Where the telescope should be set up was not yet decided; for it will be remembered that he wanted to make his observations in any accessible place in the world where the clearest, and especially the steadiest, atmosphere would be found. As already explained, he believed this lay in one of the two great desert belts that encircle the Earth north and south of the equator; and, for practical purposes, that meant Arizona, Mexico and South America in the Western Hemisphere, and the Sahara in the Eastern. Mr. Douglass had therefore been sent—probably with the faithful 6-inch telescope—to Mexico and South America, while Percival proposed to examine the Sahara himself.
The year following his return to Boston, at the end of November, 1894, was filled with the arrangements for his new telescope and apparatus, and in writing the book on Mars. At this time he lived at 11 West Cedar Street, the little house he had bought some time before; for it was characteristic that, while lavishing whatever was needed on his observatory, he was modest in his expenditure on himself. By the end of the year his book was published, his work for the coming observatory was done, and he went to Europe; but his Mother had died in March, and the daily stream of loving letters, which told about himself, had ceased to flow.
On December 10, 1895, he sailed on theSpreewith Alvan G. Clark, the last surviving brother of the telescope-making family. The voyage, though very rough at times, was uneventful, until as they were entering the Solent the vessel struck, and stuck fast, on Warden’s Ledge, just inside the Needles. “Fault of the pilot” Percival recorded, “aged 73 and bordering on imbecility.” With all his travels about and around the world this is the nearest he ever came to shipwreck; nor was it for him very near, for since the ship could not get herself clear tugs came down the next day and took off the passengers, who were landed at Southampton andwent up to London. Two days later he was in Paris, and for nearly three weeks he and Clark saw astronomical friends,—among others having to lunch and dinner Edouard Mantois, the great glass manufacturer who had cast the new 24-inch refractor for his telescope. Percival enjoyed a most interesting dinner at the house of Flammarion, the astronomer and novelist, who was devoted to Mars and had followed his work at Flagstaff. As he wrote to his Father—“There were fourteen of us, and all that could sat in chairs of the zodiac, under a ceiling of a pale blue sky, appropriately dotted with fleecy clouds, and indeed most prettily painted. Flammarion is nothing if not astronomical. His whole apartment, which is itself au cinquieme, blossoms with such decoration.
“At the dinner I made the acquaintance of Miss Klumpke of the Paris Observatory, who has just translated my last article for the Bulletin of the Société Astronomique.”
In fact before he left Paris for Africa he gave a talk to that society, on his observations of Mars. At Marseilles, meeting his old friend, Ralph Curtis, they crossed to Algiers and made excursions to Boghari and Biskra to test the atmosphere on the border of the Sahara. Not finding this satisfactory, he organized a small private caravan of his own for a journey of a few days into the desert, taking the telescope—doubtless the faithful six-inch—on a mule. His going off by himself across country seems to have worried his companions for fear he would lose his way; but he always turned up in the afternoon, and in time to observe when the stars came out. Curiously enough, he found that although the air was very clear they twinkled badly, so that while the atmosphere was transparent it was distinctly unsteady, for his purpose a verygrave defect which excluded North Africa from the possible sites for his observatory. Satisfied on this point, he left Algiers in February.
From Marseilles he took the opportunity to visit Schiaparelli, to whom he owed so much of the incentive to study Mars, and found him at his observatory in Brera near Milan. With him he compared observations, much to his own satisfaction. The veteran looked middle-aged, but did not expect to make more discoveries, and said that at the preceding opposition the weather had been so bad that he saw almost nothing. So his mantle had definitely fallen on Percival when he began his observations at Flagstaff the year before.
Leaving Milan he started to visit Leo Brenner, who was also interested in Mars, and had his observatory at Lussinpiccolo, a rather inaccessible spot on the eastern coast of the Adriatic. In getting there he was much delayed by a heavy storm, and beguiled the time by working out a mathematical theory of the tides. Finally, he decided to go by rail to Pola, and thence by boat to Lussinpiccolo, where Brenner met him, insisting that he should stay with them. They proved most hospitable and kind, but he was not favorably impressed by the observatory or its work; and after a stay of a few days he returned through Cannes, Paris and London, sailing for America on March 19th, to land in New York on the 28th.
