THE OBSERVATORY AT FLAGSTAFF
When, returning from Japan late in 1893, Percival Lowell found himself
quickly absorbed by astronomical research, he was by no means without
immediate equipment for the task. His mathematical capacity, that in
college had so impressed Professor Benjamin Peirce, had not been allowed
to rust away; for, when at home, he had kept it bright in the
Mathematical and Physical (commonly called the M. P.) Club, a group of
men interested in the subject, mainly from Harvard University and the
Massachusetts Institute of Technology. So fresh was it that we find him
using, at the outset, with apparent ease his calculus—both differential
and integral—tools that have a habit of losing edge with disuse.
Physically, also, he had a qualification of great importance for the
special work he was to undertake,—that of perceiving on the disks of the
planets, very fine markings close to the limit of visibility; for the
late Dr. Hasket Derby, then the leading practitioner in Ophthalmology in
Boston, told Professor Julian Coolidge that Percival’s eyesight was the
keenest he had ever examined.
One essential remained, to find the best atmosphere for his purpose. In
entering our air the rays of light from the stars are deflected, that is
bent, and bent again when they strike a denser or less dense stratum.
But these strata are continually changing with currents of warmer or
colder air rising and falling above the surface of the earth, and hence
the rays of light are being shifted a little from side to side as they
reach us. Everyone is familiar with the twinkling of the stars, caused
in this way; for before entering our atmosphere their light is perfectly
steady. Moreover, everyone must have observed that the amount of
twinkling varies greatly. At times it is unusually intense, and at
others the stars seem wonderfully still. Now, although the planets,
being near enough to show a disk visible through a telescope, do not
seem to twinkle, the same thing in fact occurs. The light is deflected,
and the shaking makes it very difficult to see the smaller markings.
Imagine trying to make out the detail on an elaborately decorated plate
held up by a man with a palsied hand. The plate would be seen easily,
but for the detail one would wish it held in a steadier grasp, and for
observing the planets this corresponds to a steadier atmosphere.
Percival’s own account of the reason for his expedition of 1894 to
observe the planet Mars, why he selected Flagstaff as the site, what he
did there and how the plan developed into the permanent observatory that
bears his name were told in what was intended to be an introduction to
the first volume of the Annals of the Observatory. Perhaps owing to the
author’s illness in the last years of the century this statement was
mislaid and was not found until February 22, 1901. It is here printed in
full.
Annals of the Lowell Observatory
INTRODUCTION
In the summer of 1877 occurred an event which was to mark a new
departure in astronomy,—the detection by Schiaparelli of the so-called
canals of the planet Mars. The detection of these markings has led to
the turning over of an entirely new page in cosmogony.
Schiaparelli’s discovery shared the fate of all important astronomical
advances,—even Newton’s theory of gravitation was duly combatted in its
day,—it, and still more the possibilities with which it was fraught,
distanced the comprehension of its time. In consequence, partly from
general disbelief, partly from special difficulty, no notable addition
was made to Schiaparelli’s own work until 1892, when Professor W. H.
Pickering attacked the planet at the Boyden Station of the Harvard
Observatory at Arequipa, Peru, and made the next addition to our
knowledge of our neighbor world.
Intrinsically important as was Pickering’s work, it was even more
important extrinsically. Schiaparelli’s discoveries were due solely to
the genius of the man,—his insight, not his eyesight, for at the
telescope eyes differ surprisingly little, brains surprisingly much;
Pickering’s brought into coöperation a practically new instrument, the
air itself. For at the same time with his specific advance came a
general one,—the realization of the supreme importance of atmosphere in
astronomical research. To the Harvard Observatory is due the first
really far-reaching move in this direction, and to Professor W. H.
Pickering of that observatory the first fruits in carrying it out.
It was at this stage in our knowledge of the possibilities in planetary
work and of the means to that end, in the winter of 1893-94, that the
writer determined to make an expedition which included the putting up of
an observatory for the primary purpose of studying, under the best
procurable conditions, the planet Mars at his then coming opposition,—an
opposition at which the planet, though not quite so close to us as in
1892, would be better placed for northern observers. In this expedition
he associated with himself Prof. W. H. Pickering and Mr. A. E. Douglass.
