of the Light here and
there ; and, towards S'1, 1 thought that the Diffuse Light could be seen across the Milky Way. Mr. G-— — was sitting
with uie, and, on my drawing his attention to it, he saw it also. This evening I gave particular attention to it, and
the result is in the chart. The evening Diffuse Light is now very strong, and strengthens as the night advances,
to a certain period ; but still this boundary across the Milky Way may have some doubts attending it, on account of
the brightness of Jupiter, which planet is now within these bounds. At 8h 30m all was gone except the Diffuse
Light, which was still quite distinct.
OBSERVATIONS ON THE ZODIACAL LIGHT.
437
438 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 219.
SEPTEMBER 2Ut, 1854 : MORNING.
Lat. at 2/i., 33° 54' N.: Lon. 138° 1' E.
Sun rose at 5A. 51m.
, ( ll/i. 30m. of 20th. ) „.
Stronger Light at ^ 2 0 Qf 2]st £ Di
Sun's Lon. 178° 9'.
Looked out eastward at half-past 10 last evening, but could see no Zodiacal Light ; was on deck again at 11" 30"%
and then found it quite distinct, its boundaries as in the chart ; it was dim, but still very decided. Had another
observation at 2 o'clock. Sky very bright and favorable. The Stronger Light was stronger from the horizon up to
the Milky Way ; but above that, also, it could easily be made out. I intended to have another observation at 4", but
clouds prevented.
The morning Zodiacal Light is now very bright and striking.
OBSERVATIONS ON THE ZODIACAL LIGHT.
439
440 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 220.
SEPTEMBER 23d, 1854: EVENING,
Lat. 34° 40' N.: Lon. 138° 58' E.
Sun set at 5/i. 52£m.
Stronger Light at 7A. 30m : Diffuse J g ' gg
Clouds since last observation : to-day the equinoctial storm ceased, and was succeeded by a brilliant sky ; but some
cirri prevented my getting an observation till 7" 30m. The old boundaries of the Stronger Light are now badly
marked. At 8h 30m only the Diffuse Light could be seen; but this was quite distinct.
OBSERVATIONS ON THE ZODIACAL LIGHT.
441
442 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 221.
SEPTEMBER 27th, 1854: MORNING.
Lat. 34° 40' N. : Lon. 138° 58' E.
Sun rose at 5h. 56m.
( Hh. 30m. of 2Gth. ) ( g,
Stronger Light at { 2 10 of 27th. > Diffuse < f'1 '
(40 ) ( 4
Sun's Lon. 184° 2'.
Clouds since last date, except Sunday evening. This morning perfectly clear, and sky very brilliant. Had an
eastern observation half an hour before midnight : the Zodiacal Light fully distinguishable: though dim, still quite
decided at that hour. At 4'' the Stronger Light was much the brightest from the horizon up to the zigzag : the upper
terminations of Stronger and Diffuse Light could not be fully made out, and I have marked the places with dots, where
by inference we may believe them to terminate. After 4'', I watched carefully to see whether there were pulsations
or not ; was pretty certain sometimes that there were ; at others, was doubtful. Took record of some things that
appeared to be changes in intensity of light, but it is all so uncertain, that I am scarcely willing to offer the record.
Thus : 4" 22"', very dim ;
* * bright ;
4" 25"', dim ;
4" 27 tm, bright.
OBSERVATIONS ON THE ZODIACAL LIGHT.
443
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444 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 222.
SEPTEMBER 28th, J854: MORNING.
Lat. 34° 40' N.: Lon. 138° 58' E.
Sun rose 5/i. 57m.
Midnight, j
Stronger Light at <( 2/i. dm. V Diffuse 2A. Om. and 4A. Om.
i Midnight
Light at ? 2A. dm.
(4 (I
Sun's Lon. 185° 1'.
A clear, brilliant night. Had an observation at midnight, and gave particular attention to it with reference to
the change in the direction of boundaries between 11 and 12 and at 4 o'clock. The result is in the chart. The Lisrht,
at midnight, was dim, but very distinct. Observed also particularly with regard to the upper end of both Diifuse
and Stronger Lights at the different hours. At 2", could make out the termination of the Stronger Light ; the
Stronger Light at 4' was far brightest below the zigzag.* The sky was remarkably brilliant.
At 4h the fowls on board began to crow, deceived, probably, by the brilliancy of the Zodiacal Light, though it
was yet three-quarters of an hour short of dawn.
* By inadvertence, this was neglected in this engraved chart. The upper end of the zigzag was at Ion. 110°.
OBSERVATIONS ON THE ZODIACAL LIGHT.
446
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446 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 223.
SEPTEMBER 30th, 1854 : MORNING.
Lat. 34° 40' N.: Lon. 138° 58' E.
Sun rose 5/i. 57/n.
Stronger and Diffuse Light at 3/i . 20m. and 4h. 20m.
Sun's Lon. 186° 59'.
Clouds yesterday morning. Clouds also last night, and until 3h 10m this morning, when the sky became clear,
and good for observation. But still the Zodiacal Light this morning, from some unobservable cause, was not as
bright as I should have expected. Got boundaries as in the chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
447
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448 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 224.
OCTOBER llth 1854s EVENING,
Lat. at 7k., 35° 24' N. : Lon. 1G5° 16' E,
Sun set 5h. 27m.
StroDger Light at 7A. 12m. aud 7/i. 37m. : Diffuse 7h. 2nm.
Zenith point at 7h., Lat. 53° 25' N. : Lot). 319°.
Clouds ever since last date (September 30th), until this evening, when, soon after sunset, the sky became quite
clear and remarkably good for observations; the western horizon being particularly free from haziness down to the
water's edge. I was glad of this, as I wished much to have an evening observation at this time under favorable cir-
cumstances, and they were now as good as could possibly be. Sky quite clear and brilliant, and the horizon open
and clear. The results were interesting.
I watched carefully from the beginning. After the sun had set, its light lingered above it for some time, equally
on each side. This was evidently atmospherical light. Then the light appeared gradually and imperceptibly to
slide to the southward ; and, as the darkness increased, at 6h 55"', a white light, very decided, showed itself within
the dotted boundary a a. This light was strong to the horizon, and was different from any thing seen beyond it on
the north or south ; although, northwardly, a whitish light continued on near the horizon. By 7'1 12"' the darkness
had become complete, and the light had now changed. I could make out the boundaries b l> b l> ; I thought them
pretty distinct, the horizon being still remarkably clear. At 7" 20'", the light bounded by a a had widened, and had
become the Diffuse Light, with boundaries (c) as in the chart. (In making out the extreme end of this, I found
Jupiter's light troublesome, but believe I have got the true boundaries, notwithstanding.) At 7h 37m, I was con-
firmed in my belief that I had, at 7" 12m, got the boundaries of the Stronger Light, by finding that the upper
boundary had now slid up to d d, changing its direction in consequence of the change of angle in the horizon. I
could see it also extending across the clear interval in the Milky Way. At 7h 42"°, Diffuse Light on left of Milky
Way now quite decided ; boundaries as before. At 8 o'clock the Light could be seen, but was too dim to give bound-
aries.
OBSERVATIONS ON THE ZODIACAL LIGHT.
449
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450 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 225.
OCTOBER l-'th, 1S54: EVENING.
Lat. at7A.,35° 33' N.: Lon. 169° 18' E.
Sun set at 5A. 2fim.
Stronger Light at 7h. 30m. : Difl'uee ~h. 20m. and ~/i. 4«m.
Zenith point at 7k. 3()m. : Lat. 50° 8' N. : Lon. 330° 30'.
This evening was not so favorable as the last. There was a permanent stratum of clouds near the horizon, with
passing cirri higher up. By watching carefully, I was able, however, between the clouds, to catch boundaries, and
to complete them as in the chart. The boundary of the Stronger Light cannot be fully depended on, as it is at best
badly marked, and requires more deliberate observation than I was able to give it, in order to be entirely reliable.
It is here offered as it seemed to me to be. When Jupiter was obscured by small clouds, the Diffuse, on the left of
the Milky Way, was very perceptible.
OBSERVATIONS ON THE ZODIACAL LIGHT.
451
452 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 226.
OCTOBER 14th, 1854: ETEKISO.
Lat. at 7A. 15m., 33° 46' N. : Lon. 175° 52' E.
Sun set at 5A. 2im.
Stronger Light at 1h. 15m.: Diffuse 7/j. 15m. and 7A. 45m.
Zenith point at 7A. 15™.: L«t. 49° 10' N. : Lon. 327° 30' : At 7A. 45m.: L.t46°3;/ N. : Lon. 336°.
Clouds last evening; also this evening until vh 15"', when I had an observation: sky good. There was a
brightness, of uncertain character, below the line b b. The line given as for Stronger Light, at 71' 15'", was
so imperfectly marked in the sky, that I hesitated about drawing it. There is evidently a streak of unusual
brightness between this line and Antares, stretching in the usual course of the Stronger Light, and crossing
the blank space in the Milky Way ; but its upper boundary is badly marked, and its lower one is now usually
hidden by clouds, or blotted out by haziness on the horizon.
OBSERVATIONS ON THE ZODIACAL UG1IT.
453
.
454 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 22T.
OCTOBER 16th, 1854: EVENING.
Lat. at 7A., 33° 16' N.: Lon. 178° 21' W
Sun set 5/i. 22.Jm.
C Gli. 50m. )
Stronger Light at < 7 0 /Diffuse 7h. Om. and 7h. 40m.
( 7 40 )
Clouds last evening. The sky this evening very favorable for observations, and I had one at 6" 50m. Thought
I could still see the upper boundary of the Stronger Light, and that I could discern the lower edge of the
same at Antares ; but for the latter there was not sufficient space between the Milky Way and the horizon to
give me the direction. The whitish light along the horizon still continues ; and I have given, its boundaries
b b up to 7" 401", at which time it was merging itself into the Diffuse Light, and its limits were becoming
badly defined. Soon after, the whole Zodiacal Light was so dimly marked that I ceased to make observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
455
456 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 228.
DUPLICATE* OCTOBER 16th, 1854: MORNING.
Lat. at lh., 33° 16' N. : Lou. 177° 28' W.
Sun rose at 6A. 10m.
Stronger and Diffuse Light at OA. 30«- and l/i. Om.
Sun's Lon. 202° 48'.
Clouds and the nioou in the morning, since September 30th. Was on deck at llh 30'", but clouds were in the way.
About 15m after midnight the sky became clear, and was very bright and favorable; clear down to the horizon. The
Zodiacal Light could then be perceived, but it was very dim — only a faint tinging of the sky. The boundaries of
the Diffuse Light were better marked than those of the Stronger Light. By 1 o'clock the latter were more decided,
and were quite reliable. I could get no reliable boundaries above the Milky Way. The moon, now approaching the
horizon, began soon after to give additional brightness within the limits marked as those of the Stronger Light.
The moon showed itself on the horizon at lh 8"1.
•
* I have called this " Duplicate IB/A," because, although this is properly Tuesday, 17th, we drop a day, and call it Monday 16/A, as yesterday, in order to
have our reckoning on arriving at home, as we >-hall find it there. It is customary with our ships, when circumnavigating the globe, thus to rectify their time
on crossing the 18Uth degree of longitude from Greenwich, by dropping a day (calliog two days one), if going eastward, and by adding a day, if iu the opposite
direction.
BSERVATIONS ON THE ZODIACAL LKJHT.
457
458 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 229.
DUPLICATE OCTOBER Ifith, 1*54: EVENING.
Lat. at 7/i., 33° 01' N.: Lon. 174° 4!)' W.
Sun set at 5A. 21m.
Stronger and Diffuse Light at 7h. and 7A. 30m.
Sky perfectly clear, and very brilliant. I noticed that at 71' 10m the adjunct light under I b had the same warm
tint that the Zodiacal Light has — different from horizon or Milky-Way Light. At 71' 30"', the upper line of the
Stronger Light had evidently tilted up considerably, as given in the chart; the lower boundary could not be made
out at .this time ; also the boundary b l> had become less marked than before, this latter now becoming merged in the
Diffuse Litrbt. At 8h 30'" the boundaries of the Diffuse Light were about the same as a't the last observation.
OBSERVATIONS ON THK ZODIACAL LIGHT.
459
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OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 230.
OCTOBER 17th, 1854 : KVKKIKO.
Lat. at 7,'i. 31° 52' N. : Lon. 171° 28' W.
Sun set at 5/i. 22m.
Stronger Light i>.t GA. 55m, and 7A. 8m, i Diffuse at 7k. 10m.
Sky very bright. Going on deck at 6h 45m, I was struck with a remarkably bright appearance under the line a a.
It was rather late for twilight, but may have been such light ; but it was remarkably bright — as much so as the
Strongest Zodiacal Light ever is ; and it had the warm tinge of the Zodiacal Light. At 6h 50m, it had ascended to the
dotted line b b, and was extremely bright. Watching it, I thought it had pulsations in intensity. At 6h 55m it had
died away considerably in strength, and had ascended to c c ; Gh 57"', at c c, and its intensity as on previous nights ;
6h 58m, at c c, and brightness greatly increased ; 7'1 lm, c c, and dim again ; 7h 3m, do., and very dim. After this,
constant as at 71' 3m. At 71' 30m, clouds had overspread the sky, and I could get no further observations. Jupiter
makes useless any attempt at observations for the Stronger Light across the further side of the Milky Way.
OnSERVATIOXS ON THB ZODIACAL LIGHT.
462 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 231.
OCTOBER 18th, 1854: EVENISO.
Lat. at 7/i., 30° 41' N. : Lon. 167° 45' W.
Sun set at 5A. 22m.
Stronger Light at C/i. 50w. : Diffuse at 6A. 5i>ni.
Clouds till 6h 45mj when the western sky became clear and very brilliant, except along the horizon. Had an obser-
vation about 61' 50m. Soon after this, clouds overspread the sky ; they continued till morning.
OBSERVATIONS ON THE ZODIACAL LIGHT.
463
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464 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 232.
OCTOBER 20th, 1854 : MORHISO.
Lat. at 4/i., 23° 5' N. : Lon. 161° 24' W.
Sun rose at 6h. 7m.
Stronger Light at 4A. 15m. and 4A. 45m. : Diffuse at 4A. 15m.
Clouds in the morning ever since my last morning observation (ICth). Clouds also last evening. They con-
tinued until 4h this a. in., when the sky became beautifully clear and very brilliant. As usual, a far brighter spot
towards the horizon, both at 4h 15ra and 4h 25™, its upper boundary being the zigzag line. Dawn at 4b 50m.
OBSERVATIONS ON THE ZODIACAL LIGHT.
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466 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 233.
OCTOBER 21§t, 1854: MORNITC.
Lat. at 4A., 25° 58' N :Lon. 161° 58' W.
Sun rose £>h. 7m. f
Stronger Light at 4A , &c. : Diffuse at 4/(. 10m.
Clouds last evening, and also this morning, till towards 4h, when the sky became clear and was very brilliant.
When I went on deck, I was struck with the great brightness of the Zodiacal Light. I then had to change my
place from the poop-deck to the port-guard ; and though the time occupied by this was not more than two minutes,
I thought the brightness had very materially decreased. I watched, from that on, very carefully, to see whether
this was only a fancy, (though at that first observation I had not had any thought about pulsations,) or whether
there were really pulsations. Sometimes I thought there were, and I made the following records ; but I do not
offer them as reliable, it being exceedingly difficult to determine whether these apparent changes were true or not ;
and I had no one near, with whose judgment I could compare my own.
h. m.
At 3 52, very dim, and at a.
3 58, brightening.
3 59, much brighter, and at t>.
4 4, very bright, and at b.
h. m.
* *
4 14^, very bright, and at b.
4 15, greatly dimmed, and at a.
*
4 24, extremely bright.
The asterisks mean intervals when, although I thought it possible there were changes, I felt too uncertain to
make any record of them.
From the zigzag line down, the Light was much stronger than above, especially as dawn approached. The
Stronger Light, all the while, was so bright as to produce quite a decided discoloration of the smooth sea, as the
Light was reflected from it.
OBSERVATIONS ON TUB ZODIACAL LIGHT.
407
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4G8 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 234.
OCTOBER 21et, 1854: EVEMNO.
LaT. at ~h., 24° 49' N. : Lon. 160° 41' W.
Sun set 5A. 24™.
Stronger and Diffuse Light at fih. 50m.
Sky very bright. The ecliptic has now been lifted up so much by our getting further south, that I was able, this
evening, to get the lower boundary of the Stronger Light. This Light seems, also, now to project beyond the Milky
Way on the left ; but the effulgence of Jupiter prevents my getting its boundaries correctly. Clouds, after 1
o'clock, prevented further observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
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470 OBSERVATIONS ON TUB ZODIACAL LIGHT.
No. 235.
OCTOBER 23d, 1854: EVENING.
Lat. 21° 18' N. : Lon. 157° 55' W.
Sun set 5/(. 26£ m.
Stronger and Diffuse Light at 7 and 8 o'clock.
(22d was Sunday.) Clouds this morning. Sky, in the evening, clear and bright. Moon till about 7 o'clock, when
I got observations ; got boundaries above or on the left of the Milky Way, which I think may be reliable, though
Jupiter cast a strong light about that portion of the sky.
OBSERVATIONS ON THE ZODIACAL LIGHT.
471
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472 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 236.
OCTOBER 25th, 1854: MORNING,
Lat. 21° 18' N. : Lon. 157° 55' W.
Sun rose at 6A. 3m.
Stronger Light at 2A. 45m. aad 4A. : Diffuse at 4 o'clock.
Sky cloudy yesterday morning; moon now_in the evening. This a. m. was on deck at 1" SO"1; hut there was no
certainty of Zodiacal Light. Out again at 2'1 45m; sky very brilliant ; but there has been a great falling off in the
brightness of the early Zodiacal Light; got boundaries at that hour, but the Light was dim. At 4'1, however, it
was very bright — remarkably so.
OBSERVATIONS ON THE ZODIACAL LIGHT.
473
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474 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 237.
OCTOBER Sfltb, 1854: MORNING.
Lat. 21° 18' N. : Lon. 157° 55' W.
Sun rose 6/i. 6m .