Meanwhile, the work on the lens and its apparatus had been finished; but it could not be set up until he was there, and arriving at the end of March there was no time to spare. For although the opposition of Mars did not occur until December 10th the planets would then be far past their nearest point, and there was much to see months before. In fact he, with Clark, arrived at Flagstaff shortly after themiddle of July, and proceeded at once to put the glass into the telescope—no small difficulty, for the tube was so tight a fit in the dome which had housed the Brashear telescope that the lens had to be hoisted up and let into it through the shutter opening,—“quite a job,” as he wrote, “for so delicate and yet heavy a thing as a 24-inch lens.” However, it was successfully done, and the next morning at half past two observing began, and thereafter the dome knew no rest.[13]
In the letter last quoted he says that he has “taken a brand new house, finished indeed after I arrived, a little gem of a thing.” Before long he had three houses on the hill there, and began that succession of charming hospitalities ending only with his life. Friends like Professor and Mrs. Barrett Wendell and Professor Charles S. Sargent visited there, while Professor Edward S. Morse and George R. Agassiz, who were interested in his investigations, paid him long visits; and since Flagstaff was on the direct road to Southern California, a paradise becoming more and more fashionable, many others stopped off on the way to see him and his observatory, whom he was always delighted to entertain, for he had an unusual capacity for doing so without interrupting the course of his work. Then there were excursions to the cave dwellings, the petrified forest, and other places of interest in the neighborhood, for he loved the country about him, and took pleasure in showing it to others. Sometimes these trips were unusual. “We all rode,” he writes to a friend, “twelve miles out into the forest on the cow-catcher of a logging train, visited there a hole in the ground containing, if you crawl down through the chinks in the rocks several hundred feet, athing we were not accoutered to do, real ice in midsummer; came back on the cow-catcher; and immensely enjoyed the jaunt. The acmes of excitement were the meeting of cattle on the track who showed much more unconcern of us than we of them. Indeed it was usually necessary for the fireman to get down and shoo them off.... Nevertheless we saw a real bull fight in a pretty little valley far from men where Greek met Greek for the possession of the herd. The two champions toed the line with great effect.” Nor did his interest in literature abate, for a few weeks later he wrote to the same correspondent: “Send me, an’ you love me, the best Chaucer at my expense.”
Meanwhile the observations of Mars and the other planets went on with success, and he was naturally gratified when his telescope revealed something that others had failed to find, such as Professor “See’s detection of the companion to Sirius which astronomers have been looking for in vain since its immersion some years ago in the rays of its primary due to its place in its orbit. The Lick hunted for it unsuccessfully last year”; the last remark being pointed by the fact that this rival had again been casting doubt upon his discoveries on Mars.
He observed without a break all summer and autumn, but aware that the atmosphere at Flagstaff was not so good in the winter, he decided to try that of Mexico, and thither he went in December taking the 24-inch telescope. Before the dome therefor was built he saw well with the six-inch; but for the larger glass the results were on the whole disappointing. Yet the observations in Mexico were by no means unproductive. To his father he writes: “In addition to all that I have told you before, Mr. Douglass has just made some interestingstudies of Jupiter’s satellites, seeing them even better than we did at Flagstaff, and detecting markings on them so well that they promise to give the rotation periods and so lead to another pregnant chapter in tidal evolution.” And in another letter to him: “Mercury, Venus, Mars, and Jupiter’s satellites have all revealed new things about themselves. I intend to embody all of these things some day in a series of volumes on the planets.” Meanwhile, as during the observations of two years before, he was sending papers to various scientific journals, American and foreign, about results obtained on Mars, Mercury and Venus; and about this time Sir Robert Hart asked through Professor Headland permission to translate “Mars” into Chinese. One may add that the first volume of the “Annals of the Lowell Observatory” appeared that year (1897), the next in 1900.
But his personal hopes of contributing further to science, or diffusing the knowledge learned, were destined to be sadly postponed. In the spring he left Mexico, and the telescope was returned to Flagstaff in May; but although he could stand observing day and night without sufficient sleep while stimulated by the quest, the long strain proved too much, and he came back to Boston nervously shattered. Such a condition is not infrequent with scholars who work at high speed, and although the diagnosis is simple the treatment is uncertain. The physicians put him to bed for a month in his father’s house in Brookline, a measure that he always thought a mistake, believing that he would not have collapsed so completely under a different regimen. The progress everyone knows who has seen it, a very slow regaining of strength, with ups and downs, and after much discouragement—in his case about three years—a return to normal health.
After the doctors let him up from bed he sought rest in divers places, but the progress was slow and uneven, as it must be in such cases. Naturally letters at this period are few, short and far between. Only two, written to his father, appear to have been preserved, one from Bermuda, January 22, 1898:
“Dear Father:I enclose what I think you will like to see, a copy made for you of a letter just received.Festina lenteis nature’s motto for me, and I try to makenulla vestigia retrorsum.Affectionately your sonPercival”
“Dear Father:
I enclose what I think you will like to see, a copy made for you of a letter just received.Festina lenteis nature’s motto for me, and I try to makenulla vestigia retrorsum.
Affectionately your sonPercival”
The copy enclosed is evidently of the letter from Professor Headland conveying Sir Robert Hart’s request to translate “Mars” into Chinese. The other letter is on January 17, 1899, with no place—date, and it says: “Was much better; now can’t sleep well. So it wags.”
A year later, although not yet recovered, he was so much improved as to plan with Professor Todd of Amherst an expedition to Tripoli to observe a total eclipse of the sun. They took a 24-inch lens, from the observatory at Amherst, with a very light tube for transportation in four joints that would slip inside one another, and a device for photographing the solar corona; the lens of the telescope being the largest yet used in such an expedition. Sending the apparatus by freight, they themselves sailed on the German SteamshipSt. Paulfrom New York on January 17, 1900. He had regained his humor, if nothing else, for he heads his private journal of this exploit: “An Eclipse trip to Tripoli being the sequel to The Valet and the Valetudinarian”—not that he ever wrote anything under this last title, but it was a reference to what he had been through in the preceding two and a half years—and after inserting two flamboyant newspaper clippings, for which he was not responsible, he writes: “Further notices there were of which no notice need be taken; literary and professional murders all, of various degrees of atrocity.”