The writer had two objects in view:
1st, the determination of the physical condition of the planets of our
solar system, primarily Mars;
2d, the determination of the conditions conducive to the best
astronomical observations.
How vital was the inter-connection of the two was demonstrated by the
results.
Important as atmosphere is to any astronomical investigation, it is
all-important to the study of the planets. To get, therefore, within the
limits of the United States—limits at the time for several reasons
advisable—as steady air as possible, Prof. W. H. Pickering, who had
already had experience of Southern California as well as of Arequipa,
Peru, proposed Arizona as the most promising spot. Accordingly, Mr. A.
E. Douglass left Boston in March, 1894, with a six-inch Clark refractor
belonging to the writer, to make a test of the seeing throughout the
Territory. From his report, Flagstaff was selected for the observatory
site.
Flagstaff, then a town of eight hundred inhabitants, lies on the line of
the Atlantic and Pacific Railroad, in the centre of the great plateau of
northern Arizona, half way across the Territory from east to west, and
two fifths way down from north to south. This plateau, whose mean
elevation is between 6000 and 7000 feet, is a great pine oasis a hundred
miles or more in diameter, rising some 3000 feet from out the Arizona
desert. It culminates in the mass known as the San Francisco Peaks, ten
miles north of Flagstaff, whose highest summit rises 12,872 feet above
the level of the sea.[9]
The spot chosen was the eastern edge of the mesa (table-land) to the
west of Flagstaff. The site lay open to the east and south, and was
shielded on the north by the San Francisco Peaks. The distance from the
observatory to Mt. Agassiz, the most conspicuous of the Peaks from the
Flagstaff side, was about eight miles and three fifths in an air-line,
and the distance to the town about a mile and a quarter. As soon as the
site was selected, the town very kindly deeded to the observatory a
piece of land and built a road up to it.
The observatory stood 350 feet above the town, and 7250 feet above the
level of the sea, in latitude 35° 11′ north and longitude 111° 40′ west.
Prof. W. H. Pickering, to whose skill and ability was chiefly due the
successful setting up of the observatory, suggested arrangements with
Brashear for the use of an eighteen-inch refractor which Brashear had
recently constructed,—the largest glass to be had at the
time,—arrangements which were accordingly made. He then devised and
superintended the construction of a dome intended to be of a temporary
character, which worked admirably. The upper part of it was made in
sections in Cambridgeport, Mass., and then shipped West, the lower part
being constructed according to his specifications on the spot, under the
superintendence of Mr. Douglass.
The telescope was supported on one of the Clark mountings. The
bed-plate, clock-work, and a twelve-inch telescope were leased of the
Harvard College Observatory, and the mounting then altered by Alvan
Clark & Sons to carry both the twelve and the eighteen-inch telescopes.
Six weeks from the time ground was broken, on April 23, 1894, regular
observations with the eighteen-inch were begun.
The results of the year’s work surpassed anticipation. Details invisible
at the average observatory were presented at times with copper-plate
distinctness, and, what is as vital, the markings were seen hour after
hour, day after day, month after month. First sight; then system; and
the one of these factors was as fundamental to the results as the other.
Systematic work, first made possible and then properly performed, was
the open sesame to that most difficult branch of astronomical
observations, the study of our nearest neighbors in the universe.
The chief results obtained were:—
1st, the detection of the physical characteristics of the planet Mars to
a degree of completeness sufficient to permit of the forming of a
general theory of its condition, revealing beyond reasonable doubt first
its general habitability, and second its particular habitation at the
present moment by some form of local intelligence;
2d, corroboration and extension by Professor Pickering of his
discoveries at Arequipa with regard to the forms of Jupiter’s
Satellites;[10]
3d, the discovery and study by Mr. Douglass of the atmospheric causes
upon which good seeing depends.