Stronger Light at 2A. and 34. 45/«. : Diffuse 3A. 45™.
Clouds in the morning since last date. Moon in the evening. This morning the sky was very clear and bright;,
and I had good observations. At 2'' the Light was dim, though quite distinct ; at ray last observation, it was very
bright.
OBSERVATIONS ON THE ZODIACAL L1GUT.
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476 OBSERVATIONS ON THE ZODIACAL U01IT.
No. 238.
NOVEMBER 1st, 1854: MORMXO.
Lat, 21° 18' N. : Lon. 157° 55' W.
Sun rose at GA. 7m.
Stronger and Diffuse Light at 3A. 15;«. and 4/i. ]5;n.
Clouds yesterday morning. Went out this a. m. at 3", and found the Zodiacal Light distinct, though dim ; the
sky not at its brightest. Was able, however, to get boundaries. Out again at 4'1 15m, and found that the Light had
evidently slid over to the right very considerably. (See the chart.) The bounds of Diffuse Light rather difficult to
make out. The Stronger Light much the brightest below the zigzag line.
OBSERVATIONS ON TliK ZODIACAL LIGHT.
478 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 230.
NOVEMBER llth, ]«i-l: EVENING.
Lat. at 7/i. 20m., 23° 52' N. : Lon. 152° 34' W.
Sun set at 5A. 12m.
Stronger Light at 7/i. 15m. and lit. 35»i. : Diffuse at 7 o'clock.
Clouds or the moon since my last entry (November 1st). Had an observation this evening at 7" 15ra, but it was
unsatisfactory ; rendered so by flying clouds, and by the presence of Jupiter at the upper end of the Zodiacal Light.
This Light, however, was strong enough, at its lower end, to be distinctly seen crossing the Milky Way. At 7h 35™
the observation was more satisfactory, the clouds having disappeared, and the sky being very clear and bright. I
ihink the outlines of the Stronger Light, at this hour, may be considered reliable ; but I cannot speak positively
about those for the Diffuse Light ; this latter being imperfectly marked in the sky.
OBSERVATIONS O.N T1IK ZODIACAL LIGHT.
-179
480 OBSERVATIONS ON TUB ZODIACAL LIGUT.
No. 240.
NOVEMBER 13th, 1851 : EVESJNG,
Lat. at 7A., -2fi° 31' N. : Lon. 147° 27' W.
Sun set at 5 A. 74m.
Stronger and Diffuse Light at 7 o'clock.
The 12th was cloudy. Sky, this evening, clear and bright, except some flitting clouds towards the horizon. The
observations were, however, unsatisfactory. Jupiter above, and the Milky Way below, interfered.
OBSERVATIONS ON THE ZODIACAL LIGHT.
481
.J82 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 241.
NOVEMBER 20th, 1854 : MORNING
Lat. at 5A , 36° 1?' N. : Lou. l'2iij 51' W.
Sun rose at GA. 4(im.
Stronger Light at 4 ami 5 o'clock: Diffuse at 5 o'clock.
Clouds since last observation (13th) till yesterday, which was Sunday. Was on deck this a. m. at 4 o'clock, but
found the sky not very favorable ; some clouds in the east, and a slight haziness. The Zodiacal Light was dim, but
I was able, still, to have a pretty reliable observation. At 5" the sky was very bright and clear, and the Light very
brilliant, especially up as high as the zigzag line x. The Diffuse Light was so badly defined at its upper end, that
I was not able to carry its boundaries higher than as in the chart.
OBSERVATIONS ON THE ZODIACAL LIGHT.
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481 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 242.
NOVEMBER 2Cth, 1854: EVENING.
Lat. at~A., 36° 54' N. : Lon. 125° W.
Sun set at 4/i. 4'2/n.
Stronger and Diffuse Light at Gh. 3()m. and 7/i. 3()m.
Sky very clear and bright. The Zodiacal Light quite distinct at G" 30™, and the Diffuse Light also very well
defined. Jupiter is still troublesome, but not so much so as formerly.
OBSERVATIONS ON THE ZODIACAL LIGHT.
485
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486 OBSERVATIONS ON TUB ZODIACAL ALIGHT.
No. 243.
NOVEMBER 21st, 1854: MORNING.
L;if. at 4A., 37° 16' N. : Lon. 1^3° 33' W.
.Sun rose at 6A. SOjn.
Stronger and Diffuse Light at 4/i. 15m. ami SA. 15>«.
A very beautiful and clear morning. The Zodiacal Light very well defined at 4" 15"', and very bright and
strongly marked at 5'' 15m ; brightest up to the zigzag. I was desirous of watching for pulsations ; but I am quite
an invalid now, and was fearful of trusting myself too long in the cold morning air and the heavy dew then falling.
DISSERTATIONS ON THE ZODIACAL LIGHT.
<J87
488 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 244.
NOVEMBER 22d, 1854: ETENING.
Lat. 37° 48' N. : Lun. 122° 21' W.
Sun set at 4h. 40wi.
Stronger and Difif.ise Light at 6A. 50m.
Heavy fog last evening. The moon, this evening, did not set till about 6' 50'", when I was able to have a tolerably
satisfactory observation. A fog then rising rapidly, anil ob.scuring the western sky, was somewhat of a diawback,
inasmuch as I had to take the outlines hurriedly before it reached us ; but I believe they may be relied on. The
fog prevented any thing further through the night.
OBSERVATIONS ON THE ZODIACAL LIGHT.
489
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490 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 245.
NOVEMBER 25th, 1854: MORNING.
Lat. 3-° 2' N. : Lon. 1 22° 7' W.
Sun rose at 6/1. •'"!'".
Stronger and Diffuse Light ;it 4/'. 15m. and 5A. 15m.
Fog since last date in the morning. Moon in the evening. This a. rn. sky not very bright: the Zodiacal Light,
however, giving very good outlines. At 51' 15m it was somewhat dull ; brightest up to the zigzag.
OBSERVATIONS ON THE ZODIACAL LIGHT.
491
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492 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 246.
NOVEMBER 27th, 1854: MORKJNB.
Lat. 3-° v.' N. : Lon. 122° ?' W.
Sun rose at 6//. 58m.
Stronger and Diffuse Light at 4/i. 15m. and 5/f.-15m.
(Yesterday was Sunday.) The sky, at this place [Benicia, California], is perfect ; a clear deep Hue during the
day, and stars brilliant at night. The Zodiacal Light, at 4" 15°', was not bright, but had its outlines very well
defined. At 5" 15ra, very bright. At that hour I could not get the upper limit of the Diffuse Light, which was also
not very distinct at 4h 15m. I looked to see whether there were pulsations at 5" 15ra, the circumstances being so favor-
able for observing them, if there wore any ; but none could be perceived.
OBSERVATIONS ON THE ZODIACAL LIGHT.
493
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494 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 247.
NOVEMBER 28th, 1854: M-IRNINC..
Lat. 38° 2' N. : Lou. 12'2° 7' W.
Sun rose (V/. 59?».
Stronger and Diffuse Li^lit at :i and 5 o'clock.
Sky very brilliant. Rose at 3% and found the Zodiacal Light, though dim, yet quite distinct. The outlines were
not very well marked ; but I was still able to get them reliably. At 5h the Light was very bright, especially up to
the zigzag ; but I was not able to see any pulsations. The morning was remarkably favorable for observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
495
496 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 248.
NOVEMBER 29th, 1854: MORNING.
Lat. 33C 2' N. •- Lou. 122° 7' W.
Sun" rose at 7A. Jm
Stronger Light at 2A. and 4A. 30m. : Diffuse at 4A. 30m.
Moon set a few minutes before 2 o'clock. At 2" went on deck, and found the Zodiacal Light distinctly marked in
the sky, though it was difficult to get its outlines. Blowing violently ; hut sky perfectly clear and brilliant. At
y 30™ again on deck, but found the sky clouded over. At 4" 30™ it had cleared off again, except towards the horizon,
and I was able to get reliable boundaries, except for the upper end of the Diffuse Light. The upper end of the
Stronger is also now badly defined.
OBSERVATIONS ON THE ZODIACAL 'LIGHT.
497
498 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 249.
DECEMBER 7th, 18o4: EVENING.
*
Lat, 38° 2' N. : Lon. 1-22° 7' W.
Suu set at 4h. 35£rn.
Stronger Light at Gh. 30m. and 7/<. 15m. : Diffuse Gfi. 30nj.
Clouds since my last date (November 29th), until this evening. Sky, to-night, very hright and clear, and I had
a good observation at 6" SO1" : not so good at 7h 15m? as the moon, then, approaching the horizon, hurried me.
OBSERVATIONS ON THE ZODIACAL LIGHT.
499
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50 ' OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 250.
DECEMBER 8th, 1854 : EVENING.
Lat. 38° 2' N. : Lon. 122° 7' W.
Sun set at 4A. 36nt.
Stronger and Diffuse Light at GA. 30m. and TA. 30 HI.
Sky remarkably clear and brilliant, and extremely favorable for observations. At 6h 30m the 'outlines were all
well marked, except the upper end of the Diffuse Light. At 7'' 30'" the Stronger Light -was dim, but its boundaries
were still pretty easily made out.
OBSERVATIONS ON THE ZODIACAL LIGHT.
501
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502 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 251.
DECEMBER 9th, 1854 : EVENINS.
Lat. 38° 2' N. : Lon. 122° 7' \V.
Sun set at 4/i. 36™.
C 6h. 30m.
Stronger and Diffuse Light at < 7 30
t 8 0
Sky brilliant. The outlines of both Stronger and Diffuse Light were remarkably well marked at 6" 30m ; also, at
7" 30m, very distinct ; at 8h, dimmed considerably, but outline still good ; at 8h 30ra, Light still distinct : boundaries
not easily made out, but seemingly as at 8 o'clock.
OBSERVATIONS ON TilE ZODIACAL L1G11T.
503
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504 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 252.
DECEMBER IHh, 1854 (Kith was Sunday) :
Lat. 38° 2' N. : Lon. 122° 7' W.
Sun set at 4A. 36im.
Stronger and Diffuse Light at 6h. 15m. and Ik,
Sky clear and very brilliant. The Zodiacal Light quite distinct at C" 15"' : stronger at 71' ; at 7'1 30'", strong, and
outlines apparently the same as at 7h.
OBSERVATIONS ON THE ZODIACAL LIGHT.
50G OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 253.
DECEMBER 12th, 1854: EVEN-INS.
Lat. 38° 2' N. : Lon. 122° 7' W.
Sun net at 4A. 37 m.
Stronger and Dilfuse Light at
( 6/i. 15m.
? 7 15
( 8 10
Sky clear, and very fine for observations. At 6h 15m, boundaries very well marked. I was particularly careful
this evening with reference to the sliding over of the Stronger Light as the night advanced. The sky was very
favorable for nice observations. The result is in the chart. The query is: Is the spreading out of the southern or
left boundary owing to the Zodiacal Light now crossing the ecliptic? or is it owing to the position at which we view
the Light ? The fact that, as the night advances, the southern boundary slides so as to approach nearer to a parallel-
ism with the ecliptic, seems to give an affirmative answer to the latter of the above queries.
At 8" 1CP, the Light had dimmed, but was still bright ; and at 8" 21°', it still gave well marked boundaries, the
same as at 8h 10m.
OBSERVATION'S ON THK ZODIACAL Mill IT
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508 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 254.
DECEMBER !3th, 1854: EVENING.
Lat. 37° 46' N.: Lon. 122° 21' VV.
Sun set at 4/i. 33m.
( 6h. 15m. )
Stronger Light at? 7 15 > Diffuse Light at C^. 15m. and 7fi. 15m.
(8 (I S
Sky clear, and very brilliant. The Zodiacal Light quite bright at C'1 15°'. At 8'1 15m, dim, but distinctly
marked. Had some difficulty in getting outlines at that hour, but believe those in the chart may be relied on. The
Diffuse was about the same as at 7h 15'". At 9'1, the Light could still be made out, and its upper end had evidently
ascended up as high as 6 and 8 Pisciurn, but I could not get reliable boundaries. The night, at that hour, was still
very brilliant, and favorable for observations.
OBSERVATIONS
T\IK X/HMAn.vr, r.ir,HT.
509
<-
510 OBSERVATIONS ON THE ZODIACAL LIGHT.
X... 255.
DECEMBER 15th, J854: EVI-.NINO.
Lat. 37° 48' N. : Lon. 132° 21' \V.
Sim set at 4/i. 39m.
Stronger and Diffuse Light at 9/i. 20m.
Last evening too hazy for reliable results. So, also, at the early part of this evening.
I have for three or four nights past noticed what seemed to be a great ascent of the Zodiacal Light in the sky
towards 9 o'clock ; but the Light was so dim, and the appearance was so strange and unusual, that I was unwilling
to make any record of it, until further and more decisive observations ; so anxious am I to guard against optical
illusions. But this evening, the sky at 9h being particularly clear and favorable, this extended Light was so decided
that I could no longer hesitate. To make the matter more certain, however, I took the quartermaster on watch, and,
pointing out an extent of one quarter of the sky southward of the Milky Way, asked him to say whether he thought
any one part was brighter than the rest. He replied, " Oh yes, and I can tell you at once where it is ; for I have been
observing it several nights." He then gave the outlines as I have drawn them in the chart for the Diffuse Light,
except that he did not carry them higher than 71 Piscium, near where I have made the Stronger Light terminate. I
had no difficulty in making out the boundaries of both Diffuse and Stronger Light.
At 10h 3(P there was only a slight discoloration of the sky in that portion of it lying within the limits given at I)'1
20"', and no reliable boundaries could be drawn.
OBSKRVATIONS ON TUB ZODIACAL LIGHT.
511
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I
512 OBSERVATIONS ON THE ZODIACAL LIGHT,
NO. i!f>i;.
DECEMBER Kith, IH54: EVKMMG.
Lat. at 8A., 37° 21' N-: Lwi. U'^ 45' W.
Sim set at 4A. 40m.
( 6/1. 25m. 1
Stronger Light at < 7 3(J > Diffuse, 6A. 25m. and "h. '30m.
( y o )
Sim's Lon. 203° 15'.
The .sky, this evening, at 6'1 25m clear, but the stars not bright, and the time not the most favorable for observa-
tions. Had some difficulty in getting outlines. Dim still at T oO"'. At 9'1, 1 could perceive that the Stronger Light
had shot up, as noticed for some evenings previous (see last entry); but I was able to get only the upper boundary,
8ome clouds, rapidly ascending, having shut out the lower one.
OBSERVATIONS ON THE ZODIACAL LIGHT.
513
514 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 257.
DECEMBER 18th, 1854 : MORNING.
Lat. at 3A., 33° 58' N. : Lon. 120° 26' W.
Sun rose at ~/i.5m.
Stronger and Diffuse Light at 2/i. 15m. and 3^. 30m.
Sun's Lon. 266° 16'.
Clouds yesterday ; also on Sunday. Sky this morning very clear and brilliant above ; a few clouds near the
horizon. Was on deck at 2h 10'", and found the Zodiacal Light very distinct, with boundaries well defined. At 3"
30m the Light was not as strong as at 2h 15m, and the outlines were not so well marked, although the sky was as clear
and the stars as brilliant as at the previous observation. I could not tell what caused the difference. The Diffuse
was seemingly as at 2h 15m : its upper end at neither time clearly defined.
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f>16 OBSERVATIONS ON TUB ZODIACAL LIGHT
No. 258.
DECEMBER 18th, 1854 : EVENING.
Lat. at 8A., 31° 43' N. : Lon. 120° 3' W.
Sun set, 4h. 55m.
Stronger Light j gA- ^m' | Diffuse, 7k. 45m. and 8h. 30m.
Cloudy till near V 45m, when the sky became favorable for observations. I thought, this evening, that there were
probably pulsations ; and for a while made record of what seemed to be such : but all was so uncertain, that I feel
unwillrng to copy them, but concluded to wait for further observations. They seemed to have a and b for their
boundaries: and finally, at 8h I"1, the Light seemed to remain permanently at c — its boundaries permanent, but
pulsations in intensity still continuing. At 81' 30m it was still distinct, though dimmed considerably.
OBSERVATIONS <>N Tllli ZODIACAL LIGHT.
517
•
518 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 259.
DECEMBER 19th, Ie5-l. : MORNIN...
Lat. at 4h., 31° 5}' N. : Lon. 1 19° 23' W.
Sun rose at 6A. r>7«'.
( 2/i. dm.
Stronger and Diffuse Light/ 3 30
( 5 0
Sun's Lon. 2G7C 19'.
Sky, all morning, remarkably fine for observations. Was on deck at half an hour after midnight, and found the
eastern Zodiacal Light distinctly and unmistakably marked in the sky, though faint, and it was somewhat difficult to
get outlines. Thought also that, at that hour, I could trace a remnant of the same Light in the western sky ; but
it was not decided, and gave no reliable boundaries. At 2h the eastern Zodiacal Light was bright, and at 3h 30" quite
so. At 5h it was as brilliant as I have ever seen it, and was especially so within the zigzag, where this effulgent
Light had more of a cone shape than I ever saw it have before.
di:>i. I:\-.\TIU\S us Tin-: XODIACAI. IICIIT.
020
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 2GO.
DECEMBER 19th, 1854: EVKNING.
Lit. at 8A., 2D° 39' N. : Lin. 117^ 20' W.
Sun set 54. Urn.
Stronger Light, j f~ ^?m'' &c'' to j Diffuse, 6h. 30m. and 7A. 30m.
Sky very fine for observations. At 6'1 30'n the Zodiacal Light quite "bright, but with no apparent pulsations, though
At I'1 SO'" took b~>un laries again, marked b b, and then thought,
I made the following record :
7
*
h. m.
At 7 42,
7 44,
45,
4fi,
very bright,
dimmed somewhat,
bright,
very bright.
I watched carefully to see whether there were any.
but not confidently, that there were such changes.
k. m.
At 7 31, at a, and dim.
7 32, brightening.
7 334, tolerably bright, and at b.
7 34£ bright.
7 38, no change.
38£, very bright.
*, dimmed apparently ?
The asterisks mean an interval when no particular record was made.