After a few days in London, where he exchanged comments on the spectrum of Mars with Sir William Huggins, he passed on to Paris, and then Marseilles and Costabella where his widowed sister, Katharine Roosevelt, was staying. The eclipse was not to occur until the end of May, but there was much to be done in setting up the instruments, at which he was not needed; so as he saw his sister off for Italy he also bade good-bye for a time to Professor Todd, who left him to look up the telescopic apparatus and get it in place at Tripoli, while he stayed to recuperate for three months on the Riviera.
Here he found William James who, with his wife, was on a like quest to recruit from a similar case of neurasthenia, and at the same time to prepare his Gifford lectures. To his father Percival wrote on April 7: “Professor William James is living here now and we see each other all the time. He is pleased at having just been elected a corresponding member of the Academy of Sciences of Berlin, more for his children’s sake than his own. This when he thought he should never be able to work again, and he wanted them to feel that their father had done something. Now, however, he is stronger and polishes off some Gifford lectures daily, a bit of it.” They saw much of each other, being highly sympathetic physically and intellectually. Like himself, James had recovered, or not lost, his sense of humor, and quoted a remark he had heard “that ethics was a tardy consolation for the sins one had neglected to commit.” And Percival was impressed by his saying that he “considered Darwin’s greatness due to his great detail as increasing the probabilities; showing again how mere detail, mere bulk impresses, though probability be not furthered a bit.” The last part of the sentence may be Percival’s own conclusion rather than that of James,but it had clearly a bearing on his own minute study of the phenomena of Mars.
On the Riviera he made a number of pleasant acquaintances and he was well enough to enjoy seeing people; but, although he was writing a memoir for the American Academy on Venus, he was not yet up to really hard work. After trying in vain to think out mechanical explanations for the small ellipticity in the orbits of the planetary satellites he gave it up, and noted: “I actually am taking pleasure in chronicling this small beer (his solitary walks); pure thought proves so thorny to press.” On April 3d he writes to his father: “I am trying to catch up with you and grandfatherSed longo intervalloso as to solace my solitary walks with fixed acquaintances.” Both of these forebears had been interested in botany. In fact he walked much alone, studying the trees, shrubs and insects, and he writes: “I can converse with plants because they don’t talk back, nor demand attention but accept it.”
The time for the eclipse was drawing near, so after going to Florence to spend a few days more with his sister, he sailed from Genoa on May 16; trans-shipped at Naples, and going ashore in Sicily and Malta while the steamer was in port, reached Tripoli on May 24th. Travelling to out-of-the-way places in the Mediterranean was not a rapid process, and Tripoli then belonged to Turkey; but he found everything prepared by Professor Todd in the grounds of the American Consulate, and, fortunately, when the eclipse occurred four days later the sky was clear and everything went well. He was amused by the comments of the ignorant. “The Arabs,” he wrote in his private journal, “the common folk, told their friends (beforehand) that the Christians lied, and when theaffair came off, that they had no business to know being infidel.” But he was as always interested in their ways and habits, mousing about the town with our consul and others, learning about the Turkish troops, and the Tuaureg camel drivers, inspecting a bakery, a macaroni factory, threshing and the weekly fair.
On June 3rd they sailed by an Italian steamer for Malta, but he left it at Tunis to go to the ruins of Carthage, which impressed him greatly; catching the boat again at Biserta, and at Malta trans-shipping again for Marseilles, he made his way to Paris. There the exhibition was open, and among other things he found his exhibit from Flagstaff, “poor waif, in a corner of the Palais de l’Optique and in another place stood confronted by four of my own drawings of Mars, unlabelled, unsubscribed. Felt badly for the poor orphans.” He did not stay long, but went to England, and after spending a few days at the country house of some friends he had made on the Riviera, he sailed for home on July 4th. Shortly before leaving he had received telegrams telling of his father’s unexpected death under an operation, cutting another link with his earlier life.