It is of the observations connected with the first of these that the
present volume of the Annals alone treats.
As the publication of this volume has been so long delayed, it seems
fitting to add here a brief continuation of the history of the
observatory to the present time.
The results of the expedition in 1894, in the detection of planetary
detail, turned out to be so important an advance upon what had
previously been accomplished that the writer decided to form of the
temporary expedition a permanent observatory. Accordingly, he had Alvan
Clark & Sons make him a twenty-four-inch refractor, which fate decided
should be their last large glass; the Yerkes glass, although not yet in
operation at the time this goes to press, having been finished at nearly
the time his was begun. The glass received from Mantois happened to be
singularly flawless and its working the same. It was made twenty-four
inches in clear aperture, and of a focal length of thirty-one feet.
Alvan G. Clark accompanied the writer to Flagstaff and put the glass in
place himself.
The mounting for the telescope was likewise made by the Clarks. Rigidity
was the prime essential, in order to secure as stable an image as
possible, and this has been admirably carried out, the mounting being
the heaviest and most stable for a glass of its size yet made.
In July, 1896, Dr. T. J. J. See joined the observatory, to continue
there the line of research for which he was already well known—the study
of the double stars. This added to the two initial objects of the
observatory a third,—
3d, the study of double-star systems, including a complete catalogue of
those in the southern heavens.
During the summer and autumn of 1896 the importance of good atmosphere
was further demonstrated in an interesting and somewhat surprising
quarter. The air by day was found to be as practicable as that by night.
While Mars was being studied by night, the study of Venus and Mercury
was taken up during the daytime systematically, and the results proved
as significant as had been those on Mars. Instead of the vague diffused
patches hitherto commonly recorded, both planets’ surfaces turned out to
be diversified by markings of so distinct a character as not only to
disclose their rotation periods but to furnish the fundamental facts of
the physical conditions of their surfaces. We know now more about
Mercury and Venus than we previously knew of Mars.
As the winter in Flagstaff is not so good as the summer, it was thought
well to try Mexico during that season of the year. Accordingly, a new
dome was made; the telescope was taken down; and dome, mounting, and
glasses were carried to Mexico and set up for the winter at Tacubaya, a
suburb of the City of Mexico, at an elevation of 7500 feet. There the
observatory received every kindness at the hands of the President, the
Government, and the National Observatory.
Observations at Mexico fully corroborated those at Flagstaff with regard
to both Mars, Mercury and Venus, and enabled Mr. Douglass to make the
first full determination of the markings on Jupiter’s third and fourth
satellites, thus fixing their rotation periods.
Dr. See in the mean time, who while at Flagstaff had discovered a very
large number of new doubles, in Mexico added to his list;...
With the spring the observatory was shipped back again to Flagstaff.
Of the particular results in planetary work obtained, several papers
have been published in various astronomical journals, while of them
subsequent volumes of the Annals will speak in detail. In the meantime
two general conclusions to which they have led the writer may, as
possessing future interest, fittingly be mentioned here:
1st, that the physical condition of the various members of our solar
system appears to be such as evolution from a primal nebula would
demand;
2d, that what we call life is an inevitable detail of cosmic evolution,
as inherent a property of matter from an eventual standpoint as
gravitation itself is from an instant one: as a primal nebula or
meteoric swarm, actuated by purely natural laws, evolves a system of
bodies, so each body under the same laws, conditioned only by size and
position, inevitably evolves upon itself organic forms.
The reasons for the first of these conclusions have sprung directly from
the writer’s study of the several members of our own solar system; his
reason for the second, upon the further facts,—
1st, that where the physical conditions upon these bodies point to the
apparent possibility of life, we find apparent signs of life;
2d, where they do not, we find none.
This implies that, however much its detail may vary, life is essentially
the same everywhere, since we can reason apparently correctly as to its
presence or absence, a result which is in striking accord with the
spectroscopic evidence of a practical identity of material.