I give this, however, with hesitation ; for the changes, if there were such, were very slight ; and I often suspected
that what I took to be such, are only the consequence of very intense watching and the imagination, or a change in
looking from the darkened part of the sky b.xck to the Zxliaeal Light. At other times I was more certain.
At 8" 451" the Light was at d ; was dim, but still very distinct and well marked. Tae sky very clear and brilliant
this evening.
7 48, at c.
7 54, seems to be permanent in brightness, and at c.
OBSERVATIONS ON Till: /.O|.I ACAl. I.HMIT.
52 J
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522 OBSERVATIONS ON THE ZODIACAL UGIIT.
No. 2G1.
DECEMBER 20th, 1854: MORXIV.;.
Lat. at 3A. 30m., 28° 50' N. : Lnn. 116° 43' \V.
Sun rose 6/». 54m.
Stronger and Diffuse Light, 3A. 30m.
Sun's Ion. 268° 20'.
Worn out by the watchings of the previous nights, I did not have myself waked this a. m. till 31' 30m, when I
found the sky not favorable for observations ; but I was able to get outlines, as in the chart. Clouds prevented my
getting the lower boundary of the Diffuse Light.
At 51' was out again, but the sky was now so dimmed by clouds that I could get no reliable boundaries.
OBSERVATIONS ON THE ZODIACAL LICHT.
523
66
52 1 OBSERVATIONS ON THE ZODIACAL LIGHT.
. -j <;•_'.
DECEMBER 20th, 1854 :
Lat. at 8h., 26° 51' N. : Lnn. 1 15° 27' \V.
Sun set at 5/i. ?wi.
*. 30m. )
Stronger Light at ? 7 3 t > Diffuse, G/i. 3()7«. and 7/i. 30;».
and midnight. )
Sun's Ion. 2(58° 20': Zenith point at midnight, Lat. 4° 45' N. : Lon. 89°.
( 6*
t ? 7
( an
At 6h 30™ the Zodiacal Light was very strong, but I could see no pulsations, though the night was favorable for
observations. Watched from 7" 20m to 7" 45m for pulsations, and thought, at times, that there were such changes ;
but all was so uncertain, that I feel linwilling to make further records of them. At 7" 45m the Light was still bright
and strong. Went out again at 9 o'clock, but found the sky all clouded over.
Was on deck again at midnight, and found the Zodiacal Light simultaneously in the E. and W. In both directions
I thought it was very decided, though faint; the eye easily discovered and recognized it, I have given its boundaries
in the chart. At 12'1 45m this western Light was still distinct.
(For both eastern and western Light, see morning chart — 21st.)
OBSERVATIONS ON" THK Z<>I>I. \r.\I, I.HIIIT
7- _-"
— •'
-
OBSERVATIONS ON THE ZODIACAL LIGHT
No. 263.
DECEMBER 21st, ]854: MORNING.
Lat. at 4h , 25° 5-' N. : Lon. 114° 48' W.
Sun rose at 6/1. 47«?.
( uitilnigh
t- ~l/t. I'm.
Stronger Light at- ~l/t. I'm. > Diffuse at 4 o'clock.
M 0 ^
Sun's Ion. 269 3 21'.
Was on deck at midnight, and found the Zodiacal Light over both west and east horizons distinct, and easily
made out at that hour. At that hour the ecliptic is now nearly perpendicular to the horizon. The sky at ]2h was
favoiable for observations; but at 2'1 I had to contend with parsing clou-Is, between which, however, I succeeded in
getting reliable boundaries. The same cause interfered at 3'1 30'", and I was n:>t successful in getting the full out
lines till 4 o'clock. On deck again at 5h, but found the sky so obscured by clouds, that no reliable results could be
procured.
Clouds prevented my bounding the Diffuse Light till 4\ I noticed that the effulgent Light, marked by the
zigzag, began to show itself about 4 o'clock.
YW tlir
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523 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 264.
DECEMBER 22d, 1854 : MORNINO.
Lat. at 4£.,23° 16' N. : Lon. 112° 30' W.
Sun rose at 6A. 41m.
Stronger and Diffuse Light at 3A. 30m. and 5A.
Clouds prevented observations last evening. The morning sky was very clear and brilliant, and I had good
observations. But the Diffuse Light is now so strong, and the Stronger Light melts so gradually into it, that it is
very difficult to get boundaries for the latter. At the first observation this a. m., I spent half an hour in verifying
my boundaries; and I believe those given may be relied on. Both then and at 5" I was particularly careful in my
observations. At 5" the effulgent Light within the zigzag lines was very brilliant. Watched to see whether there
were |nil^iti.>iis, but could not discover any. Could not get the upper end of Diffuse Light.
OliSKUVATIONS ON TI1K XnDIACAI. LIC.11T.
529
_
030 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 2G5.
DECEMBER 22d, ]854: EVENING.
Lat. at Sh., 21° 49' N. : Lon. 110° 39' W.
SUQ set at .")A. -Jllm.
Stronger and Dillusa Li^bt at 8/1. 3'lm.
The moon did not set till about 811 SO1", at which hour I was able to get an observation. The Zodiacal Light was
still distinct, though dim, and gave boundaries which I think may be considered reliable. I was on deck again
at midnight, in order to get east and west simultaneous observations ; but there was such a haziness over the
horizon as to defeat all such efforts.
OBSERVATIONS ON THE ZODIACAL I.IOHT.
531
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67
532 OBSERVATIONS ON THE ZODIACAL LIGH11.
No. 266.
DECEMBER 25th, 1854: MORNING.
Lat. at 4A., 17° 21' N. : Lon. 103° 17' W.
Sun rose at 6*. 32m.
( 12*. 30m. 1
Stronger Light at { 3 0 > Diffuse at 3*. and 4/i. 3f)m.
? 4 30 ^
Sun's Ion. 273° 26'.
Cloudy the last two mornings. I was on deck at 12 o'clock to-niglit, but was baffled by passing clouds till 12"
3CP. The sky then was free from clouds, but was not at its brightest ; yet I thought there could be no doubt of the
Zodiacal Light, at that hour, at both western and eastern horizons. The western gave roe boundaries more easily
than the eastern, where I had some difficulty in getting them satisfactorily. At 3" the sky was brilliant, and the
Zodiacal Light very bright ; but there was the same difficulty, as on the 22d, iu getting boundaries of the Stronger
Light, and from the same cause. At 4h 30'" the Light was remarkably strong ; strongest within the zigzag lines.
Dawn towards 5 o'clock.
.
534 OBSERVATIONS ON TUB ZODIACAL LIGHT.
No. 267.
DECEMBER 25th, 1854 : EVENING.
Lat. at 7/i. , 16= 31' N. : Lon. 101° 25' W.
Sun set at 5k. 30m.
Joint BUQ and muim at 6A. 30m. : Stronger Light at miduight.
Suu's Ion. 273° 2(i'.
Joint Sun and Moon Zodiacal Light, &c. — I have been on the watch, ever since my observation of March 6th, for a
joint sun and moon Zodiacal Light, but have not been successful until this evening, when the moon being in the right
position, and the sky remarkably clear and bright — clear down to the very horizon — I had a successful and a remark-
ably interesting observation. Going on deck as soon as the evening had sufficiently advanced — i. e., at 6h 501" — I
found the sky decidedly marked by a bright streak within the usual bounds of the Zodiacal Light. This had not
the ordinary warm coloring of the Zodiacal Light ; but was more like a dim silvery moonlight ; but of the greater
brightness itself, within these boundaries, there could be no doubt. I sent for Dr. - — , and asked him to tell me
whether he saw any particular brightness in that part of the sky ; which he did at once, giving it the boundaries
that I have given in the chart, except that he did not carry it so far up. Captain Lee and acting Lieutenant K ,
then on the poop-deck, also made it out without any difficulty. This observation is the more interesting and
remarkable from the fact that the Light, although deriving its strength, in a great degree, from the moon (to such
a degree as to make it surpass the surrounding moonlight itself), did not stretch up exactly in the direction of the
moon, but kept within the Zodiacal Light bounds, while the moon itself was quite outside of these. See the position
of the moon in the chart. This Light continued till *7h 48m as striking as at the first sight of it at 6" 50m. At 8"
it was not so strongly marked ; at that hour, however, it appeared to stretch up beyond the moon ; but of this last
I am not certain.
The night being so fine for observations, I determined to have observations of the simultaneous east and west
Zodiacal Light as early and as late as it would exhibit itself; to be made with particular care. The moon,
however, did not set till llh 36'", and its effulgence in the western sky continued for some time after. Immediately
on its setting, the eastern Zodiacal Light became manifest, quite decidedly showing itself; but its right-hand or
southern boundary was so uncertain, that I cannot give the one in the chart as fully reliable. The western Zodiacal
Light, when the moonlight was fully gone, showed itself also, I thought decidedly, and I got its boundaries without
difficulty. But neither in the east nor west was this Zodiacal Light so satisfactory or strong as on previous recent
occasions. The horizon, at midnight, has now changed considerably, owing to our rapid progress to the south, and
the ecliptic and it are no longer perpendicular, as before.
At 1 o'clock, in the west, there was nothing reliable. In the east, the Light had strengthened ; but I had the
same difficulties about its boundaries as before.
(The direction of this Light, at the observation of 7h 50m, may show that the moon exercised no sensible attrac-
tion in the substance producing it.)
P. S. December "26, Evening. — I looked this evening to see whether there might be a similar Zodiacal Light ; but there
was none. The moon had doubtless got beyond the proper position for such a result.
OBSERVATIONS ON TIIK ZODIACAL LIGHT.
535
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536 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 268.
DECEMBER 23th, Isl54: M.JKNING.
Lat. at 4A., 15° 59' N. : Lon. 10(1° 24' \V.
Sun rose at 6A. 3Uwi.
I HA. 45'«. of 25th. ~>
Stronger Light at -J „, u!^ ' > Diffuse 3A. tlm. aud 4A. '.'• .
U ' 30 " J
Sun's Ion. 274° 27'.
For a notice of a simultaneous east and west Zodiacal Light on this occasion, ste evening record of the
25th. As there stated, I found, when the moon set at 11" 3(in', the eastern Zodiacal Light decidedly marked on the
sky ; its northern boundary easily made out, but the southern one not to be procured so as to be fully reliable ; but
I have done the best I could. Wishing to make certainty more certain, that this was the Zodiacal Light, I watched
it till 12" 3CP, and was again on deck at 1 o'clock. At the latter hour it had increased in brightness, and had seem-
ingly the same boundaries as at 11" 45'" and at midnight ; but it presented the same difficulties about the southern
boundary. A good exhibition of this simultaneous e ist and west Light seems to require that the ecliptic
should be at right angles with the horizon on both sides. That was the case a few nights ago ; but our rapid move-
ment southward has changed the angle considerably ; and, to-night, I did not find the midnight Zodiacal Light as
bright or well defined as on those recent occasions. I was glad, however, to have the observation, as the sky was
remarkably favorable, and, owing to the increase of the moon, I can expect no more such for some time. At 3h and
4h 30°', the Light was remarkably bright: brightest at 4b 30"', below the zigzag.
•No. '238 >• ,
r£~ . •_, is}-
Midniht
538 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 269.
DECEMBER 2«th, 1854: MORHINO.
Lat. at 4A., 13= 18' N. : Lon. 94° 44' W.
Sun rose at 6A. '23m.
Stronger Light at 3A. Om. and 4/<. 30m. : Diffuse at 3 o'clock.
Son's Ion. 276° 29'.
Clouds yesterday morning. Sky this a. m., at 3 o'clock, very clear and bright ; at 4h 30™ was troubled by passing
clouds, but still, by careful watching, I was able to get reliable boundaries for the Stronger Light: could not succeed
for the Diffuse at that hour. The remarkable sliding over of the upper part of the Stronger Light, which may be
seen in all my recent observations, was so great this morning, that I could not be satisfied about it until after re-
peated trials, all bringing the same result. I believe that the boundaries on the chart may ba considered fully reli-
able, each new effort to trace them, by different stars, having given me the same result. The effulgent Light, very
strong at 4'1 307", is marked by the zigzag lines. Dawn at 5 o'clock.
!iV.\rii.NS ON Tllli /:<>UIACAf, LIGHT.
-_.
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510 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 270.
DECEMBER 29th, 1%4 : MORNING.
Lat. at 4/i., 11° 33' N.: Lon. 9i° 3' \V.
Sun rose at 6A. 2'i>».
Stronger and Difl'use Light at 3.';. aud \h. 30™.
Sky remarkably favorable for observations, both at 3'' an I at 4" SO"1. Took great pains to get the b militaries cor-
rectly, and I believe those given may be relietl on. though they are not very strongly rairkal at their U[>[>cr end;
and I had to make frequent trials before I could satisfy myself of my correctness. The upper end of the Diffuse Light
is so indistinct that I now make no effort at getting it.
OBSERVATIONS UN THK ZODIACAL LIGHT.
541
i
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542 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 271.
DECEMBER 30th, 1854: MORSIBG.
Lat. at 4A., 10° 46' N. : Lon. 89° 31' \V.
Sun rose at (ih. ~Zlm.
Stronger Light at 4A. lorn : Diffuse at 4/i. 20m.
The sky was cloudy at 3" ; but by 4 o'clock it bad clsarel off again, and was very favorable for observations. I
was again particularly exact in getting boundaries, on account of the great c!r.i:ige which his occurred in the angle
between the axis of the Zodiacal Light and the ecliptic. It will be observed from the chart, that the latter, in this
latitude, and at this time, is nearly at right angles with the horizon. I also, this morning, gave attention to the
stars as seen through the Zodiacal Light, and found, even to 4" o(T, when the effulgent Light below the zigzag lines
is very strong, that with the naked eye I could readily make out stars of the 6tli magnitude within the effulgent
Light; for instance, the group of stars just south of 38 Librre (shown by dots at a on the chart), and also a single
star of 6th magnitude between 33 and 48, and 49 of do. (see dots at b on the chart) ; also a line of four stars below ID
Libr;B, and ranging with /? Libne (see dots at c on the chart) ; the two northernmost of these last are of the
7th magnitude, yet I think the naked eye detected them, even within this effulgent Light ; but the last are
near its upper edge. All this shows the great transparency of the substance giving the Zodiacal Light. At 41' 41'",
this effulgent part, which hitherto had been a warm light of great brightness, almost suddenly became a cold
whitish light, at the same time sinking down and spreading at its base on either side. At 4'' 46m dawn
fully showed itself.
OB8KKVATIOKS ON THIi ZODIACAL LK.Il'i.
5 13
E -
F
t -
'
Ml OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 272.
JANUARY 1st, 135r> (Monday): MORSISG.
Lat. at 4A. 39m., 7° -27' N. : Lon. 85° 3J' W.
Sun rose at 6/1. 17 m.
Stronger and Diffuse Light at 4/'. 3')»i.
The moon did not set till near 4h 30'". Went on deck at that hour, an I to an 1 the sky very bright and favorable
for observations. Had not much difficulty in getting biuiliries, b:it \vi5 still very c ireful and exact about
them. Afterwards watched the dawnlight, as it cvnrunsj.l at the h>rizjn an. I crept rapidly upward. At 4"
3'J'" it may be said to have fairly shown itself in the sky.
OBSERVATIONS ON THE XDHACAI. I.IGIJT.
15
'
•
;
• -•
-
i
_:
51C OBSERVATIONS ON THE ZODIACAL LIGHT.
No 273.
JANUARY 5th, 1855 : EVENING.
Lat. 8° 47' N. : Lon. 79° 31' W.
Sun set at 5^. 51.\m.
Stronger Light at "A. and "lit. 5Uw. : Diffuse at 7 o'clock.
Moon, and clouds also, since ray last, both morning and evening. This evening the western sky was clear
and favorable for observations. The Zodiacal Light was quite distinct at G1' 50'", but did not give fully reliable
boundaries till 7 o'clock. At 7" 50'" there was a singular appearance within the boundaries marked for that
time. It was as if a thin white gauze had been drawn along the sky, quite concealing the smaller stars, and
yet in all other respects like the Zodiacal Light. I thought, at first, it was a thin cloud or haziness, and
watched to see it change; but it \va< p.-nuauent, and, except its hiding the stars, was so much more like the
usual Zodiacal Light, that at last I recorded it as such. The Light at 7" was very strong, with a more efful-
gent portion below the zigzag line. Moon rose about 8 o'clock.
\TIil\S 0V Till! /.nni \C\1. IJCIIT.
517
518 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 274.
JANUARY 6th, 1855 : EVENING.
Lat. 8° 47' N: Lon. 79° 31' W.
Sun set at 5A. 51^m.
Stronger and Diffuse Light at 7 and 8 o'clock.
Sky favorable, very bright and clear. Zodiacal Light, at 7", very brilliant. The effulgent Light within the
zigzag lines lasted till 7" 40m : at 8", a little of it was left, but much dimmed. Looked for pulsations, but could
not see any. At 8" it was difficult to get the southern outline of the Stronger Light. Could not see any of
the gauze-like appearance dimming the stars, which was noticed last evening.
ON T11K ZODIA-'AI, I.KII1T.
5J9
fill
550 OBSERVATIONS ON TllE ZODIACAL LIGHT
No. 275
JANUARY 8tli, 1855: EVENING.
Lat. 6° 47'N. : L.m. 79° 31' W.
Sun set at b/i. 'rim.
Stronger Ligbt at/"' ™m- &c'" to } Diffuse at 71,. 15w., &c.
SUB'S Ion. 287° 42'.
Yesterday was Sunday. Clouds in west, this evening, till after 7h, when the sky cleared off, and became extremely
favorable for observations. It will be seen by reference to the chart, that the ecliptic is, at that hour, nearly perpen-
dicular to the horizon. At 7' 15" the effulgent Light bslow the zigzag was remarkably bright. I took the boundaries
as in the chart, but in fifteen minutes after was surprised to find that already they were considerably extended; and
I began to query whether there were not pulsations. At 7" 3(Jin I was satisfied that there were ; for the Light was
now back at the first boundary a a, and had dimmed considerably. My record from this was as follows:
h. m. /*• m.
"At 7 39, brightening.
7 42, at b, and bright ; has brightened most deci-
ledly since 7" 39ra.