As yet not well enough to resume his work, he hired a farm house at Chocorua, and settled there on August 3rd for the rest of the summer. He enjoyed seeing the friends and neighbors who spent their vacations there; but, like some other men of science incapacitated by illness, he turned his attention to a field other than his own. As on the Riviera, this was flowers, butterflies, and especially trees; but he studied them more systematically, and with fuller notes. In October he gives a list, covering more than three pages, of the trees and shrubs in the woods, fields and swamps abouthim in the order of their abundance. This interest he kept up in later years at Flagstaff, corresponding with Professor Charles S. Sargent, the Director of the Arnold Arboretum, and sending him specimens of rare or unknown varieties, some of which were named after him. So highly, indeed, did Sargent rate him that after Percival’s death he wrote a memoir of him inRhodora,[14]which it is well to transcribe in full:
“That Percival Lowell took an active interest in trees was probably not known to many persons, for he published only one botanical paper and he had no botanical associates except in this Arboretum. It is not surprising that a man with his active and inquiring mind brought up in New England should, when he found himself in Arizona, want to know something of the strange plants which grew everywhere about him and which were so entirely unlike the plants which he had known as a boy in Massachusetts, and later in Japan and Korea. The love of plants, too, was in his blood and only needed the opportunity of this new field to make itself felt.“Percival Lowell’s great great grandfather, John Lowell, was one of the original members of the Massachusetts Society for Promoting Agriculture and its second President, serving from 1796 until his death in 1802. He is less well known for his connection with rural affairs than his son John Lowell, spoken of generally in his day as “the Norfolk Farmer,” and a generous and successful promoter of scientific agriculture and horticulture in Massachusetts, whom Daniel Webster called “the uniform friend of all sorts of rural economy.” The second John Lowell became a member of the Agricultural Society in 1816 and served from the time of his election until 1830 as its Corresponding Secretary, and as one of the editors of its publication,The Massachusetts Agricultural Repository and Journal. During these years articles by him on agriculture, horticulture and forestry are found in almost everynumber. In volume v. published in 1819 there is an important paper by John Lowell on “The Gradual Diminution of the Forests of Massachusetts, and the importance of early attention to some effectual remedy, with extracts from the work of M. Michaux on the Forest Trees of North America.” Volume vii. contains articles from his pen on “Some slight notice of the Larch tree (Pinus Larix), known in various parts of the country under the several names of Juniper, Hackmatack, and Larch”; on “Fruit Trees,” signed by the Norfolk Gardener, and on “Raising the Oak from the Acorn and the best way of doing it.” The last volume of this publication which appeared in 1832, when he was seventy-one years old, contains an article by John Lowell on “The Extraordinary Destruction of the last Year’s Wood in Forest Trees and the probable Causes of it”; and on “Live Hedges for New England.” The second John Lowell was active in establishing and maintaining the Botanic Garden of Harvard College and was one of the original members of the Massachusetts Horticultural Society. To the first annual festival of the Horticultural Society held in the Exchange Coffee House on State Street, September 19, 1829, he sent from his greenhouses in Roxbury Orange-trees covered with flowers and fruit and a bunch of grapes weighing three pounds.“John Amory Lowell, the son of the second John Lowell and the grandfather of Percival Lowell, was deeply interested in botany and in 1845, thirty years after his graduation from Harvard College, began the collection of an herbarium and botanical library with the purpose of devoting himself seriously to the study of plants. He had made valuable collections and a large botanical library when the financial troubles of 1857 forced him to abandon botany and devote himself again to business affairs. His most valuable books were given by him to his friend Asa Gray and now form an important part of the library of the Gray Herbarium. His herbarium and his other botanical books were given to the Boston Society of Natural History. John Amory Lowell, like his father and grandfather, was a member of the Massachusetts Society for Promoting Agriculture. He was succeeded by his son John Lowell, who in turn was succeeded by his son, anotherJohn Lowell, who of the fifth generation in direct descent from its second president is now a Trustee of this Society.“Percival Lowell’s love of plants certainly came to him naturally. I first met him in the Arboretum many years ago examining the collection of Asiatic Viburnums in which he was interested at that time, but it was not until 1910 that he began to send specimens to the Arboretum, including that of an Oak which he had found growing near his observatory and which so far as it is possible to judge is an undescribed species. Interest in this Oak led him to look for other individuals and to extend his botanical explorations. During these he visited Oak Creek Canyon, a deep cut with precipitous sides in the Colorado plateau which heads about twenty miles south of Flagstaff and carries in its bottom a small stream which finally finds its way into the Verde northwest and not far from Camp Verde. Lowell appears to have been the first botanist who visited the upper part, at least, of this canyon where he found a number of interesting plants, notablyPlatanus WrightiiandQuercus arizonica, which before his explorations were not known to extend into the United States from Mexico beyond the canyons of the mountain ranges of southern Arizona and New Mexico. In Oak Creek Canyon Lowell found a new Ash-tree somewhat intermediate betweenFraxinus quadrangulataof the east andF. anomalaof our southwestern deserts which will bear his name. Later Lowell explored Sycamore Canyon which is west of Oak Creek Canyon and larger and deeper than Oak Creek Canyon and, like it, cuts through the Colorado plateau and finally reaches the Verde near the mouth of Oak Creek.“Juniperus in several species abound on the Colorado plateau, and Lowell became deeply interested in these trees and was preparing to write a monograph of our southwestern species. His observations on the characters and altitudinal range of the different species, illustrated by abundant material, have been of great service to me.“Lowell’s only botanical paper, published in the May and June issues of theBulletin of the American Geographic Societyin 1909, is entitled “The Plateau of the San Francisco Peaks in its Effecton Tree Life.” In this paper, which is illustrated by photographs made by the author of all the important trees of the region, he discusses the altitudinal distribution of these trees, dividing his region into five zones which he illustrates by a number of charts showing the distribution of vegetation in each. It contains, too, an important and interesting discussion of the influence on temperature and therefore on tree growth of the larger body of earth in a plateau as compared with a mountain peak where, on account of greater exposure, the earth cools more rapidly.[15]“A bundle of cuttings of what is probably a new species of Willow, to obtain which Lowell had made a long and hard journey, with his last letter and a photograph of the Willow, came only a few days before the telegram announcing his death. Botany therefore occupied his thoughts during his last days on earth.“The death of Percival Lowell is a severe loss to the Arboretum. He understood its purpose and sympathized with its efforts to increase knowledge. Few collectors of plants have shown greater enthusiasm or more imagination, and living as he did in what he has himself described as “one of the most interesting regions of the globe” there is every reason to believe that as a botanist Percival Lowell would have become famous.”