Evidently the expedition to observe Mars was undertaken quite suddenly,
but if it was to be made at all it must be done quickly. Anyone, however
unfamiliar with astronomy, will perceive that two planets revolving
about the sun in independent orbits will be nearest together when they
are on the same side of the sun and farthest apart when on opposite
sides of it, and that the difference is especially great if, as in the
case of the earth and Mars, their orbits are not far apart, for when on
the same side the separation is only the difference of their distances
from the sun, and when on opposite sides it is the sum of those
distances. Moreover, Mars being outside of the Earth its whole face is
seen in the full light of the sun when both bodies are on the same side
of it. Now such a condition, called opposition, was to occur in the
summer after Percival’s return from Japan, and therefore there was no
time to spare in getting an observatory ready for use.
From the experience of others elsewhere, Percival was convinced that the
most favorable atmospheric situations would lie in one of the two desert
bands that encircle a great part of the Earth, north and south of the
equator, caused by the sucking up of moisture by the trade winds; and
that a mountain, with the currents of air running up and down it, did
not offer so steady an atmosphere as a high table-land. The height is
important because the amount of atmosphere through which the light
travels is much less than at sea level. He was aware that the best
position of this kind might well be found in some foreign country; but
again there was no time to search for it, or indeed to build an
observatory far away, if it must be equipped by the early summer. The
fairly dry and high plateau of northern Arizona seemed, therefore, to
offer the best chance of a favorable site for this immediate and
temporary expedition.
With the aid of suggestions by Professor William H. Pickering, who knew
what was needed in observing Mars, he sent Mr. Douglass, with the
six-inch telescope brought back from Japan, to Arizona to inspect the
astronomic steadiness of the atmosphere. The instructions, apparently
drawn up by Professor Pickering, were dated February 28th, directing him
to observe on two nights each at Tombstone, Tucson and Phoenix; and
Percival, keeping in constant touch with Mr. Douglass by letter and
telegraph, added among other places Flagstaff. This was shortly followed
by instructions about constructing the circular vertical part of the
dome for the observatory by local contract as soon as the site was
selected, while the spherical part above, which was to be of parallel
arches covered with wire netting and canvas, was being made in the East
and to be shipped shortly. Meanwhile the pier was being built by Alvan
Clark & Sons (who had made most of the large telescopes in this country)
and the mounting for both the eighteen-inch and the twelve-inch
telescope thereon, balancing each other. Mr. Douglass was to report
constantly; and in April Percival wrote him to take a photograph of the
site of the observatory “now,” then every day as the work progressed,
and have the negatives developed, a blue print made of each as speedily
as possible and sent East. All this is stated here to show the speed,
and at the same time the careful thought, with which the work was done.
Percival and his colleagues came as near as possible to carrying out the
principle, “when you have made up your mind that a thing must be done,
and done quickly, do it yesterday.”
In fact Percival did not select any of the three places first examined,
but on consideration of Mr. Douglass’ reports preferred Flagstaff; and
his choice has been abundantly confirmed by the pioneering problems
undertaken there, and by the fact that this site was retained for the
later permanent Observatory. Everyone, indeed, deserves much credit for
the rapid work done at such a distance from principals busy with the
preparation of the instruments. It was characteristic of Percival that
he got the very best out of those who worked with and under him.
Although the closest point of the opposition did not occur until the
autumn, the two planets, travelling in the same direction, were near
enough together for fair observation some months earlier; and on May
28th, arriving at Flagstaff, Percival writes to his mother: “Here on the
day. Telescope ready for use tonight for its Arizonian virgin view....
After lunch all to the observatory where carpenters were giving their
finishing touches.... Today has been cloudy but now shows signs of a
beautiful night and so, not to bed, but to post and then to gaze.” The
sky was not clear that night, for an unprecedented rain came and lasted
several days, falling through the still uncanvased dome on Professor
Pickering and Percival, who had been lured by a “fairing” sky into
camping out there in the evening to be on time for the early rising
Mars. But it was not long before the weather cleared and the strenuous
work began. As the observatory was a mile and a half from the hotel in
the town, and uphill, it was uncomfortable to arrive there at three
o’clock in the morning, the hour when at that season Mars came in sight.