•<
7 50, decide-illy dimmed, compared with 7'1 42m.
7 52, has brightened and dimmed again in the last
2 minutes.
At 7 54, has brightened and dimmed once more since
last.
7 55|, bright, and at b.
7 58|, still bright.
8 o'clock, still so.
At 8" 8ra still bright, and its boundaries at c. A change has come over it in the last eight or ten minutes. It has
extended its boundaries to c c, and the upper part has become decidedly brighter than at any time before. In the
early part of the evening, say at 7" 15m, the portion below the zigzag was extremely bright; while the upper was
dimmed off, till it was very difficult to make out its highest portions. Now, the lower part is not strikingly bright;
while the upper portions, as just remarked, have increas'.-d in brightness, so that it is easy to trace them. This has
been since the pulsations ceased." I neglected to notice when the great effulgence below ceased. At 8h 30m boundaries
still well marked. At 10h 30m, perhaps a paleness in that part of the sky, but nothing decisive. In noticing these
pulsations, I was assisted by one of the petty officers of the ship : he had no difficulty in observing the changes of
the brightness.
OBSERVATIONS ON THE ZODIACAL LIGHT.
551
652 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 276.
JANUARY 9th, 1855: EVENING,
Lat. 8° 47' N. : Lon. 79° 31' W.
Sun set at 5h. 52m,
C 7/i. 20m. )
Stronger Light aU 8 0 > Diffuse at 7/t. 20m. and 8/;< Om,
( 8 10 )
Clouds obscured the western sky till 7" 15m : I was able, however, to notice that the effulgent Light under the
zigzag showed itself first at 7h 13m. Grot outlines at 7' 20"' ; but clouds still interfering, prevented ray having any
very satisfactory observations about pulsations, though I could see that there were such. My records say, " 7h 43™
exceeding bright : 7" 45m dim : 7" 53m very bright : 7" oo^"1 has dimmed sensibly : 7" 57™ brightening :" * * * 8
o'clock, now very bright. At S1' 5m the increased brightness at the upper part almost suddenly commenced ; the
effulgence below the zigzag still continuing, but not as bright as before." At 8h 10°" the southern or left-hand
boundary seemed to have suddenly extended to a a, as in the chart. At 8'1 15m the effulgence below the zigzag wag
gone. At 9h the Zodiacal Light was still strongly marked, but gave no reliable boundaries ; so also at 9" 45'°.
miSKKVATIONS ON TIIK ZODIACAL LKJ1IT.
553
-=^ --
;=• =
^=a
n
&54
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 277.
JANUARY 10th. 1855: EVENINO.
Stronger Light at{ "
Lat. 8° 47' N. : Lon. 79° 31' W.
Sun set at 5A. 53m.
11., &c., to
Diffuse at 7h. 15m. and 8A. Om.
Sky very brilliant, and everything favorable for observations,
record :
Thought I saw pulsations, and made the following
h. m.
* * *
'At 7 25, very bright, and at b.
7 27, dimming, at a.
7 28, dim do.
7 31, brightened.
7 32, bright, at I.
7 33, decidedly dimmed, at a.
(The dimming seems more rapid than the brightening.)
7 35, dim yet, and at a.
7 36, brightening.
7 37, bright, and at b.
7 38, quite bright, do.
7 40, still so.
7 41, do.
7 42, very bright now.
7 44^, still bright, and at b.
7 46, very bright, do.
7 48, dimmed somewhat.
(There seemed now to be slight pulsations in bright-
ness, while the boundary continued permanent at b.)
h. m.
At 7 50, brightened.
7 51, quite bright.
7 54, still bright.
57, do.
0, considerably dimmed.
5, brightened once more.
6, quite bright.
7, the upper part of the Zodiacal Light is now much
brighter than before, and the lower part is
dimmed.
8 10, lower part brightened again.
8 12, still so.
8 17 ; it seems tobs permanent as at last — bright be-
low, and tapering off; brightness very gradual
to the upper end ; the boundary as in the
chart at 8."
7
8
8
8
8
At 9 o'clock the Zodiacal Light was still very distinct, and with boundaries evidently much extended (so also last
night) ; but so dim, that it was difficult to get them reliably : but I made the attempt.
OBSERVATIONS ON THE ZODIACAL LIGHT.
556
556
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 278.
JANUARY llth, 185.r>: Evtiunfi.
Lat. 8° 47' N. : Lon. 79° 31' \V.
Sim set at 5/i. 54m.
7A. 15m., &c., to (
Stronger Light at <
Stars remarkably brilliant in a sky almost black; night extremely favorable for observations. At 7" 15'" the
effulgence below the zigzag very strong. Watched for pulsations ; sometimes doubted whether there were any at all ;
sometimes was certain that there were. My notes at the time were as follows :
"At 7 24,
7 26,
34,
7 28,
7 30^
7 32,
7
7
7
7
7
7
7
36,
37,
37!
39,
40,
741,
at b, and bright.
exceedingly bright.
still do.
, has just dimmed decidedly, and at a.
bright, and at ?>.
very bright.
, dimming.
evidently dimmed.
quite dim, and at a.
, brightening.
bright, and at b.
quite bright.
very bright.
42,
43,
44,
7 45,
7 id.
do.
still so,
do.
do.
do.
and no mistake about it.
h. in.
* # #
At 7 49, now quite bright. There seem still to be pul-
sations ; but they are so badly marked now,
that I cannot catch their periods.
7 50, very bright. The effulgence below the zigzag
now much dimmer than at first.
755, the light has almost suddenly extended to c.
7 57, dimmed once more.
7 58, quite dim.
7 59, has brightened.
0, has brightened considerably.
1, quite bright.
2, do. do.
5, still very bright.
8
8
8
8
8
8
7, do. do., seems now to be permanent.
10, still the same."
At 9 o'clock Zodiacal Light still well marked, and gave
reliable boundaries.
OBSERVATIONS ON THE ZODIACAL LIGHT.
557
558
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 279.
JANUARY 12th, 1855: EVENING.
Lat at 8k., 7° 7' N. : Lon. 79° 26' W.
Sun set at 5A. 57Am.
Strouger Light at lit. 20m , &c. : Diffuse 7A. 30m. and 8A. 20;«.
Sky very fine for observations. Through want of care, I was a little later on deck than I ought to have
been. The following is my record for the evening :
h. m.
'At 7 25,
7 29,
7 31,
32,
34,
36,
ohr
o7,
38,
35,
41,
7 42,
7 43,
44,
45,
46,
7 47,
48,
bright, and at b.
dim, and at a.
bright, and at b.
very bright, do.
dim, and at a.
still so.
very bright, and at b.
still so.
dim, decidedly, and at a.
brightening,
bright,
still so.
(I notice, this evening, a decided difference
in the boundaries on the right or north-
ward, between the Light when bright
and when dim.)
still as at last.
, very bright., at b.
do. do.
dim, and at a.
do. do.
bright, and at b.
, still so.
50, very bright, do.
h. m.
At 7 51, strikingly so, and at b.
do.
52,
7 53i,
7 54i, dimmed. f
7 56^, brightening.
7 57A, bright, and at b.
8 0, the boundaries called b have been gradually
extending beyond that, and have now got
to c. The zigzag has also just now as-
cended from x to y.
3, as at last, quite bright.
Still SO.
(i there seem to be pulsations in brightness,
\ but not in boundaries.
8 10, dimmed, and boundaries not as distinct as
before.
8 12, same as last.
8 13i, has just brightened considerably.
8 16, still as at last.
8 20, do. do. seems to be permanent at this.
9 0, the Zodiacal Light still decidedly marked in
the sky, but gives no reliable boundaries."
It may be well to repeat here, that, in these annotations about fluctuations, "do." means continued still at the same place,
t Passed Midshipman B was with me at this change, and remarked upon it at once, even before I had noticed it
OBSERVATIONS ON THE ZODIACAL LIGHT.
559
•I
if
560 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 280.
JANUARY 15th, 1855: EVESINO.
Lat. at 8h., 21' N. : Lon. 811° 37' W.
Sun set at 6/1. 9m.
Stronger Light at 7/i. 15;n. to t)A. : Diffuse at7A. 3ll)».
Clouds since the 12th. Sky this evening not in the best condition for observations ; somewhat hazy, and
troubled, also, by passing clouds. I did the best I could, and got boundaries, which are remarkable for their
great divergence from the ecliptic on the southern side. These boundaries were very carefully taken ; but I do
not consider them fully reliable : must wait to get others hereafter ; still, however, these outlines appeared to
be fairly marked in the sky. The effulgence within the zigzag was wonderfully great this evening ; the Diffuse
Light was not well defined. There were evidently pulsations, but the clouds prevented my making record of
them. The Light at 9h was dim, and its boundaries were very badly marked.
OBSERVATIONS ON THE ZODIACAL LIGHT.
561
:*•--£
----^g
a 3
B
562 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 281.
JANUARY 17th. 1855: EVKM:.T,.
Lat. at 8A., Z° 54' S : Lon. 81° 5:r \V.
Sun set at 6A. 14m.
Stronger Light at Ik. 3!lm. and 8A. 10m. : Diffuse at 7k. 30»;.
Clouds all last night ; also this evening, till half-past 7, when I was able to get an observation. It was
ont a very satisfactory one, however, as there still were clouds along the horizon ; and I could get boundaries
only towards the upper part of the Zodiacal Light ; and, even there, the sky was not favorable, on account of
a general dimness or slight haziness. There seemed to be pulsations, but the region of them was troubled by
the clouds, and I did not attempt to record them. At 8'1 10m, sky still the same. Soon afterwards it was quite
clouded over.
OBSERVATIONS ON THE ZODIACAL I.lGUT.
71
6G4 OHSKRV \T10NS ON THE ZODIAC A I, MORT.
No. 282.
JANUARY 18th, 1855: MORHINO.
Lat. at 4A., 3° 40' S. : LCD. 82° 20' W.
Sun rose at 6A. 4£w.
Stronger Light at 3A. 45m. and 4li. 30m. : Diffuse at 4 o'clock.
Was on deck at 3 o'clock. The Zodiacal Light was then very distinct, but I was prevented from getting
outlines by passing clouds till 3h 45m. After 4 o'clock, the sky was remarkably fine for observations, and I
continued making them with the greatest care. My notes are thus : " 4h 5m, the Zodiacal Light has just bright-
ened up considerably, more especially below the zigzag line w ; 4'1 20'", now a great effulgence within the zigzag
x, very marked in strength and in its boundaries ; 4h 25™, the whole Zodiacal Light very bright, but the marked
effulgence within x still continues ; 4h 50m, this extreme effulgence lias now sunk to the boundary y, and is very
striking : its bounds well marked ; 4h 54™, the Light is spreading laterally — doubtless the beginning of dawn ;
4h 56"', dawn has decidedly come."
At 4h 20m, noticed that the stars of the fifth magnitude, about 42 in the left foot of Ophiuchus, also 40 of same,
were very distinct, though in the middle of this effulgence.
OBSERVATIONS ON THE ZODIACAL LIGIIT.
565
660
OBSERVATIONS ON THK ZOIMACAL LIGHT,
No. '283.
JANUARY ISth, 1855: EVENING,
Lat. at Sh., 5° 7' S. : L»n. 82° 14' VV.
Sun set at 6/j. 18i«.
Stronger Light at 7A. 2()m., &c., to !IA. : Diffuse 7/i. 4u/«. au'l 8A,
when the Zodiacal Light was bounded as in the chart at « a.
A remarkably fine, clear night, and everything very favorable for observations. Began, to record them at 71' IS01,
My record is thus :
h. m.
At 7 47^, exceedingly bright, and at c.
7 50|, still so. The effulgence has ascended to z.
7 52, do. do.
7 54|, effulgence very great ; bounds at c.
(The effulgencejnot greater than at first, when
it readied only to x ; but it is now more
striking, inasmuch as it ascends higher up
to z.)
h. m.
"At 7 25,
7 26,
7 27,
7 27i
7 29,
7 31,
7 33,
7 33i
7
7
*7 3fil
I OU|
7 37,
7 38,
36,
7 40,
7 41,
7 42,
7 43,
7
7 47,
boundaries at a, and bright within the zigzag.
the brightness has extended to the zigzag y ;
boundaries at b.
at x, and dim.
, quite dim.
brightening.
bright, and bounded by b b.
still so.
, very bright,
, dimming,
brightening.
, bright, and at b,
quite bright,
still so.
, dimming.
dim, and at a.
brightening,
bright, and at b.
very bright, do.
, remarkably bright, and bounds have extended
to c.
still so.
7 56J, has just brightened somewhat.
7 58, dimmed a little, but bounds at c.
7 ">!), brightening.
8 0, bright once more. (How fast and
how strik-
ingly the angle of inclination with the
horizon changes !)
8 4, is quite bright, and extends now beyond c c.
8 9, bounds at d d ; but it is not so bright as before,
nor are the boundaries so well defined.
8 13, pulsations appear to have ceased : the Light
much diminished in strength.
'J 0, the Light distinct, but very dim, and its bound-
aries can scarcely be got reliably."
OBSERVATIONS ON THE ZODIACAL LIGHT.
60Y
568 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 284
JANUARY 10th, 1855: Monmxo.
Lat. at 4h., 5° 57' S. :Lon. 81° 52' W.
Sun rose at HA 2m.
Stronger and Diffuse Light at 3A. and 4A. 30m.
Was'on deck at 3 o'clock. Found the sky only tolerably favorable ; not very bright, and clouds also passing.
The boundaries easily got on the northern side, where they were well marked, and the change from, the Zodiacal Light
brightness to the darker sky is sudden and well defined ; but, on the southern side, the change is scarcely perceptible,
the sky beyond the boundaries still keeping a considerable degree of brightness. On that account, I could not get
the boundaries of the Diffuse Light on the southern side. (A very heavy dew falls now at night.) At 4" 3CT1, the
atmosphere dim. The Zodiacal Light was bright up to the zigzag x, but not at its brightest. Very difficult still
to get reliable boundaries on the southern side. At 4h 35m, up to x, brightening ; 4" 40m, do. do. ; but clouds near
the horizon and the dimness of the sky discouraged me from further efforts at observations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
569
|B
-- -
570 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 285.
JANUARY 20th, 1855: EVENING.
Lat. at 8A., 9° 52' S. : Lon. 80° 33' W.
Sun set at 6h. 26m.
Stronger Light at 8A. 45ni. and 9A. 15m. : Diffuse at Sh. 45m.
Clouds last evening and this morning. Moon did not set, this evening, till 8h 45™, when the night became very
favorable, being clear and bright. The effulgent portion, as bounded by the zigzag, was still worthy of note ;
and, at 9 o'clock, though greatly dimmed, it could be distinguished from the other portions. At 101' the Zodiacal
Light still continued ; the boundaries apparently as at 9'1 15'". It was now, however, very faint.
OBSERVATIONS ON THE ZODIACAL LIGHT.
r>n
572 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 286.
JANUARY 22d, 1855: MORNING.
Lat. at 4A., 12° 46' S. : Lon. 79° 23' W.
Sun rose at oh, 53m.
C '2/>. Om. 1
Stronger Light at? 3 0 > Diffuse at 3A. and 4/i. 30m.
( 4 30 )
21st was Sunday. Was on deck at 1" 45m, and found the Zodiacal Light very distinct and well marked ; passing
clouds prevented my getting houndaries till 2 o'clock, at which time the sky was extremely favorable : so it con-
tinued till daybreak. At 2h there was already a more effulgent part, which I have marked by the zigzag w. At 3''
the effulgence was down to x, and'was very strong ; sky remarkably fine for observations. No dew. On deck
again at 4" 15m, and now had some difficulty in making out the southern boundaries of the Stronger Light, which
I had not experienced before. The Light there passed off almost insensibly into the Diffuse Light. Still, I was
able to get what I think are reliable results. At 4" 20™ the boundary of the effulgent part had got down to y, and
the effulgence was less brilliant; "5" 35m, the light is spreading, giving signs of dawn; spreads fastest on the
southern side ; 4h 40m, dawn has come." At 4" 40m there were still faint traces of the Zodiacal Light at its upper
end, dawn not having reached there yet.
OBSERVATIONS ON THE ZODIACAL LIGHT.
573
574 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 287.
JANUARY 23d, 1855:
Lat. at 4k., 14° 44' 8. : Lon. 78° 51' W.
Sun rose at 5/i. 51»i.
Stronger and Diffuse Light at 2h. 30m. and 4/i. 30m..
Was on deck at 2" 30ra; sky very clear and bright. Had some difficulty in getting boundaries of the Diffuse
on the south, as they are not well marked. The Light was strongest of all below the zigzag x. At 4" 20"' the
effulgence extended only to y ; but it was very brilliant. Sky still very good for observations; but being very
unwell, I did not continue them further.
OHSERVAT10MS ON THE ZODIACAL UGHT.
,075
670 OBSERVATIONS ON THE ZODIACAL LIGUT.
No. 288.
JANUARY 30th, 1855: MORNIKO.
Lat. at 4A., 29 J 7' S. : Lon. 72° 49' W.
Sun rose at 5A. 32^'".
Stronger Light at 3 and 4 o'clo ck : Diffuse at 3 o'clock^
Clouds in the morning, moon and clouds in the evening, ever since my last date (23d). The moon set this morn-
ing just before 3h, after which I was able to get observations as in the chart. Morning very clear and bright,
blowing almost a gale ; heavy dew. The Zodiacal Light very dim at 3 o'clock ; and, at 4'', not as bright as
formerly. The effulgence beneath the zigzag was strongly marked. Dawn at 4h 8m.
OBSERVATIONS ON THE ZODIACAL LIGHT.
f,77
678 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 289.
FEBRUARY 6lh, 1855: EVENING.
Lat. 33° 1' S. : Lon. 71° 41' W.
Sun set at 6A. 56'«.
Stronger Light at 8*. 30m. and 9A. 15m. : Diffuse at 8h. Zfim.
Zenith point at 8A. 30m., Lat. 56° 29' S. : Lon. 82° 30'. At 9h. 15m., Lat. 56° 29' S. : Lon. 97° 30'.