“That Percival Lowell took an active interest in trees was probably not known to many persons, for he published only one botanical paper and he had no botanical associates except in this Arboretum. It is not surprising that a man with his active and inquiring mind brought up in New England should, when he found himself in Arizona, want to know something of the strange plants which grew everywhere about him and which were so entirely unlike the plants which he had known as a boy in Massachusetts, and later in Japan and Korea. The love of plants, too, was in his blood and only needed the opportunity of this new field to make itself felt.
“Percival Lowell’s great great grandfather, John Lowell, was one of the original members of the Massachusetts Society for Promoting Agriculture and its second President, serving from 1796 until his death in 1802. He is less well known for his connection with rural affairs than his son John Lowell, spoken of generally in his day as “the Norfolk Farmer,” and a generous and successful promoter of scientific agriculture and horticulture in Massachusetts, whom Daniel Webster called “the uniform friend of all sorts of rural economy.” The second John Lowell became a member of the Agricultural Society in 1816 and served from the time of his election until 1830 as its Corresponding Secretary, and as one of the editors of its publication,The Massachusetts Agricultural Repository and Journal. During these years articles by him on agriculture, horticulture and forestry are found in almost everynumber. In volume v. published in 1819 there is an important paper by John Lowell on “The Gradual Diminution of the Forests of Massachusetts, and the importance of early attention to some effectual remedy, with extracts from the work of M. Michaux on the Forest Trees of North America.” Volume vii. contains articles from his pen on “Some slight notice of the Larch tree (Pinus Larix), known in various parts of the country under the several names of Juniper, Hackmatack, and Larch”; on “Fruit Trees,” signed by the Norfolk Gardener, and on “Raising the Oak from the Acorn and the best way of doing it.” The last volume of this publication which appeared in 1832, when he was seventy-one years old, contains an article by John Lowell on “The Extraordinary Destruction of the last Year’s Wood in Forest Trees and the probable Causes of it”; and on “Live Hedges for New England.” The second John Lowell was active in establishing and maintaining the Botanic Garden of Harvard College and was one of the original members of the Massachusetts Horticultural Society. To the first annual festival of the Horticultural Society held in the Exchange Coffee House on State Street, September 19, 1829, he sent from his greenhouses in Roxbury Orange-trees covered with flowers and fruit and a bunch of grapes weighing three pounds.
“John Amory Lowell, the son of the second John Lowell and the grandfather of Percival Lowell, was deeply interested in botany and in 1845, thirty years after his graduation from Harvard College, began the collection of an herbarium and botanical library with the purpose of devoting himself seriously to the study of plants. He had made valuable collections and a large botanical library when the financial troubles of 1857 forced him to abandon botany and devote himself again to business affairs. His most valuable books were given by him to his friend Asa Gray and now form an important part of the library of the Gray Herbarium. His herbarium and his other botanical books were given to the Boston Society of Natural History. John Amory Lowell, like his father and grandfather, was a member of the Massachusetts Society for Promoting Agriculture. He was succeeded by his son John Lowell, who in turn was succeeded by his son, anotherJohn Lowell, who of the fifth generation in direct descent from its second president is now a Trustee of this Society.
“Percival Lowell’s love of plants certainly came to him naturally. I first met him in the Arboretum many years ago examining the collection of Asiatic Viburnums in which he was interested at that time, but it was not until 1910 that he began to send specimens to the Arboretum, including that of an Oak which he had found growing near his observatory and which so far as it is possible to judge is an undescribed species. Interest in this Oak led him to look for other individuals and to extend his botanical explorations. During these he visited Oak Creek Canyon, a deep cut with precipitous sides in the Colorado plateau which heads about twenty miles south of Flagstaff and carries in its bottom a small stream which finally finds its way into the Verde northwest and not far from Camp Verde. Lowell appears to have been the first botanist who visited the upper part, at least, of this canyon where he found a number of interesting plants, notablyPlatanus WrightiiandQuercus arizonica, which before his explorations were not known to extend into the United States from Mexico beyond the canyons of the mountain ranges of southern Arizona and New Mexico. In Oak Creek Canyon Lowell found a new Ash-tree somewhat intermediate betweenFraxinus quadrangulataof the east andF. anomalaof our southwestern deserts which will bear his name. Later Lowell explored Sycamore Canyon which is west of Oak Creek Canyon and larger and deeper than Oak Creek Canyon and, like it, cuts through the Colorado plateau and finally reaches the Verde near the mouth of Oak Creek.
“Juniperus in several species abound on the Colorado plateau, and Lowell became deeply interested in these trees and was preparing to write a monograph of our southwestern species. His observations on the characters and altitudinal range of the different species, illustrated by abundant material, have been of great service to me.
“Lowell’s only botanical paper, published in the May and June issues of theBulletin of the American Geographic Societyin 1909, is entitled “The Plateau of the San Francisco Peaks in its Effecton Tree Life.” In this paper, which is illustrated by photographs made by the author of all the important trees of the region, he discusses the altitudinal distribution of these trees, dividing his region into five zones which he illustrates by a number of charts showing the distribution of vegetation in each. It contains, too, an important and interesting discussion of the influence on temperature and therefore on tree growth of the larger body of earth in a plateau as compared with a mountain peak where, on account of greater exposure, the earth cools more rapidly.[15]
“A bundle of cuttings of what is probably a new species of Willow, to obtain which Lowell had made a long and hard journey, with his last letter and a photograph of the Willow, came only a few days before the telegram announcing his death. Botany therefore occupied his thoughts during his last days on earth.