So in the summer a cottage was built hard by the dome, where they could
sleep and get their meals.
The observations were, of course, continuous throughout the rest of the
year; and except for two trips East on business, one for a few weeks at
the end of June, another in September, and a few days in Los Angeles,
Percival was there all the time. As usual he worked furiously; for
beside observing most of the night he spent much of the day writing
reports and papers, making drawings for publication in scientific and
other periodicals, and investigating collateral questions that bore upon
their significance; and while he had computers for mechanical detail, he
and his colleagues had to prepare and supervise their work. To his
mother he wrote, as a rule, every day; and in some of these letters he
gave an account of his time. On September 2nd, he writes of being up the
greater part of the night, and naturally perpetually sleepy. “But the
number of canals increases encouragingly—in the Lake of the Sun region
we have seen nearly all Schiaparelli’s and about as many more.” On
October 10th: “Observed the better part of last night, after being
welcomed by everybody—and have been as a busy as a beaver today, writing
an article, drawing for ditto etc, etc.”; and, two days later, “Chock
full of work; scrabbling each day for the post—proof etc. Mr. Douglass
is now on the hill observing Mercury. We all dine there at seven. Then I
take Mars and at 3 A.M. Professor Pickering, Jupiter. So you see none of
the planets are neglected.”
In one of these letters he encloses a clipping from a San Francisco
newspaper satirizing Professor Holden for saying that the canals of Mars
reported at Flagstaff were not confirmed by observations at Mount
Hamilton. Denial or doubt that he had really seen what—after many
observations confirmed by those of his colleagues—he reported as seen
always vexed Percival, and naturally so. Yet they were not uncommon and
sometimes attributed to defective vision. He was well aware that while a
belief that a thing exists may make one think he has seen it when he has
not, yet it is also true that one person perfectly familiar with an
object sought will find it when another, unacquainted with its precise
appearance, will miss it altogether. Everyone knows that people in the
habit of looking for four-leaved clovers are constantly picking them
while others never see them; or that a skilled archaeologist finds
arrowheads with much greater facility than a tyro, who will, however,
improve rapidly with a little experience; and all this is especially
true of things near the very limit of visibility. Gradually more and
more observers began to see the finer markings and the canals on Mars,
until finally the question of their existence was set at rest when it
became possible to photograph them.
But in spite of work and vexation the life was far from dull, for the
observatory was as hospitable as its limited quarters would allow.
Visitors were attracted by its growing reputation, and on August 25th he
writes: “Just as we were plodding up there last evening in the dark we
heard a carriage-full of folk coming down. We suspected what they had
been after and were not surprised when they challenged us with ‘Are you
observatory people?’ It seems they were, as they informed us
pathetically, people from the East and had gone up to look through the
glass, if they might, before taking the train at 12.30 that night. Of
course we could not resist their appeals and so, though we had thought
to turn in betimes because of early observations in the morning,
entertained these angels—half of them were women—on ‘just like diamonds’
as they said of the stars. The out-of-focus views pleased them the
most—as turns out to be the case generally. This morning when I went to
take Pickering’s place I found another angel in the shape of a Colorado
man, out here for his health, in the dome with Pickering—a nice fellow
he turned out. It was then 4 h. 8 m. o’clock in the morning,—a matutinal
hour for a man to trudge a mile and a half on no breakfast up to an
observatory on a hill—That shows real astronomical interest. He was
rewarded gastronomically with some coffee of my brewing, all three of us
breakfasting standing by the platform.”
There were occasional picnics and trips to the cave dwellings, the Grand
Cañon, the petrified forest and other sights. Moreover, Percival greatly
enjoyed the scenery about Flagstaff, and took an interest in the people
of the town, although well aware of inexperience in some matters. On
October 13th he says: “There was a grand republican rally last night and
the young Flagstaff band that is learning to play in tune serenaded the
speaker of the occasion under the hotel windows in fine style. When you
knew the air beforehand you could follow it with enthusiasm.”