Clouds (and the moon in the morning) since my last date (February 3d) until this evening, when the sky was clear,
and, except a slight haziness, was good for observations. The ecliptic' is, however, so near the horizon in the
evening, that the Zodiacal Light is by no means brilliant. Still I was able, by very careful observation, to get what
I consider reliable boundaries. The twilight is now very protracted, which adds to the dimness of the Light. At
9h 151" it was quite dim, yet distinctly to be made out.
OBSERVATIONS ON THE ZODIACAL LIGHT.
i
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1
l
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f)80 OBSERVATIONS OH THE ZODIACAL LIGHT.
No. 290.
FEBRUARY 7th, 1855: EVENING.
Lat. 33° 1'S. : Lon. 71° 41' W.
Sun set 6A. 55m.
Stronger and Diffuse Light at 8h. 20m. and 9A. 15m.
Zenith point at 8A. 20m., Lat. 56° 29' S. : Lon. 80°. At 9h. 15m., Lat. 56° 29' S. : Lon. 100°.
The night clear and very fine for observations. The twilight is very long, hut at 81' 10™ I could easily make out
the Zodiacal Light ; however, could not get reliable boundaries till 8" 20m. At 9h 15m the Light was dim, hut still
was easily distinguished and well marked. At that 'hour I could not get the lower boundary of the Diffuse Light.
At 10" I could see a slight tinge in that part of the sky, evidently the Zodiacal Light ; but I could not get bounda-
ries ; and, in fact, it was only a slight, faintly marked blush in the sky.
OBSERVATIONS ON TUB ZODIACAL LiCUT.
581
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-
-
•
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- :
-
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13
582 OBSERVATIONS ON THE ZODIACAL LIGHT.
FEBRUARY 8th, 1855: ETENJN. .
Lat. 33° 1' S. : Lou. 71° 4]' W.
Sun set at 6A. 54i>«.
Stronger and Diffuse Light at 8A. 15m. and 9A, 15m.
Zenith point at 8A. lorn., Lat. 56° 29' S. : Lon. 79°: At OA. 15m., Lat. 56° 29' S. : Lon. 101°.
Sky clear, and remarkably fine for observations. The Zodiacal Light was dim, but gave reliable boundaries, both
at 8" 15'" and 9h 15m : at the latter hour, however, it is somewhat difficult to make them out.
OBSERVATIONS ON THE ZODIACAL LIGHT.
583
684 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 292.
FEBRUARY 9th, 1855: EVEKISG,
Lat. 33° 1'S. : Lon. 71° 41' W.
Sun set at 6/». 53Jm.
Stronger and Diffuse Light at S/i. 15m. and Q/t. 15m.
Zenith point at 8/1. 15m., Lat. 56° 29' S. : Lon. 80° : At 9ft. 15m., Lat. 56° 29' S. : Lon. 103°.
Sky clear, and very favorable. It seemed to me that there were changes in the intensity of the Light ; lor,
sometimes, it was very difficult to make out the boundaries ; at others, they were tolerably plain. At 9" 15m,
however, the Light was very dim. I took boundaries this night again of the stretch of light a a, parallel to the
horizon, although I consider it only atmospheric light.
OBSERVATIONS ON THE ZODIACAL LIGHT.
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580) OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 293.
FEBRUARY 12th, 1855: EVENING.
Lat. at 8/1., 35° 41' S. : Lou. 73° 59' W.
Sun set at GA. 53^m.
Stronger and Diffuse Light at 8h. 45m.
Zenith point at 6A. 15'«., Lat. 56° 29' S. : Lon. 83°.
Clouds, since my last date, have prevented observations until this evening, when, at 81' 15m, I was able to have
one; the sky favorable above, but with passing clouds below. I thought that the lower or right-hand boundary <>!'
the Stronger Light, which was well defined, had evidently slid over towards the left, since my last observation. The
other boundary was not so decidedly marked in the sky, but it also appeared to have moved on, as may be seen by a
comparison of the charts. The lower boundary of the Diffuse could not be got, owing to clouds. After this obser-
vation, the sky was clouded over.
OBSERVATIONS ON THE ZODIACAL I.IGUT.
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588 -OBSERVATIONS ON THE ZOOIAHAL LIGHT.
No. 294.
FEBRUARY 19th, 1855: EVENING.
Lat. at 8A. 45m , 51° 57' S. : Lon. 75° 58' W.
Sun set at 7A. 14m.
Stronger and Diffuse Light at 8fi. 45m.
Zenith point at 8h. 45m., Lat. 74° 50' S. : Lon. 113°.
Clouds, ever since the last date, till this evening. The twilight now continues till a little after S" 30m, and hy that
time the ecliptic has got to he so near the horizon that the evening Zodiacal Light is of a very douhtful nature.
The sky this evening was very clear, the stars shining with an intense brilliancy ; hut, although I tried very hard to
see whether anything reliable could be made out, I found nothing satisfactory. On the chart are the boundaries of
what seemed to me to be something like Zodiacal Light ; but I cannot consider those of the Stronger Light to be at
all reliable. That of the Diffuse is more certain : its. lower boundary was not to be seen. The difficulty was,
perhaps, increased by a very strong light in the southern sky, rising far above the horizon — probably the blink of ice
about the southern pole. The air this evening was very sharp. At midnight the sky was still clear, and the stars
were bright to a degree that I never saw before. At 2", rose to get a morning Zodiacal Light observation ; but
before I could determine any thing about it, clouds swept over the sky : so they remained.
OBSERVATIONS ON THE ZODIACAL LIGHT.
589
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 295.
FEBRUARY 2 1st, 1855: EVENIKO.
Lat. 53° 33' S. : Lon. 70° 53' \V. : Port Famine, Straits of Magellan.
Sun set at Hi. 12 ».
Stronger and Diffuse Light at 9/i. anil 9/i. 30,n.
Zenith point at 9A., Lat. 74° 25' K. : Lon, 13(i° 3(1'. At 9A. Slim., Lat. 73° 30' S. : Lon. 142° 30'.
Clouds last night. The sky this evening was perfectly clear, and very favorable for observations ; but the twilight in
now very long (lasting till near 9 o'clock), and the ecliptic has now got down so near the horizon, even at its highest
part, that it is very difficult to get boundaries of the Zodiacal Light that can be called reliable. Those of the Diffuse
Light I think may be depended on. For the Stronger Light, I cannot speak so confidently ; but it was easily
seen, at 9 o'clock, that the Stronger Light near the horizon, on the left of Saturn, was quite wanting on the right
of that planet,* and the difference could be ascribed only to the Zodiacal Light. Dr. - - happened to be near me
at the time, and readily saw this difference as well as myself. At 9" S"1 it was better marked ; and at 9" 30m, the
night having deepened, I thought the Stronger Light more decided and more easily defined than at 9h, and I think
the boundary for that time may be considered reliable.
The southern glare (ice-blink ?) this evening was very striking.
0 Saturn had then a latitude oi about 1° 20' S., and Lon. of about C8° 30'.
OBSERVATIONS ON THE ZODIACAL LIGHT.
61)1
592 OBSEliVATlONS ON THE ZODIACAL LIGHT,
No. 296.
FEBRUARY 22d, 1855: MORNING.
Lat. 53° 35' S. : Lnn. 70° 53' W.
Sun rose at !ili. lUwi.
Stronger and Diffuse Light at 2/i. 3il«i.
Was on deck at 2 o'clock, and found the sky very favorable for observations. The Stronger Light was very
bright below the Milky Way, but very dim above it ; and it was very difficult to make out that portion of its bound-
aries. I could not get the lower boundary of the Diffuse Light at all ; and the upper one was very indistinctly
marked. Immediately after 2h 30'", a cloud began to cover the lower part of the sky ; soon afterwards it put an end
to observations. As my work had to be done rapidly, and the cloud prevented all attempts at verification, I cannot
speak of the boundaries, as I got them, with the fullest confidence ; but think they may be considered reliable.
Dawn commenced towards 3 o'clock. Thought that there were pulsations, both in boundaries and in intensity of
light, but could not be certain about it,
OBSERVATIONS ON THE ZODIACAL LIGHT.
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5<M OBSERVATIONS OH THE ZODIACAL LIGHT.
No. 297.
FEBRUARY 23d, 1855 : MORNIKO.
Lat. at 2*. 30m., 5-2° 28' S. : Lon. 67° 29' W.
Sun rose at 5A. 21m.
Stronger and Diffuse Light at 2fi. 30m.
Was on deck at 2h 20ra, and found the sky perfectly clear and stars very bright, and had a very satisfactory
observation. The Stronger Light was very well marked below the Milky Way, and sufficiently so above ; while, at
this early hour, the effulgence up to the zigzag x x was very great. I could not see any Diffuse Light on the left ;
and on the right, or upper side, it was not very distinct. At 2h 45m the light began to stretch slowly along the
horizon on the right, showing the first beginning of dawn. At 2" 48m the effulgence noticed as to x x suddenly sunk
to y y, and was greatly dimmed. The suddenness of the change was remarkable. The Light was now grey,
having lost its warm yellowish tinge. At 2" 52'° dawn had fully come.
The boundaries of the Stronger Light given in the chart for this morning may be considered fully reliable. The
atmosphere was so clear, even down to the water, that stars were seen immediately on emerging from the horizon.
I thought, several times, that there were pulsations, but I could not be certain about them.
OBSERVATIONS ON THE ZODIACAL LIGHT.
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596 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 298.
FEBRUARY 28th, 1855: MORNING.
Lat. at 3*., 40° 51' S. : Lon. 57° 21' VV.
Sun rose at Sh. 45m.
Stronger and Diffuse Light at 3 o'clock.
Clouds since last entry (23d) until this morning. Was on deck at 2h. and found the Zodiacal Light, at that
hour, very bright ; but owing to cirri continually passing, I was not able to get boundaries till 3 o'clock. I cannot
speak with confidence of the lower or left-hand boundary, as the Milky Way and the clouds presented difficulties in
getting it ; but the upper or right-hand boundary I believe may be considered fully reliable. There was a portion
of more intense light bounded by the zigzag x x. Could not get any boundaries for Diffuse on the left. Dawn
came at about 3" 20".
OBSERVATIONS ON THE ZODIACAL, LIGHT.
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598 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 299.
MARCH let, 1355: MORNING.
Lat. at 3k., 39° 11' S. : Lon. 57° 12' W.
Sun rose at 5/<. 4~\m.
Stronger and Diffuse Light at 3 o'clock.
The sky cloudless, and extremely favorable for observations down to the very horizon, where stars showed themselves
immediately after passing its edge. I was on deck when the moon set, about 2h 30'"; but the sky was a long time in
darkening afterwards ; and I could not get fully reliable boundaries till 3 o'clock. Those given in the chart for the
Stronger Light may be entirely relied on. Those of the Diifuse, on the left, were imperfectly marked ; and, on the
right, they were also not easily made out. I thought I observed pulsations in intensity. There was- a portion
bounded by the zigzag x x far brighter than the rest, and of this I made these records :* 2'1 58'" very bright ; so to
3h 8im, when extremely bright; 3'' lHm, just dimmed greatly; 3h 19'", just now brightened; 3" 21m, very bright :
3" 26m, exceedingly so ; no further change till near dawn (3h 20'"), when it sunk down and dimmed, apparently the
eifect of dawn, which had come decidedly at 3" 31™.
This was a very good observation, and the boundaries may be considered fully reliable.
It ought to be noticed that, owing to our rapid change of longitude, my watch was five or six minutes too slow ;
the times given above, therefore, need correction.
a Previous to 2A. 58m. I thought, sometimes, I saw changes of intensity ; but was so uncertain, that I concluded it best not to record them.
OUSEKVATIONS O.V THE ZODIACAL LIGHT.
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fiOO OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 300.
MARCH 13th, 1855: EVEMSS.
Lat. -2-2° 55' S. ! Lon. 43° 6' W.
Sun set at GA. J5mi
f "A. 30m. 1
Stronger Light at { 8 0 V Diffuse at 7/i. 30m. and 8rt.
^ 8 3D )
Clouds ever since last date (1st), until this evening. Sky this evening clear, and favorable for observations. The
Zodiacal Light showed itself about 7" 10m ; but I did not get reliable boundaries till 7" 30™. At 7h 45'", it was very
bright. At 8" 45™, the right-hand boundary of the Stronger Light appeared pretty clearly to have slid over (as in
the chart), similarly to that on the left ; but I will not speak confidently of this, as it had then sunk considerably
towards the horizon. At 8h SO1", the Stronger and Diffuse Light seemed to have merged considerably into one ; and
it was difficult to get any boundaries for the former. I have given its upper boundary as it seemed to me for that
hour ; the lower one appeared to be as at S'1. At 9" 30m, the Zodiacal Light was still visible (though dim) below the
Milky Way, and seemed to show itself above this also ; but it did not give any reliable boundaries.
OBSERVATIONS ON THE ZODIACAL LIGHT.
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602 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 301.
MARCH 15th, 1855: EVENING.
Lat 22° 55' S. : Lou 43° 6' W.
Suii set at 6k. 12m.
Stronger and Diffuse Light at 7k. 30m. and Sh. 20m.
Clouds last evening. The sky this evening bright and clear, except a dark cloud in the west, which, gradually
ascending, finally put a stop to observations. Was able, however, to get reliable boundaries for the Diffuse, and
also on the upper or left side of the Stronger Light. Those for the lower side of the latter were interfered with by
the cloud, and I cannot speak of them so confidently.
OBSERVATIONS ON THE ZODIACAL LIGHT.
603
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604 OBSERVATIONS ON THE ZODIACAL LIGHT.
MARCH i6th, isssi
Lat. 22° 55' S. i Lon. 43° 6' W.
Sun rose at 6A. 6m.
Stronger Light at 3A. lum, and 4h.l Diffuse at 2A. IFm. and 4h,
A beautiful clear morning, and everything favorable for observations, I was on deck immediately after 2 o'clock,
and found the Zodiacal Light very strongly marked; but, from the interference of the Milky Way, giving a boundary-
only on the right hand or southern side, This one was well marked (as at a a in the chart), with a stronger patch
of light at b. But, although I then took the former to be the Stronger Light, it was doubtless only of the Diffuse
Light ; for, at 3h 15"1 and 4h, the boundaries of the Stronger Light were decidedly as those given in the chart, while
a a now as decidedly was the limit of the Diffuse Light. Indeed, at the earliest of the morning, as well as at the
latest of the evening observations, the Stronger and Diffuse Lights can scarcely (if at all) be distinguished from each
other— the former being dim, and the latter stronger than at the other times.
The moon rose about 4h. Jupiter's light is now getting to be troublesome in the morning observations.
OBSERVATIONS ON THE ZODIAOA.L LIGHT.
605
11
606 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 303.
MARCH 16th, 1855 : EVENING.
Lut. 22° 55' S. : Lon. 43° 6' W.
Sun set, at 6/i. 12m
( 7h. 30m.
Stronger and Diffuse Light at? « 0
( 8 30
Sky very favorable for observations, and, at I7h 30m, I was able to get boundaries, which may be considered fully
reliable. At 8" the sky was still favorable, and the Zodiacal Light was still bright ; but, soon after this, the Light
began to grow dim ; and, at 8h 30m, it had dimmed so much, that it was with some difficulty I was able to get bound-
aries. Those given in the chart, however, I believe may be relied on.
OBSERVATIONS ON THE ZODIACAL LIGHT.
607
608
OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 304.
MARCH 17th, 1855: MORNING.
Let. 22° 55' S.: Lon. 43° 6' W.
Sun rose at 6/1. (im.
( 3/i. lorn. 1
Stronger Light at< 4 0 >Dift"use at 3A. 15m., &c.
(4 30 >
Sky very favorable, and I watched all the changes of the Zodiacal Light from 3 o'clock till dawn. At 3" the
Light was yet dim, but gave reliable boundaries ; though, on the right, I was puzzled somewhat in getting them, as
they seemed to change. After a while I thought, suddenly, that the Light had dimmed considerably, and then came
to the conclusion that there were pulsations, not only in intensity of the whole, but also in the boundaries at the right.
Of these I began to take note, sometimes fully satisfied that there were pulsations, sometimes doubting and giving
up annotations of that kind. The following are my notes :
h. m.
* * *
At 3 20, bright, and at b.
3 21^, dimming.
3 23,, dim, and at a.
3 25, brightening.
3 26|, bright, and at b.
3 29, still so.
h. m.
(An interval of doubting.)
* * *
At 3 40, obviously dim, and at a.
3 42, brightening.
3 43, decidedly brighter, and at b.
3 48, very bright.
4 6, still so.
After 4" 6"', I could see nothing like pulsations. The brightness had now got to be very great, and I saw no
changes, till, by and by, it began to fade away, or rather to be merged in the dawn, which had come decidedly at
4" 48m.
OBSERVATIONS ON THE ZODIACAL LIGHT.
609
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610 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 305.
MA.RCH 17th, 1655 : EVESINO.
Lat. 22° 55' S. : Lon, 43° 6' W.
Sun set at 6A. llm.
( ?A. 30m. 1
Stronger Light at? 8 0 > Diffuse at 7A. 30m. and 8h.
( 8 30 )
The sky clear, and night very favorable for observations. Watched most carefully every change of the Zodiacal
Light ; for these changes were remarkably distinct, and, owing to the rapid change of angularity between the ecliptic
and horizon, were very rapid. The Stronger Light was well marked at 7h 20m, but I could not get reliable bounda-
ries till tea minutes afterwards. J thought sometimes that there were pulsations, and made the following record:
h. in.
At 7 51, brightened, and at b.
7 52, very bright.
Ji. in.
At 7 40, very bright.
7 43, still bright, and at b.
7 45, dim, and at a.
After 71' 52m it grew dimmer, and at 81' 10'" had dimmed considerably. At S'1 30™ it was still distinctly marked in
the sky, but the Stronger passed so gradually into the Diffuse, that it was difficult to say where its boundaries were.
At 9h the Zodiacal Light was still clearly innrkod on the sky, but no reliable boundaries could be got.
OBSERVATIONS ON THE ZODIACAL LIGHT.
611
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OBSERVATIONS ON THE ZODIACAL LIOUT,
No. 306.