“The death of Percival Lowell is a severe loss to the Arboretum. He understood its purpose and sympathized with its efforts to increase knowledge. Few collectors of plants have shown greater enthusiasm or more imagination, and living as he did in what he has himself described as “one of the most interesting regions of the globe” there is every reason to believe that as a botanist Percival Lowell would have become famous.”
By the early spring of 1901 Percival was well over his illness, and fit to return to the Observatory for the oppositions of Mars in that year, in 1903 and in 1905. Shortly after he came back the services of Mr. Douglass came to an end, and he was fortunate in obtaining Dr. V. M. Slipher in 1901 and Mr. C. O. Lampland in the following year—two young men who were not only invaluable assistants to him, but during his lifetime, and ever since, have made distinguished contributions to science. Observing at all hours of the night was exacting work; and to anyone less enthusiastic, who did not see through the detail to its object, it might have been monotonous and wearisome. As he wrote himself, “Patient plodding is the road to results in science, and the shortest road in the end. Each year out here has seemed to me the best, which merely means that I hope I learn a little and that there is a vast deal to learn.” He felt strongly the need of diligence and strict impartiality in ascertaining the facts, and distinguished it sharply from the imagination to be used in interpreting them. In describing his delineation of the canals he says, “Each drawing, it should be remembered, was as nearly an instantaneous picture of the disk as possible. It covered only a few minutes of observation, and was made practically as if the observer had never seen the planet before. In other words, the man was sunk in themanner. Such mental effacement is as vital to good observation as mental assertion is afterward to pregnant reasoning. For a man should be a machine in collecting his data, a mind in coördinating them. To reverse the process, as is sometimes done, is not conducive to science.” But through all the exacting labor of the search he felt keenly the joy of discovery, comparing himself to the explorers of the Earth, and in the first chapter of “Mars and its Canals” he tells us of the pleasure of a winter night spent in the Observatory.
The oppositions in 1901, 1903 and 1905 were not so favorable as those of 1894 and 1906-1907, because Mars was not so near the Earth; the eccentricities in the orbits of the two planets causing them to pass each other when Mars was far from the Sun and therefore from the Earth whose eccentricity is less. Yet they had an advantage in the fact that, unlike the earlier occasions, the south pole was tipped away from the Earth, and the north pole was toward it, thus giving a good view of the northern polar cap, sub-arctic and higher temperate zones, which had not been visible before. Thus the seasonal changes could be observed in the opposite hemisphere,—not an inconsiderable gain, because the dark and light areas, that is, the natural vegetation and the deserts, are not equally distributed over the planet, for the dark ones occupy a much larger part of the southern, and the deserts of the northern, hemisphere. Moreover, the use of a larger lens and better atmosphere had shown that observations could be carried on profitably for a longer period before and after the actual opposition; until in 1905 it was possible to cover what had been left unobserved of the Martian year in the northern half of Mars.
No sooner was the third of these oppositions past than he wrote another book on the subject, with the title “Mars and its Canals”; and this in no sense a supplement to the earlier one, but an entirely new and independent presentation of the subject, covering the old ground and much more. He was enabled to do this because the copyright of the earlier work belonged to him. The later one was published by The Macmillan Company in December 1906, and dedicated to Schiaparelli. Like the earlier book, he wrote it by no means for astronomers alone, but for the interested public; and in the preface he tells why he did so: “To set forth science in a popular, that is in a generally understandable, form is as obligatory as to present it in a more technical manner. If men are to benefit by it, it must be expressed to their comprehension. To do this should be feasible for him who is master of his subject, and is both the best test of, and the best training to that post.... Nor is it so hard to make any well-grasped matter comprehensible to a man of good general intelligence as is commonly supposed. The whole object of science is to synthesize, and so simplify; and did we but know the uttermost of a subject we could make it singularly clear.” At the same time there was nothing in these writings of the nature of what is commonly called popularizing science. He expounded his subject in a strictly scientific way, but avoided unfamiliar technical terms if possible, and sought to raise his readers or audience to his level of thought, not to descend to theirs. Such statements for the public were very often preceded by technical ones in the Bulletins of the Observatory or elsewhere, and yet it cannot be doubted that the former tended to alienate some scientific scholars who were slow to admit his discoveries,and did not sympathize with his method of presenting them, or perhaps with the attractive style of the man of letters as well as of exact thought.
Still there are pitfalls in taking the public into one’s confidence; as he found in December 1900, when a telegram sent by the usual channels to the astronomical world, that the night before a projection had been observed on Mars that lasted seventy minutes, was taken by the press to mean an attempt by Martians to signal to the Earth, and as such was proclaimed all over America and Europe. The cause of the excitement, as he explained a year later to the American Philosophical Society in Philadelphia, was the reflection from a cloud on the horizon of the planet.