MARCH 20th, 1855 (18th was Sunday): MOBJJI.VG.
Lat. 23° 55' S.: Lon. 4:ir- IV W.
Sun rose at 6ft. 7m.
( 2/i. 0?n.
Stronger Li«ht at 4/i. low. and 4/i. 311m.: Diffuse? 4 l:i
( 4 3D
Yesterday morning was cloudy, so also last evening. This a. m. went on deck at 2 o'clock, to examine carefully
with reference to the light seen in the morning at our farthest .southern latitude. Found at that hour a decided
Zodiacal Light impressed on the sky, and with the limits on the right at a a. This Light was very decided, and
also its boundary. On the left it increased gradually in strength towards a and ft Capricorn! ; but, on that side,
I could not get any reliable boundaries, neither could I make out any decided boundaries for the Stronger Light, it
passed so gradually into the Diffuse. Was up again at 3'' 3CP; but clouds interfered till 4h 15'", when I had an excel-
lent sky for observations ; the Stronger Light was at this time very strong, with boundaries well marked, and fully
reliable. In the chart is a remarkable change of the left boundary of the Stronger Light, between 4h 15™ and 4" 30ro:
so singular and remarkably great as to be at first sight quite doubtful (see chart). But there was a similar change
yesterday morning ; and to-day I gave particular attention to it, and, as the boundaries both at 4" 15m and 41' 30'" were
very decided, I think there cannot be any doubt on the subject. Of the other boundaries there was not any change
in this period. At 4h 30™, the Stronger Light was extremely brilliant ; but this effulgence, instead of being only
near the horizon, as formerly, extended up in a conical form quite to the upper extremity of the Light, tapering off,
however, in intensity as it ascended.
OBSERVATIONS ON TilE ZODIACAL LIGHT.
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OBSERVATIONS ON THE ZODIACAL LIGU?.
So. SOT.
MARCH 21st, 1855: MORNIM;
Lat. 22° r,y ,«.: Lou. 43° 6' \V.
Sun rose (Jfi. ~ m.
t •_'//. H,,.
Stronger Liylit at 3ft. 0/n. mid 4A. 3()m. : Diffuse at? 3 0
( 4 30
Sun's Ion. U- 19'.
Clouds last evening. Was on deck at 2 o'clock. The Zodiacal Light was very distinct, but was oiii'y a vdiit isL •
yellow patch in the angle between the Milky Way and horizon, thinning off gradually till it seemed to be lost at the
line a i'i , the boundary there being very indistinct. Again on deck at 3'1, when the Zodiacal Light was very distinct
all the boundaries very well marked, especially those on the left or north. The sky, so far, was very favorable for
observations : but at 4", clouds interfered ; these cleared away by 4h 30'", leaving all things again quite favorable for
observations ; and I had reliable boundaries, which I took with the greatest care. The Light was then very strong.
At 4h 43m it began to spread, and in a few minutes dawn had decidedly come.
OBSERVATIONS ON THE ZODIACAL LIGHT.
615
Oj ;
616 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 308.
MARCH 2ist, 1335 : EVENING.
Lat. 22° 55' S. : Lon. 43° 6' \V.
Sun set at 6A. 7.1»'.
Stronger Light at 8/(. 3Um. : Dill'use at 8A. 30m. and 9/i. Urn.
The moon did not set till near S'1 30™, when I was able to get an observation : sky clear and brilliant, bnt the
Stronger Zodiacal Light already so much dimmed, and so little of it left, as not to give very good outlines below; the
upper part is also not fully reliable. The boundary of the Diffuse Light given may be relied on ; the lower one of the
latter could not be had. At 9", the Light was still distinct, but dim, and would give no reliable boundaries for the
Stronger Light. The Diffuse was the same as at 8h 30m.
OBSKRVATIONS ON THE ZODIACAF. LIGHT.
017
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CIS OBSERVATIONS ON THE ZODIACAL LIGHT
No. 309.
MARCH 23d, 1855 : HOKNIXG.
Lat. 2'2° 55' S-: Lon. 43° 6' W.
Sun rose fi/i. '.!/«.
( 3/i. dm. i
Stronger Light at-' 4 0 > Diffuse at 3 and 4 o'clock.
(4 30 )
Clouds yesterday morning. Sky this ,1. m. very fine for observations. At 3", the Zodiacal Light, though distinct,
was rather dim, but gave reliable boundaries; though, on the right, or southward, it was difficult to get those of the
Stronger Light, since it passed so gradually into the Diffuse. So, also, afterwards. While looking at it, I thought
that at about 3h 20"' it suddenly brightened. Was on deck again at 4'' : sky good, and Light very bright. But at
4'1 22"', it seemed to become much dimmed, and to contract its limits: at 4" 28'" it was again very bright. Against
these last two changes, I entered on my record, made at the time, "no doubt of this." At 4'' 30m it was extremely
bright.
OBSERVATIONS ON TUB ZODIACAL LIGHT.
610
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020 OBSERVATIONS ON THE ZODIACAL Lin I!1?.
No. 310.
MARCH 24th, 1855: MORNING.
Lat. 22° 55' S.: Lou. 43° 6' W.
Sun rose at 6/1. Win.
f 3A. dm.
Stronger and Diffuse Light nt< 4 0
( 4 30
Was on deck at 3 a. in., and found the sky very favorable for observations. The Zodiacal Light was dim, but gave
good outlines. About 3h 10™, the Stronger Light had increased considerably, with a more effulgent portion at its
central part, along the line of the ecliptic.
Again on deck at 4h ; and as the morning was in every respect remarkably favorable, except the radiance of
Jupiter, I watched carefully and long to see whether there would be pulsations. The Stronger Light was very bril-
liant, and continued so, till at 4'1 13m, I noticed that it had suddenly dimmed very much, with its lateral borders con-
tracted. At 4h 20m, it had spread again, and had brightened once more. At 4h 21m, it was very bright. I thought
at the time that there could be no uncertainty about these changes. I did not notice any others. Dawn about
4h 48'".
OBSERVATIONS ON THE ZODIACAL LIGIIT.
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622 OBSERVATIONS ON THE ZODIACAL L1GUT.
No. 311.
MARCH 26th, 1855 (25th was Sunday): MORNING.
Lat. at 3ti. 30m., 22° 8' S. : Lon. 39° 26' W. .
Sun rose at 6/1. 9m.
Stronger and Diffuse Light at 3/<. 2()m.
Was on deck at 3 o'clock this a. m. ; but clouds prevented my getting outlines till 3" 20m, at which time the sky
was very favorahle lor observations. Soon after this, clouds interposed : continued cloudy during the remainder of
the morning.
OBSKRVATJONS ON THE ZODIACAL LIGHT.
623
624 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 312.
MARCH 23th, 1855:
Lat. at 4A , 19° 32' S. : Lon. 36° 13' W.
Sun n.se at 0^. 9m.
Stronger and Diffuse Light at 4/i. 0«i. and 4/i. 3lvm
Cloudy yesterday morning. Clouds also this morning, till near 4 o'clock, when the sky became very favorable for
observations. I was able, at this time, to get boundaries with great precision ; and so, also, at 4" 30m. At 41' 40m,
there seemed to be a sudden dimming of the Stronger Light. Dawn at 4'1 45'".
OBSERVATIONS ON THE ZODIACAL LIGHT.
625
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626 OBSERVATIONS ON THB1 ZODIACAL LIGHT.
No. 313.
MARCH 29th, 1855: MORNING.
Lat. at 4/i., 17° 24' S. : Lon. 35° 10' W.
Sun rose at G!>. 9m.
( 3A. Om. 1
Stronger Light at< 4 0 > Diffuse 3A. and 4/<.
( 4 30 )
Was on deck at 3 o'clock, and found the sky clear and very good for observations. The left or northern bounda-
ries of the Zodiacal Light were well marked : on the right hand, or southward, the Stronger Light passed more
gradually into the Diffuse ; but still it gave very good boundaries. All those given at 3b, 4", and 4h 30m, in the chart,
appeared to me to be fully reliable. At 4h, found the sky still very favorable ; the Stronger Light bright and cone-
shaped. Thought I saw pulsations; but was too uncertain to record them, till 41' 16m, when there seemed to be a
sudden and great dimming of the Stronger Light, and it then sunk down to the zigzag «. At 4" 20m, it had con-
tracted to b b, leaving of the Stronger Light only the small patch within that zigzag, greatly dimmed from what the
Light was at 4h. My record then goes on: " 4" 25m, still dim ; about 4h 26m, brighter ; 4" 27£m, dimmed ; 4" 29^"',
brighter, and has shot up once more into the cone shape ; 41' 38'", quite bright, still cone shaped, but brightest within
the zigzag a; 41' 43m, very bright within the zigzag a ; 4h 45m, is breaking bounds and spreading at the horizon ; 41'
48m, dawn has come."
OBSERVATIONS ON TUB ZODIACAL LIGHT.
627
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628 OBSERVATIONS ON THE ZODIACAL LIGHT,
No. 314.
APRIL 4tb, 1855: EVENING.
Lat. at 8A., 1° 37' N. : Lon. 37° 3?' W.
Sun set at 6A. 3^m.
Stronger and Diffuse Light at 7k. 12m.
Clouds since last date (29th ult.) until this evening. Sky now sufficiently clear, at 7" 12m, to allow me to get the
southern boundaries of the Zodiacal Light, hoth of the Stronger and Diffuse. The northern boundaries were covered
by clouds. The eastern horizon was covered by clouds ; but the moon, now risen, soon broke through them, and
put a stop to observations for the evening.
OBSEBVAT1ONS «i; 1H!<: ZODIACAL, LIGHT.
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630 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 315.
APRIL 9tb, 1855: EVENIKG,
Lat. at 8/«., 11° ]2' N. : Lnn. 45° 51' W,
Sun set at 6h. 7m.
(-7A. 30/n. 1
Stronger Light at <! g ^ )• Diffuse 8A. to 9A. 50m.
19 50 ]
Clouds since last date (4th) until this evening. Sky, to-night, very fine for observations, except a few passing1
clouds, which occasioned, however, no material interruption. The Zodiacal Light showed itself at Th 12'", hut I was
not able to rely upon its boundaries till 7" 3CP. Its course across the Milky Way is now quite marked and decided,
in the case of even the Diffuse Light; but the upper extremities of both are not well denned. Those (the upper) of
the Stronger Light became better defined as the night advanced : of the Diffuse Light, not so well. At 9h 50m, the
Light was distinctly marked, though now much dimmed, and its boundaries barely reliable.
OBSERVATIONS ON TIIIO ZODIACAL MGUT.
631
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(132 OBSERVATIONS Otf THE ZODIiCAL LIGHT.
No. 31 fi.
APRIL Illth, 1S35: EVEVIM-.
Lat. at h., 13° 5' N. : Lou. 47° -.211' \V
Sun set at tilt. 8i'".
( 7//.!>il-m. )
Stronger Light at/ 8 ail >Dift'use sit 7A. 20m., 8A. '20m., and ]( It, 35m,
fa 4ii J
Night very favorable for observations. Had an observation as early as 7" 20m. Soon after this, the Stronger Light
became very bright. I observed carefully to see whether there were pulsations ; but the brilliancy of Venus, now in
the way, made such observations difficult. I could not see any thing like pulsations. Could not make out reliably
the right-hand boundary of the Diffuse Light at 7'' 20'", on account of the Milky Way. At y" 40"' the Light wu- well
marked ; could not make out the upper end of the Diffuse. At 10'' 35m the Light still quite distinct, but now could
not make out the boundaries of the Stronger Light. It was merged in the Diffuse.
OBSERVATIONS ON TUK ZODIACAL UC11T.
C33
G31 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 317.
APRIL llth, 1855: EVENING.
Lat, at 8A, 15° 9' N. : Lon. 48° 56' W.
Sun set at Gfi. 10m.
Stronger Light at 7/i. 25m. and 8h. 45;«. : Diffuse at 7A. 25m. and 8h. 40m.
Sky troubled with flying clouds, otherwise very good for observations. In consequence of the clouds, I could not
get reliable boundaries till 7h 25m, nor again till 81' 45m. Could not make out reliably the upper extremity of the
Diffuse Light. At 10h the Light was still distinct, but dim.
Went on deck again at midnight. I thought there was a brightness at the west, at midnight, along the Zodiacal
Light course, but nothing certain could be made out. Tried a long time, as the sky was extremely favorable for
observations, and thought sometimes that I could get boundaries (nearly the same as at 8h 40m, but running higher
up); but finally came to the conclusion that both boundaries and the Light itself were all very uncertain.
OBSERVATIONS ON THE ZODIACAL LIGHT.
635
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80
636 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 318.
APRIL 13th, 1835: MORNING.
Lat. at 3A. 30m., 18° 5' N. i Lon. 51° 25' W.
Sun roee at 5/i, 48^m.
Stronger and Diffuse Light at 3h. 30m.
CIouc'ls last evening. Moon for some time in the morning, until this a. m. Went on deck soon after 3
o'clock ; the Zodiacal Light, though quite distinct, too dim to give reliable outlines till 31' 30°', At that hour,
though the Light was not strong, the boundaries were well marked, except that of the Diffuse on the right hand
(which I could not get at all); and those given in the chart may, I think, he fully relied on. The sky was extremely
favorable for observations.
I still continue to notice, during the morning, the excess of meteors in the eastern sky over that of all other parts
of the heavens. The officer of the deck reported a remarkably large one on the morning of the llth, with a track
which was visible, he thought, for several minutes.
Moon rose this a. m. at 3b 4fi'n.
OBSERVATIONS ON THE ZODIACAL LIOUT.
037
638 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 319.
APRIL J 3th, 1855: ETENINO,
Lat. at Sh., 20° 9' N. : Lon. 53° 19' W.
Sun set at 6A. IS^m.
Stronger and Diffuse Light at 7h. 30m., Sh. 30m., and 9A. 30m.
In getting the lower part of the boundaries, this evening, I was somewhat troubled by clouds ; but the sky above
was clear and bright, and the lines given for that part of the Light are quite reliable. At 9" 30m the Zodiacal Light
was still marked on the sky, but was quite dim. The sky at that time was very favorable.
OBSERVATIONS ON THE ZODIACAL LIGHT.
639
640 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 320.
APRIL 14th, 1855: MORNING.
Lat. at 4ft., 20° 59' N. : Lon. 54° V W.
Sun rose at 5ft. 46m.
Stronger Light at 3ft. 30m. and 4ft. 15m. : Diffuse at 3ft. 20m.
The atmosphere not very favorable, and clouds on the right ; still I was able to get reliable boundaries, except for
the Diffuse on the right, where I could not make them out. The Stronger Light seemed to brighten up about 4'1 15™,
as in pulsations ; but of this I could not be certain. The moon, together with an early dawn, put an end to
operations.
OBSERVATIONS ON THE ZODIACAL LIGHT.
641
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642 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 321.
APRIL 14th, 1655 : EVERISO,
Lat. at 8A,, 22C 31' N. t Lon. 55° 46' W.
Sun set at 6/1. 15m.
( *A. (!?». )
Stronger Light at <; '.I 0 > Diffuse at 8 o'clock.
( 9 30 )
Cloudy till 8 o'clock. Sky, at that hour, also troubled by flying clouds ; but the Zodiacal Light was very
strong, and I was able to catch outlines between the clouds. The Zodiacal Light this evening was very brilliant.
At 9" 30m the clouds had disappeared, and thy sky -was remarkably Him !'»!• observations. The Zodiacal Li^ht was
still quite strong.
OBSERVATIONS ON THE ZODIACAL LIGHT.
843
81
644 OBSERVATIONS ON THE ZODIACAL LIGHT,
Xo. 322.
APRIL 16th, 1855:
Lat. at 3/(. 30m , 25° 23' N. : Lou. 59° 19' W.
Sun rose at 5/i. 40?);.
Stronger Light at 3/i. 15m. and 4ft. 15m.: Diffuse at 3k. 15m.
(15th was Sunday.) Was on deck soon after 3 o'clock, and found the eastern portion of the sky very favorable
for observations. The Zodiacal Light, however, was dim ; and its boundaries were difficult to be made out. Soon
after this, a strong light began to grow up towards the north, its strongest portion under p Pegasi. I concluded
to wait for further developments before forming any opinion of its nature ; but at 3" 50™ clouds spread over the sky,
and put an end to observations for the morning.
OBSERVATIONS ON THE ZODIACAL LlttllT.
(M5
646 OBSERVATIONS ON THE ZODIACAL UGH?.
No. 323,
APRIL 16th, 1855: EVENING,
Lat, at 8h., 27° 04' N. : Lon. 61° 35' W,
Sun Bet at 6A. 21m.
i lh. 45m. }
Stronger Light at < 8 45 /Diffuse at 7/i. 45m. and 8k. 45m,
( 9 45 )
The night excellent for observations. The twilight is beginning to be long ; got my first observation at 7h 45a.
At I7h 55m, and thence onward, the Stronger Light was much the strongest (like the effulgence often noticed in the
morning) within the zigzag a a; this was still so at 8'1 45m. At &'' 4»m the Light had dimmed, but was still well
marked in the sky, and gave reliable boundaries.
OBSERVATIONS ON THE ZODIACAL LIGHT.
047
648 OBSERVATIONS ON THE ZODIACAL LIGHT.
Ko. 324.
APRIL 17th, 1855:
Lat, at 4ft., 27° 59' N. : Lnn. 62° 26' W.
Sun rose at 5'i. 37 »«.
Stronger and Diffuse Light at 3A. 15»i. and 4ft. 15m.
Zenith point at 3ft. 15»u , Lat. 51° 27' N, : Lon. 50° 50'.
The sky was very favorable, but the Zodiacal Light is now so dim as to make it very difficult to get reliable
boundaries. Even at 4h 15m, the boundaries of the upper part of even the Stronger Light could not easily be made
out. I am, however, using the greatest care in getting outlines, both at evening and morning, on account of their
importance for comparisons with those south of the equator. This morning, as yesterday, soon after 3h 30"", a bright
light began to grow up until it reached the boundary a a in the chart ; afterwards, towards 4h 37™, the Light within
the zigzag b b became exceedingly brilliant, as if the sun were just going to rise there. About 4h 41°' this appeared
to dim considerably ; at 4'1 43m dawn had come.
OBSERVATIONS ON THE ZODIACAL LIGHT.
049
=3
C50 OBSERVATIONS ON THE ZODIACAL LIGHT
No. 325.
APRIL 18th, 1855: MORNING.
Lat. at 4A , 30° 30' N. : Lon. 65° 39' W.
Suu rose at 5A. 34.im.
Stronger and Diffuse Light at 3A. 15m. and 4A 15m.
Zeiiich point at 3A. 15m., Lat. 53° 30' N. : Lon. 251°.
Clouds last evening. This morning not very favorable for observations, and I cannot speak with entire confidence
of the boundaries in the chart. I think, however, that they are correct. At 3h 201" there was a rapid, almost sudden,
increase of light within the zigzag a: at 3'' 25"', when I went on deck again, a more intense light appeared within
the lower zigzag by b b. The southern boundary of the Diffuse Light could not be made out.
OBSERVATIONS ON THE ZODIACAL LKJll t
051
052 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 326.
APRIL 18th, 1855! EVENING.
Lat at 8h., 32° 10' N. : Lon. G7°1G' W.
Sun set at 6/1. 2G.Jm.
Stronger and Diffuse Light at 9h. and \0ft.
The sky, this evening, was perfect for observations ; but the moon did hot set till 0 o'clock. The Stronger Light
was, at that hour, very brilliant below ; and was quite bright as far up as Prtesepe, above which, though dimmer, it
could still be traced. At 10h it was still very bright, the atmosphere being remarkably clear.
I have, in my recent markings ou the chart, drawn the Stronger Light as extending far up in the sky; but it must
be observed that its upper portion is very dim, sometimes ^scarcely to be made out. At 10h could not bound the
Diffuse Light reliably.
OBSERVATIONS ON THE ZODIACAL LIGHT.
C53
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(01 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 32T.
APRIL 19th, 1855: MORNING.
Lat. at 4A., 33' 12' N. : Lon. 63° 1C' W.
Sun rose at 5A. 30m.
Stronger Light at 3';, 15m. and 44. I.r>»n. : Diffuse at 3ft.
Zenith puint at 3V] 5m. , Lat. 55° 30' N. : Lon. 252°.
The sky, at 3h 15m, very favorable, except some clouds on the left, near the horizon. I observed between the
clouds that the effulgence which I have lately marked at a a was already there ; but I could not get its boundaries.
At 4h 15m the eastern sky was cloudy below, allowing me to see only the upper ends of the Stronger and Diffuse
Light : on the right, no part of the Diffuse boundaries could be made out reliably.
OBSERVATIONS ON THE ZODIACAL LIGHT.
055
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656 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 328.
APRIL 21st, 1S55 : MORMXO.
Lat. at 3A. 36m., 37° 38' N. : Lon. 73° 9' W.
Sun rose at 5/i. 22m.
Stronger and Diffuse Light at 3//. 3l)m.
Clouds yesterday. The sky, this morning, was not favorable, the atmosphere being full of moisture ; and I will
dot speak with confidence of the boundaries given. On the right, or southern side, I could not get any at all.
Blowing a gale.
OBSERVATIONS ON THE ZODIACAL LIGHT.
657
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658 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 329.
MOON ZODIACAL LIGHT.
OCTOBER 21st, 1853.
Lat. 22° 11' N. : Lnn. 1 13° 35' E.
Sun set at 5^. 28m.
I 8h. 12m.
Observations recorded at< 8 15
^8 17
This evening, as the time approached for the moon's rising, I turned to see whether there might be a lunar
Zodiacal Light. I have often made this attempt during the cruise (see especially March 29th, 1853*), but, until
this evening, never could succeed to my satisfaction — probably in consequence of my looking too far up, and expecting
this light too much to resemble the sun's Zodiacal Light. Last evening, at 7'' SO"1, while finishing my observations
in the west, the quartermaster on duty said to me, " The moon is going to rise." I went over soon after to look at
the sky, and was struck at once with some resemblance to the sun's Zodiacal Light, but was too uncertain to do more
than to watch it carefully. There was also scarcely time to get my star-charts and to make annotations. By-and-by,
however, the sudden lateral spread of light (exactly like that in the morning, when the Zodiacal Light changes to
that of dawn or atmospheric light) was so striking as greatly to remove my doubts. It was then, however, too late
for taking outlines. So I was prepared this evening. At I7" 56m, a faint and rather doubtful light began to appear
from the Pleiades down, about the line of the ecliptic. At 8h 2™, it was of a pretty decided character. I now sent for
Lieut. M , to request him to assist rue with his judgment. At 8h 10'", when he got on deck, there could be no doubt.
He saw the light at once. It was exactly in the bounds of the sun's Zodiacal Light, with the shape this latter assumes.
It extended rapidly, still, however, keeping within the Zodiacal Light bounds. Its boundaries, at 8" 12m, 8'1 15"',
and S'1 IT'", are given in the chart. It kept these last bounds till 8" 22'", when it suddenly broke limits, and spread
laterally so fast, that, in two minutes, no definite boundaries remained. The resemblance to the first breaking of
morning dawn was very striking. Lieut. M agreed with me in all the above remarks, except the resemblance
to the morning light breaking bounds suddenly, which last he has not observed.
* The record in my MS. for March 29th, 1853, was as follows :
"I have been trying to see whether there is any Zodiacal Light by the moon, which is now in a fnvorable condition for ir, if there is any, and have, at times,
thought that there is such light; but I cannot get hold of any thing reliable. There is n i doubt, however, that, when the moon rises now, its light, cone-
shaped or triangular, is first shown at the bottom of the Zodiacal Light place. It was so, very decidedly, ou the 27th instant, when the moon was nearly at
full, and the horizon was clear. This evening the horizon was obscured by cirri; but. at 'Mi. .">!lm., 1 had an observation of a light on the ecliptic, parabolic in
shape, 5'2° in width, and ascending to 25° above the horizon. At !)A. 56m. it extended (>^0un the horizon, and rose to a height of 32°. Then it ascended
quickly to a height of 35° from the horizon, where it remained till the sky was all brightened rapidly by the approaching moon, which rose at ten minutes
past 10 o'clock. " (The Lat. then was about 2° N. : Lou. about 104° 21' E.)
OBSERVATIONS ON THE ZODIACAL 1,10 liT
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600 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 3(10.
MOON XODIACAL LIGHT.
OCTOBER -2-iA, 1S53.
Lat.225 23' N. : Lon. 113° 32' E.
Sun set at jh. 27m.
Observations at 9/i. and 9A. 5m.
Zenith point at 9 o'clock, Lat. 20° b' N. : Lon. 356° 30'.
At 8h 47m the eastern sky began to show a speck of illumination. This gradually increased, keeping within the
bounds of the sun's Zodiacal Light. Took its boundaries at 9'1 and at 9h 5m, as in the chart, its northern end below
•Capella being hidden by clouds, which came gliding along, and prevented further reliable observations. At 9h 6™
there .was a very strong light, the star ft Tauri being about its centre. At 9h 10"' the Light suddenly broke bounds
as before, and spread laterally and upward. Could not tell exactly when the moon rose, the island of Cumsingmoon
being in the way.
OBSERVATIONS ON THIS ZODIACAL LIGHT.
061
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662 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 331.
MOON ZODIACAL LIGHT.
FEBRUARY 14th, 1854.
Lat. 35° 19' N. : Lon. 139° 43' E.
Sun set at 5A. 36m.
Observations at 6A. 50m., Gh. 54m , and 6A. 56m.
Since my last notice of the moon Zodiacal Light, I have been watching anxiously for another opportunity for snch
observations; but the clouds have prevented until this evening, when I had an excellent one. _ There is no land
obstruction, and this evening the sky was clear, except a dense haze, confined closely to the horizon. The moon rose
before the night had entirely set in, but still the darkness was sufficient to afford a good exhibition of the Light,
which was as follows : At 6h'40m there was a faint blush in the usual Zodiacal Light path, but not distinct enough to
give outlines. At 6" 50™ it was decided, and I got boundaries as in the chart: 6h 52"° the light was very bright,
limits as before : 6h 54'" limits enlarged, light nearly as strong as the best Sun's Zodiacal Light : 6" 55m the disc of
the moon showing itself, but with enlarged bounds of the Zodiacal Light, as in the chart. At 61' 57m the light had
broken bounds, and was now atmospheric moonlight. The breaking bounds was very sudden and rapid.
NS ON' TiilO XuDlAOAi, i.KillT.
604 OBSERVATIONS ON THE ZODIACAL l.IGUT.
No. 332.
MOON ZODIACAL LIGHT.
FEBRUARY 15th, 1851.
Lat. 3.j° 19' N. : Lon. 139° 43' E.
Sun set at 5fi. 364m.
Observations at7A. 35m. ,7A. 37m., 7A. 39i»., 7A. 4'i'»., ninl 7A. 43m.
The eastern sky was excellent for observation, except a belt of whiteness generally along the horizon, and so wide
as to make it difficult to get the boundary at the southern side of this Zodiacal Light, except at its upper part. The
observation was very satisfactory. At 71' 30m I thought I could see a very faint tinge in the usual Zodiacal Light
boundary, but was doubtful : 71' 33m a tinge, not doubtful, but too indefinite to give boundaries : 7" 34"', decided : 7"
35m, got boundaries (see chart): 7" 37"', bounds as before, but Light stronger : 7" 43'", very bright, especially about
its lower end : 7h 45™, as in chart, bright : 7" 47m, general light beginning, and boundaries not so clear ; but at this
time, and till 7" 53m, seem to be about as at 7" 45'" : 7h 52m, disc of moon begins to show itself, but in the haze : 7h
53"1, general moonlight.
The difference between the elevation of the Light, this evening and the 14th, was doubtless caused by the long
twilight here ; in consequence of which, darkness on the 14th had not fully set in at the time of that observation, and
thus the Zodiacal Light was not fully revealed that evening.
OBSKIH ATIONS ON THE ZODIACAL UtillT.
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G6G OBSEEVAT10NS ON THE ZODIACAL LIGHT.
No. 333.
MOON ZODIACAL LIGHT.
FEBRUARY 17th, 1854.
Lat. 35° 19' \.: Lon. 139° 43' E.
Sun set at 5/i. 40m.
Observations aU 9 40
^ 9 45
* * * * At the proper time I turned towards the east to make observations, fearful, however, that some clouds
that came hurrying on would interfere. The evening, in other respects, was very favorable ; the large stars showing
themselves distinctly, immediately after being lifted above the horizon. At 9h 37m, the Light being then quite strong,
I got the boundaries marked a ; at 9b 39"' b ; the Light then being very bright. At 9'1 40°' the boundaries were at c,
and the Light was then as bright as the sun's Zodiacal Light ever is. Clouds then slid over, and I could no longer
get reliable outlines ; but the Light, as seen between the clouds, still remained very strong. At 91' 46"1 the Light
broke bounds and spread ; and, at 9h 52'°, the disc of the moon began to appear.
OBSERVATIONS ON THE ZODIACAL, LIGHT.
667
668 OBSERVATIONS ON TUB ZODIACAL LIGHT.
No. 334.
MOON ZODIACAL LIGHT.
FEBRUARY 18th, 1854.
Lat, 35° 19' N.: LCD. 139° 43' E.
Sun set at 5/i. 41m,
CWh. 44m.
in 47
•Stronger Light at 10A. 58m. and 1 1A. 2m, : Diffuse at< - „
10 55
111 1
As the moon approached the eastern horizon, I turned to see what it would produce. At lO"
39m, the sky began to show a blush of light ; 10h 44ra, got boundaries as at a; 101' 47ra, as at b, then very bright below
Spica, not above: 10" 50m; very bright to 51 Virginia (m on chart); 10h 51"', boundaries to line c; 10h 53"1, at d;
I0h 55m, as at e ; 10" 58"', a stronger light, boundaries marked by line x (it had shown itself before, but I did not take
its boundaries); llh 1'", as at/; II1' 2m, Stronger Light at y y ; Diffuse as at last; 11" 3-£ra, the edge of the moon's
disc shows itself. The eastern sky was remarkably fine for observation-.
OBSERVATIONS ON THE ZODIACAL LIGHT.
669
670 GBSERVATIONS ON TEE ZODIACAL LIGHT.
No. 335.
MOON ZODIACAL LIGHT.
MARCn 18th, 1854.
Lat. 35° 26' N-: Lon. 139° «' E.
Sun set 6A. 5m.
f 9A. 46ni.
9A. 50m. 9 49
9 54 Q ,,
9 56 j [9 55
Tlie sky at the eastward was clear, except a narrow cloud near the horizon ; and at 9h 30m I began to watch, to
see what the moon, now approaching the horizon,- would produce. There was at this time a singular paling of the
sky — indeed, I think I may say a positive light — within the dotted marks on the chart. I called one of the quarter-
masters, and asked him if he could discover a brightness along there, which he immediately did ; although when I
asked him to bound it, he placed it a little further to the north than 1 did. After a while the moon's Zodiacal Light
clearly commenced, and at 9h 46m, &c., I got the boundaries as in the chart. At 9h 50™, a Stronger Light began to
show itself decidedly, and I took its boundaries also at 9'' 54™ and 9h 56m (see x y z). At 9" 57m, the disc of the
moon began to show itself above the horizon. I notice that its light breaks bounds arid spreads quicker on the
right (or southwardly) than on the left. The streak of cloud did not interfere,, materially, with the observations.
OBSERVATIONS ON TUB ZODIACAL LIGHT.
671
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672 OBSERVATIONS ON THF ZODIACAL LIGHT.
No. 336.
MOON ZODIACAL LIGHT.
MARCH 21st, 1854: Just after midnight.
Lat, 35° 26' N. : Lon. 139° 42' E.
r»*o fj?-
Stronger Light at i 16 > Diffuse I ,r
I20 j 18
Eose at midnight, to watch for the moon's Zodiacal Light. At 12h 8™, the eastern sky began to exhibit a flush ; at
12h 10m, got boundaries ; and thence on to 12" 19m, as in the chart ; at 12" 12im, 12" 16m, and 12" 20™, took bounda-
ries of the Stronger Light ; 12h 20m, the moon's disc showed itself in some haze along the horizon. The sky was
very favorable ; and although the moon was now entering her last quarter, and her light was m>t at the strongest,
still the Zodiacal Light was very distinct and strongly marked. The observation was extremely interesting, on
account of the moon's distance from the equator, and also the great obliquity of the ecliptic to the horizon. Had
this light been merely a reflection from the atmosphere, its highest point would have been in a very different direc-
tion (up towards Arcturus) from what it was.
OBSERVATIONS ON THE ZODIACAL LIGHT.
673
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674 OBSERVATIONS ON THE ZODIACAL LIGHT.
TSTo. 337.
MOON ZODIACAL LIGHT.
APRIL 17th, 1854.
Lat. 35° 19' N.: Lnn. 139° 43' E.
Stronger Light at \Mi. a7»i. ami 11/t. 34m : Diffuse at 11A. '24m. and ll/i. 34:».
* * * Towards 11 o'clock, I turned towards the east, to watch for the moon's Zodiacal Light ; a haziness
along the horizon, and some distance up, together with approaching clouds, making the prospect there a very uncer-
tain one. Still, I had reliable results, though got with some difficulty ; and they are extremely interesting, on
account of the great obliquity of the ecliptic to the horizon. Yet, great as this was, the Zodiacal Light stretched
up along its old course, and the boundaries (except at the last, when I had to gather them from among the broken
clouds) were very distinct. The last observations, at llh 28", gave mo no limits at the highest part, clouds at that
place filling up the sky.
I thought this evening, as on one or two former occasions, that there was a paling of the sky far upward along the
ecliptic line, long before the Light became decided at the lower end — say for half an hour previously ; but I could
not be certain about it. The moon showed itself at II1' l!2m ; but it was so dimmed by the haze of the horizon, that
the Zodiacal Light continued well defined fur six rninutps af'tov wanl .••..
OBSERVATIONS ON THE ZODIACAL LIGHT
075
OBSERVATIONS UN TDK ZODIACAL UUHT.
No. 338.
MOON ZODIACAL LIGHT.
MAY 15th, 1834.
Lat. 40° 31' N. : Lon. 142° 59' E.
Zenith point, Lat 48° 37' N. : Lon. 267°.
The eastern horizon had some haziness over it, yet not so great as to prevent the moon's disc from showing itself
(though dimmed) as soon as it readied the horizon. Watched attentively for an hour previous to its rising, in order
to catch every appearance of the sky. Thought sometimes that there was a paling of the sky up as high as Spica,
from &'1 37m on ; hut this was very uncertain. On the whole, I rather conclude that there was none. Except the
haziness, the evening was a very interesting one ; for the angle of the ecliptic with the horizon is so small, that the
moon approached very slowly, and so gave me ample time for observations, after its light first hegan decidedly to
show itself. The moon was also now ahout its furthest possible distance from the equator ; and this, together with
the small angle of the ecliptic to the horizon, gave excellent opportunities for testing whether the Light is a reflection
from the atmosphere piled into an equatorial ridge, or from something else. The conclusion soon became clear to
my mind, that the former could not be the case. (See also the chart.)
At 10h 8m the sky began to show a faint blush, decidedly light from the moon. Could not get boundaries till
10" 20m, when they were as in the line a; at 10'1 23m, they were as at b ; 10" 27™, still at b, but light strengthened ;
10h 28m, as at c; and now there might, perhaps, be called a Stronger Light, with the boundaries at m ; but the
haziness prevented this from equaling former exhibitions of that kind. At 10h 29™, the upper edge of the moon
showed itself above the smooth-sea horizon ; but the haze there kept it so dim, that the boundaries c and m still
continued till 10" 31ra.
The quick rounding off of the Light on the right side, as at a; a; x, was quite striking this evening. Had it not
been Zodiacal Light, it would have naturally extended slantingly off on the right as well as on the left.
OB31SIIVAT10S3 ON TUK 2'.)1MAGAL LIGHT.
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678 OBSERVATIONS ON THE ZODIACAL LI6H7.
MOON ZODIACAL LIGHT,
JULY 14th, 1854.