“Mars and its Canals” is frankly a demonstration that the planet is habitable, and that from what takes place there it must in fact be inhabited by highly intelligent beings. For that purpose the book is divided into four parts, entitled: Natural Features; Non-Natural (that is, artificial) Features; The Canals in Action; and Explanation. His general thesis, which he was to expound more fully later (and which although not essential to his argument for life on Mars he connected therewith) was that all planets go through the same process of development—varying, however, with their size which determines their power to retain the gases of their atmosphere—and that one element therein is the gradual leakage of water through cracks into its interior as the planet cools. He cites geologists to prove that the oceans formerly covered much more of the surface of the Earth than they do now; argues that the desert belts around it are of comparatively recent geologic origin, as shown by the petrified forest of Arizona; and points out thesimilarity in color, as seen from the San Francisco Peaks, of the forested hills and the painted desert there, to that of the blue-green and reddish-ochre spaces of Mars as presented by the telescope. He notes also that to get water in our deserts plants and animals have sought the higher altitudes, and are able to exist and multiply in an air less dense and a climate cooler with a shorter warm season than in their natural habitat, adjusting themselves to these conditions.
This idea of the lack of water on Mars he derives from observation of its surface and the changes thereon; for the supply of water is in great part locked up in the snow or ice of the polar caps during the Martian winters of the two hemispheres and distributed over its surface as summer comes on. Therefore he naturally begins his account of the natural features of the planet by a description of these polar snow caps, their formation and melting. In doing so he cannot resist a sarcastic reference to the endless enthusiasm, useless expenditure of money and labor, and the scientific futility of arctic exploration.
“Polar expeditions exert an extreme attraction on certain minds, perhaps because they combine the maximum of hardship with the minimum of headway. Inconclusiveness certainly enables them to be constantly renewed, without loss either of purpose or prestige. The fact that the pole has never been trod by man constitutes the lodestone to such undertakings; and that it continues to defy him only whets his endeavor the more. Except for the demonstration of the polar drift-current conceived of and then verified by Nansen, very little has been added by them to our knowledge of the globe. Nor is there specific reason to suppose that what they might add would be particularly vital. Nothing out of theway is suspected of the pole beyond the simple fact of being so positioned. Yet for their patent inconclusion they continue to be sent in sublime superiority to failure.
“Martian polar expeditions, as undertaken by the astronomers, are the antipodes of these pleasingly perilous excursions in three important regards, which if less appealing to the gallery commend themselves to the philosopher. They involve comparatively little hardship; they have accomplished what they set out to do; and the knowledge they have gleaned has proved fundamental to an understanding of the present physical condition of the planet.”
Then follows the story of the melting of the polar snows, the darkening of the blue-green areas by the growth of vegetation due to the flow of water; and a summary, at the close of [Part I] (Natural Features), of the reasons for believing that from its atmosphere, temperature, and the actual, though scanty, supply of water, Mars is capable of supporting life. In fact the presence of vegetation proves that life of that kind does exist, in spite of the fact that five-eighths of the surface is desert; and if plants can live animals might also. But, unlike vegetation, they could not be readily seen, and save in the case of intelligent operation on a large scale, their presence could not be detected. This is the significance of the canals, to which much of the observation of the last three oppositions was directed.
Close to the limit of vision, and only to be seen at moments when the atmosphere is steady, the fainter canals are very hard to observe. Percival describes the experience in this way:
“When a fairly acute eyed observer sets himself to scan the telescopic disk of the planet in steady air, he will, after notingthe dazzling contour of the white polar cap and the sharp outlines of the blue-green areas, of a sudden be made aware of a vision as of a thread stretched somewhere from the blue-green across the orange areas of the disk. Gone as quickly as it came, he will instinctively doubt his own eyesight, and credit to illusion what can so unaccountably disappear. Gaze as hard as he will, no power of his can recall it, when, with the same startling abruptness, the thing stands before his eyes again. Convinced, after three or four such showings, that the vision is real, he will still be left wondering what and where it was. For so short and sudden are its apparitions that the locating of it is dubiously hard. It is gone each time before he has got its bearings.
“By persistent watch, however, for the best instants of definition, backed by the knowledge of what he is to see, he will find its coming more frequent, more certain and more detailed. At last some particularly propitious moment will disclose its relation to well known points and its position be assured. First one such thread and then another will make its presence evident; and then he will note that each always appears in place. Repetitionin situwill convince him that these strange visitants are as real as the main markings, and are as permanent as they.”
Strangely enough fine lines, from the continuity of the impression they make upon the eye, can be recognized when of a thickness that would be invisible in the case of a mere dot. To determine how narrow a line on Mars would be perceptible, experiments were made with a wire of a certain size, noting the limit of distance at which it could be seen; and then, from the magnifying power of the telescope, it was found that a Martian canal would be visible down toabout a mile wide. From this the conclusion was drawn that the canals probably ran from two or three up to fifteen or twenty miles in width, the minimum being much less than had been thought at earlier oppositions. The distance apart of the two branches of double canals he estimated at about seventy-five to one hundred and eighty miles, save in one case where, if a true instance of doubling, it is over four hundred. Of the oases, whereof one hundred and eighty-six had been observed, much the larger part were from seventy-five to one hundred miles in diameter.