Lat. 25° 9' N. : Lon. 121° 46' E.
Sun set at 6A. 4e£m.
Stronger Light at 10A. 20m. : Diffuse at lOh, 16m. and If ft. Wm,
I watched, last evening, for a moon Zodiacal Light, tut streaks of clouds in the east prevented any reliable rosults.
This evening the sky was very favorable, and the Zodiacal Light was strongly marked ; and was the more striking,
because the ecliptic made a very low angle with the horizon. Took boundaries as at 10h 16m and 10h 19m : and at 10*
20m the Light was so strong below, that I also took boundaries for a Stronger Light, as in the full line in the chart.
Soon after this, the light spread suddenly on the right band, so as to stretch out like that on the left — caused,
probably, by the moon's rays having now reached our atmosphere. This rapid stretching out on the right was very
striking.
OBSERVATIONS ON THE ZODIACAL LIGHT.
G79
680 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 340.
MOON ZODIACAL LIGHT.
SEPTEMBER 12th, 1854.
Lat. 22° 14' N. : Lon. 1 15° 18' E.
Sun set at 6^.2im.
Stronger Light at 9!i. 44m. : Diffuse at 9/i, 42m. and 9A. 44m.
****** As the sky was so favorable for observations, I intended to watch for a moon Zodiacal Light,
though the rnoon was not at its best time, being several nights after the full ; but I was not on deck soon enough for
its first show of light. However, I succeeded very well, as may be seen from the chart. The fuff line gives the
boundary of a Stronger Light, which began to show itself about 9" 44ra. At 9" 45Am the Light broke bounds on the
right, and, soon after, on the left ; but there seemed to be, from this time on, for a while, a streak of paled sky along
the ecliptic, running far up into the sky. I was not sufficiently certain about it, to warrant my putting it down on
the chart ; and it was over too soon for my getting other judgment than my own to bear on it. At 9h 50"1 the edge
of the moon appeared above the line of the smooth horizon.
OBSERVATIONS ON THK ZODIACAL LIGHT.
081
682 OBSERVATIONS ON THE ZODIACAL LIGHT
No. 341.
MOON ZODIACAL LIGHT.
FEBRUARY 3d, 1855.
Sun set 6/1. 57m.
Lat. 33° 1' S. : Lon. 71° 41' W.
Observations at 8A. 23.n., 8/1. 27»i., and 8/>. 29m.
This evening, the sky being quite free from clouds and tolerably bright, 1 succeeded in getting a moon Zodiacal
Light, as in the chart. The proximity of the ecliptic to the horizon, however, makes the evening Zodiacal Light
now less striking than it was in lower latitudes. The upper edge of the moon's disc showed itself at 8" 25° ; but,
there being a haziness along the horizon, the Zodiacal Light gave boundaries for two minutes afterwards.
OBSERVATIONS ON TUii ZODIACAL UGUT
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684 OSSK.RVATIONS ON THE ZODIACAL I.ICIIT.
No. 342.
CASSINI'S OBSERVATION.
FEBRUARY 27tli, 1(^5: EVENING.
Lat. 48° 51' N. : Lon. 2 ~> 22' W.
(Compare mine of February 24th, and 25th, 1854, Nos. 123 and 124; but in this, and all the subsequent compari-
sons, we must bear in mind that Cassini's latitude was north of my own ; often considerably so.)
" Le 2*7 Fevricr [1685] le terme septentrional do la lumiere passait par 1'espace qui est entre la tete d' Andromeda
et 1'extremite de 1'aile de Pegase, par la premiere d' Aries, et au-dela des Pleiades, jusqu'au col du Taureau.
" Du cote du midi, el touchait le plus septentrionale des trois claires de la gueulc de la Baleine, et celles qui sont
dans la caisse du Taureau." [P. 160.]
OBSERVATIONS ON THE ZODIACAL UGIJT.
685
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( 8G OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 343.
CASSINI'S OBSERVATION.
MARCH 22.1, IfiSo: EVENING.
Lat, 48° 51' N.: Lon. 2'J 22' W.
Observation at T/i. 50m.
(Compare mine of March 20th, 1854, No. 128.)
"Le 22 cle Mars [1685] a 7 heures 50 minutes, la lumiere s'etendait jusqu'a la tetedu Taurcan, ou elle se perdait in-
sensiblement. Du cote du septentrion elle compn'nait k-s trois plus luisantes d' Aries, et du cotedu midi elle rasait
Menkaret les etoiles de 1'epaule du Taureau/'
OBSERVATIONS ON THK ZODIACAL LIGHT.
UHT
CS8 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 344.
CASSINI'S OBSERVATION.
AI'IUL 21st, 1685 : EVENING.
Lat. 18° 51' N.: Lun. •> -' 22' W.
Observation at 9 o'clock.
Of
(Compare mine of April 21st, 1854, No. 141; and notice particularly the coincidence in the unusual positions
the Zodiacal Light, as regards the ecliptic.)
" Le 21 d'Avril [1685], a 9 heures du soir, le ciel etant fort serein, la clarte comprenait du cote de septentrion, le
pied ct la jambe australe de Persee, et le pied boreal avec le genou austral d' Auriga. Elle traversait la Voye de
Lait, et allait finir a 1'etoile dans Fepaule du precedent des Jumeaux, laquelle fait un triangle equilateral avec les
deux tetes. Sa partie meridionale comprenait 1'oeil boreal du Taureau, et laissait a cote 1'ceil austral. Son ex-
tremite meridionale passait entre les deux comes du Taureau, Liissant la corne austnile du cote du midi. Elle decli-
nait done evidemment de reclipti(|iic vers le septentrion, comme elle avait fait vers la fin d'Avril de 1'annee 1083, qui
est la circonstance principale qui me fit penser a 1'hypothese de la situation de cette luniicre selon un plan qui con-
vienne a pen pres avec celui de 1'equateur du soleil." [P. 1G2.]
OBSERVATIONS ON T1IR ZODIACAL IJGIIT.
1)89
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690 02SEUVATIGNS OK THE ZODIACAL LIGHT,
No. 345.
CASSINI'S OBSERVATION.
SEPTEMBER 9th, 1685 : MORNING.
Lat. 48° 51' N. : Lou. 2° 22' W.
Sun rose at 5/i. 33m. Observation at 3/i. If™.
(Compare mine of September 20th, 1854, No. 217.)
" Le 9 cle Septembre, 1685, a 3 hcures ct un quart du matin, la lumiere paratssait du cote d' orient beaucoup plus
claire que la Voye cle Lait, avec laquelle elle se confonclait a son extremite. Elle passait sous la tete des Jumoanx,
qu'elle laissait au norcl, et convrait toute 1'Ecrevisse. A 3 heures et 3 quarts elle enfermait la tete et le col du Lion
avec la tete del'Hydre. Le ccenr du Lion etait au milieu de sa largeur. Solon cette observation, la largeur de la
lumiere etait tie 27 ou 28 degves, et elle etait aussi partagee a pen pros egalement par 1'ecliptique. Sa longueur
entre le soleil et la Voye de Lait etait de 79 degres. A 4 heures le crepuscule paraissait com me line bande Iniuineuse
de la largeur d'environ 10 degres, qui n'cfFacait pas neanmoins la limiiere extraordinaire, ni la Voye de Lait, en
sorte quo 1'on voyait la lumiere laire un angle avec le crepuscule d'nu cote, et avec la Voye de Lait de 1'autie."
OnSKRVATiOXS ON TUB ZODIACAI, UGIIT
091
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OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 346.
< ' A s s i N r s o H y K K v A T I o N .
SK!TKMHr,l; 2
L-vt. is ;>V N : Lou. 2 : 22' W.
Sun rose f>//. 5
(Compare mine of September 27th, 1854, No. 221 . )
" Septembre 27, 1685. — A 3 heures du matin je vis la lumiere sur If signe .hi Lion et de 1'Ecrevisse, on elle se ter-
minait du cote d'occident, se perclant dans cette constellation si insensiblement qu'on avuit quelques fois de la peine
il 1'appercevoir. Les piedsdu Lion etaient a son term,1 nn'ndional; le dos et la queue du Lion ;\ son terine septentri-
onal. II est done evident quo 1'ecliptique ne divisait pas e^aleinent la lavgeur de la lumiere, mais quo sa plus grande
partie restait du C(Aitc du septentrion, puisque le cosur du Lion, qui a un pen de latitude septentrinnale, etait plus pros
du terme meridional que du septentrional. Sa lon^iU'ur jusqii'au soleil etait cle 70 degres. A 4 heures 35 minutes
le crepuscnle commencait a paraitre, et la lumiere extraordinaire* paraissait encore depuis la eeinture de la Vierge
jusqu'a 1'Ecrevisse, que etait entieremeut dans la lumiere. La partie septentrionale de la tete et du col du Lion etait
dehors du cote du septentrion ; et la tete de 1' Hydro etait dehors du cote du midi: ainsi sa largcur en cet endroit
etait de 22 degres." [P. 173.]
[I have not attempted to draw boundary-lines according to this last annotation (at 41' 351"), as I cannot understand
it clearly.]
° In these annotations, Cassini often calls the Zodi ical Li^ht "lit InmiSiv ij.ti-'H."-ilii'uiire."
ON TliP: :'/,)•>! ACAL LIG1IT.
093
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694 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 347.
CASSINI'S OBSERVATION.
•
NOVEMBER 27th, 1685: MORNING.
Lat. 48° 51' N. : Lon. 2° 22' W.
Sun rose at 1h. 33m.
(Compare mine of November 27th, 1854, No. 246.)
"Le 27 Novembre [1685], a 5 benres clu matin, la lumiere sevoyait etendresur la constellation cle la Vierge: elle
passait entre la meridionale de la ceinture et la moyenne des trois clans la me me ceinture, laissanfc an septentrion
toute 1'aile septentrionale. L'epi de la Vierge la bordait du cote meridional, et vers 1'horison elle s'elargissait jux-
qu'au pied septentrional: du cote d'occident elle s'etendait pres de Saturne, qui etait au 29 clegres de la Vierge, a la
distance de 67 clegres du soleil.
A 5 heures 25 minutes Jupiter parut sur 1'horison et semblait etre au bord meridional de la lumiere, quoiqu'il
cut un pen de latitude septentrionale; et du cote du septentrion elle :i|>|>rur!iait des etoile.s qui sontdans le col du ser-
pent d'Ophiucbus. D'ouil parait que la lumiere etait presque toute du cote du septentrion, a 1'egard de 1'ecliptiqae,
et qu'elle etait beaucoup etroit qu'au mois precedent, sa largeur dans la ceinture de la Vierge n'etant que cle 5 degres."
[I had drawn the southern boundary according to his description, but, by some inadvertency, it has not been in-
serted in the chart here given. The reader will perceive that it appeared to Cassini to be a few degrees north of
the ecliptic.
OBSERVATIONS ON THE ZODIACAL LIGHT.
f.l»5
(JS.G OBSERVATIONS ON THE ZODIACAL MG11T.
No. 348.
CASSINI'S OBSERVATION.
DECEMBER 4th, 1'GSo : MOBNIXO.
Lat. 48-"' 51' N. : Lou. 2^ 22' W.
Sun rose at7/i. 43m.
(Compare mine of December 18th, 1854, No. 257.)
" Le 4 Decembre [1685], a 5 heures 15 minutes du matin, hi lumiere s'etendait sur la parfcie inferieure de la Vierge,
et se terrninait insensiblernent pres de la ceiuture a G8 degres de distance du soleil. Elle comprenait le,s autres etoiles
de la Vierge au-dessous de la ceinture jnsqu'aux pieds, et cellos quo Ton voyait de la Balance, et s'approchait de cellos
dn ventre du serpent d'Ophiuchus. L'epi de la Vierge en etait ua pen eloigne du cote du midi; sa largeur sur la
Balance etait de 15 degres. Jupiter, qui etait all degres du Scorpion, etait compris dans la clarte, et y faisait comme
une breche: d'ou il parait que la lumiere etait pres^ue toute du cOte du septcntrion a, 1'egard de l'ecliptir|ue." [P.
175.]
OBSERVATIONS ON TUE ZODIACAL LIGHT.
f,!)T
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C98 OBSERVATIONS ON THE ZODIACAL IJGHT.
No. 349.
CASSINI'S OBSERVATION.
DECEMBER 25th, 1685: EVENING.
Lat. 482 5V N. . Lon 2o 22' W.
Sun set ih. 3m.
(Compare mine of December 20th, 1854, No. 262.)
" Le 25 Decembre [1685], au soir, apres le passage de 1'etoilc polaire par le meridien [say at 6h -I:]™], nous obscr-
vames cctte lumiere a 1'occident. Elle semblait se separer de la Voye de Lait dans la constellation d' Antimius ; son
terme boreal passait par la main d'Antinous, par les epaules et par le coude oriental d' Aquarius, et semblait arriver
jusqu'aux etoiles meridionales d\\ Poisson Austral, qui smitpres de reclijitique. Ainsi .son terme oriental etait dis-
tant du soleil de 76 degres. Du cote du midi elle comprenait Venus, qni etait a 18 degres du Capricorne, avec un
degre et demi dc latitude australe ; et elle s'etendait un degre de jilus vcrs le midi. Elle coraprenait anssi Mars, qui
etait a 7 degres et demi des Poissuns, avec un pen moins d'un di'gre de latitude australe; la plupart de la lumiere
etait done encore du cote du septentrion al'egard de 1'ecliptique; sa largeur sur la constellation d' Aquarius etait de
12 degres; rnais elle etait plus grande vers Antinous." [P. 17G.]
OBSERVATIONS ON TUB ZODIACAL LIGHT.
699
88
700 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 350.
CASSINI'B OBSERVATION.
MARCH 7th, 1687 : ETEKIHO.
Lat. 48° 51' N.: Lon. 2° 22' W.
Sun set 6/1. Vim.
(Compare mine of February 25th, 1854, No. 124.)
"Le 7 Mars, [1687], apres le passage du Grand Chien par le meridian [say at 7" 27m], on voyait la lumiere etendue stir
la queue du Poisson Austral, sur le lien des Poissons, sur la tete de la Baleine, et sur la constellation d' Aries, dontles
comes etaient d son estremite boreale, et 1'etoile qui est sous 1'ceil de la Baleine a son extremite australe [see a a in
chart], Elle passait par les Pleiades, et se terininait insensiblement aus etoiles qui sont dans le col du Taureau, et
un per. apres elle semblait s'etendre jusqn'a la Voye de Lait [see b b in chart]. Dans cette derniere observation, sa
IP snlojl etait d" '.ill d.Vn's, et sa largenr sur la constellation d' Avionot de la Balcin^ do 19 a. 20degres."
OBSERVATIONS ON THE ZODIACAL LIGHT.
701
702 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 351.
CASSINI'S OBSERVATION.
OCTOBER 15th, IBS" : MORNING.
Lat. 48^ 61' N. : Lon. 2° Tl' \\ .
Sun rose Gh. 25m.
(Compave mine of October ICth and 20th, 1854, Nos. 228 and 232.)
"Le 15 Octobre, 1687, a une beure et trois quarts du matin, a Fobservatoire, la lumiere se voyait faiblement siir
le col duLionetsurl'Ecrevisse, dont les etoiles les plus luisantes paraissaient a son terme meridional, et die semblait
s'etendre presque jusqu'a la-tete meridionale des Jumeaux. La partie plus evidente se terminait a un degre et demi
de 1'Ecrcvisse [at a on chart]. A 2 heures le cceur du Lion paraissait a un tiers de lalargeur dela lumiere, qui s'eten-
dait jusqu'a 1'eloile la plus claire du col.
"A3 heures 40 minutes la lumiere etait fort claire* au-dessous du cceur du Lion, jusqu'a un degre de hauteur sur
1'horison. Elle paraissait un pen concave du rule du midi, etplus convex du c-"te du septentrion.
" A 4 heures et un quart le terme austral de la lumiere etait presque perpendiculaire a 1'horison, et le boreal etait
incline vers le midi." [Pp. 201, 202.]
e On Sth October of this year, he also says : " A 4 heures et cleuii. la clarte' au-dessous du nrur du Lion e'tait tres grande, et la largeur de (•.•((,-
grancle clartc etait de 12 de'gre's" [the whole width of the Li.ulit ln-iuj; 11 dei;n.'i-s]. un tin- Inlli nf same iinnilh lie has a similar record. Thin, no
doubt, wn.-> what I have called in niy records effulgent l>:/lii, and which 1 have liumuK-d with zi^zay line's.
OBSERVATIONS ON THE ZODIACAL LIGHT.
703
704 OBSERVATIONS ON THE ZODIACAL LIGHT.
No. 352.
CASSINI'S OBSERVATION.
NOVEMBER llth, 1687 : MOKXIXCI.
Lat. 48° 51' N. : Lou. 2^ 22' W.
Sun rose 7/». Urn.
(Compare mine of November 20th, 1854, No. 241.)
" Le 14 Novembre [1687] , a 4 lieures et £, on voyait la lumie"re sur la partie de la constellation de la Vierge qui etait
sur 1'horison; elle se terminait a, la jarabe occidentale dit Lion pres de 1'ecliptique, ou un peu plus loin vers leventre.
La septentrionale de deux etoiles claires dans la ceinture de la Vierge etait au cote septentrional; la meridionale otait
presquc dans le milieu de sa largeur, ouun peu plus pres du cote meridional. Proche riiorison la lumiere s'.etendait
du cote du septentrion jnsqu'au genoiiil septentrional de la Vierge.
"A 4 heures 38 mimites Saturne parut pres du milieu de la lumierc, et un peu apres 1'epi de la Vierge s'etantleve
parut plus vers le septentrion.
"A 5 heures la partie de la lumiere qui comprenait Saturne et 1'epi de la Vierge etait beaucoup plus claire que la
Voye de Lait ; cette plus grande clarte n'arrivait qu'a 1'etoile meridionale de la ceinture de la Vierge [see a a in chart].
A 5 heures 48 minutes 1'aurore cornmeu9ant a paraitre, effaca peu-a-peu la lumiere." [Pp. 202, 203.]
OBSERVATIONS ON THE ZODIACAL LIGHT.
705
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