The later oppositions enabled him also to complete the topography of the planet, showing that the canals were a vast system, running from the borders of both polar caps, through the dark areas of natural vegetation where they connected, at obviously convenient points, with a still more complex network in the ochre, or desert, regions, and thus across the equator into the corresponding system in the other hemisphere. By this network the greater part of the canals could receive water alternately from the melting of the north and south polar caps, or twice yearly, the Martian year, however, being almost twice as long as our own. But to perfect his proof that this actually takes place he had to show that the canals, that is the streaks of vegetation bordering waterways, sprang into life—thereby becoming visible or darker—in succession as the water spread from the poles to the tropics; and this he did with his usual thoroughness at the opposition of 1903.
Since there was then no mechanical means of measuring the variations in visibility of the canals,—and under the atmospheric conditions at any place in the world perhapsthere never will be,—the record had to be made by the eye, that is in drawings by the observer as he saw the canals; and these, as he said, must be numerous, consecutive and extended in time. The consecutive could not be perfectly carried out because “as Mars takes about forty minutes longer to turn than the Earth, such confronting (of the observer) occurs later and later each night by about forty minutes, until finally it does not occur at all while Mars is suitably above the horizon; then the feature passes from sight to remain hidden till the difference of the rotations brings it round into view again. There are thus times when a given region is visible, times when it is not, and these succeed each other in from five to six weeks, and are called presentations. For about a fortnight at each presentation a region is centrally enough placed to be well seen; for the rest of the period either ill-placed or on the other side of the planet.” But with changes as gradual and continuous as those of the darkening of the canals this did not prove a serious drawback to the continuity of the record.
There was another element in the problem. The drawing being the estimate of the observer on the comparative darkness of the markings from time to time it was of the greatest importance to avoid any variation in personal estimates, and therefore Percival made all the drawings himself. From April 6 to May 26 he drew the planet every twenty-four hours, and although “the rest of the time did not equal this perfection, no great gap occurred, and one hundred and forty-three nights were utilized in all.... But even this does not give an idea of the mass of the data. For by the method employed about 100 drawings were used in the case of eachcanal, and as 109 canals were examined this gave 10,900 separate determinations upon which the ultimate result depended.”
For each canal he plotted the curve of its diminishing or increasing visibility as the season advanced, and this curve he called the cartouche of the canal. Now combining the cartouches of all the canals in each zone of latitude, he found that those in the several zones began to become more distinct—that is the vegetation began to come to life—in a regular and approximately uniform succession, taking from the northern arctic down to the equator and past it to the southern sub-tropic about eighty Martian days. From north latitude 72° to the equator, a distance of 2,650 miles, took fifty-two of these days, at a speed of fifty-one miles a day, or 2.1 miles an hour. Now all this is precisely the opposite of what happens on the Earth, where vegetation in the spring starts in the part of the temperate zone nearest to the equator, and as the season advances travels toward the pole; the reason for the difference being, he says, that what is needed on Earth to make the sap run is the warmth of the sun, what is needed on Mars is water that comes from the melting of the polar snows. He points out also that the water cannot flow through the canals by nature, because on the surface of a planet in equilibrium gravity would not draw it in any direction toward or away from the equator. “No natural force propels it, and the inference is forthright and inevitable that it is artificially helped to its end. There seems to be no escape from this deduction.” In short, since water certainly cannot flow by gravity both ways in the same canal, the inhabitants of Mars have not only dug the canals, but pump the water through them.
OBSERVING AND DRAWING THE CANALS OF MARS
OBSERVING AND DRAWING THE CANALS OF MARS
In recapitulating the reasons for the artificial character of the canals he shows a most natural annoyance with people who doubted the validity of his observations; and, in dealing with the evidence to be drawn from the fact that they run on great circles, that is on the shortest lines from one point to another, he writes: “For it is the geodetic precision which the lines exhibit that instantly stamps them to consciousness as artificial. The inference is so forthright as to be shared by those who have not seen them to the extent of instant denial of their objectivity. Drawings of them look too strange to be true. So scepticism imputes to the draftsman their artificial fashioning, not realizing that by so doing it bears unconscious witness to their character. For in order to disprove the deduction it is driven to deny the fact. Now the fact can look after itself and will be recognized in time.”
This last prophecy was largely verified before these three oppositions of the planet came to an end. In 1901 photography was tried without success so far as the canals were concerned. For the stars it had worked very well, for to quote again: “Far less sensitive than the retina the dry plate has one advantage over its rival,—its action is cumulative. The eye sees all it can in the twentieth of a second; after that its perception, instead of increasing, is dulled, and no amount of application will result in adding more. With the dry plate it is the reverse. Time works for, not against it. Within limits, themselves long, light affects it throughout the period it stands exposed and, roughly speaking, in direct ratio to the time elapsed. Thus the camera is able to record stars no human eye has ever caught and to register the structure of nebulae the eye tries to resolve in vain.
“Where illumination alone is concerned the camera reignssupreme; not so when it comes to a question of definition. Then by its speed and agility the eye steps into its place, for the atmosphere is not the void it could be wished, through which the light-waves shoot at will. Pulsing athwart it are air-waves of condensation and rarefaction that now obstruct, now further, the passage of the ray. By the nimbleness of its action the eye cunningly contrives to catch the good moments among the poor and carry their message to the brain. The dry plate by its slowness is impotent to follow. To register anything it must take the bad with the better to a complete confusion of detail. For the air-waves throw the image first to one place and then to another, to a blotting of both.”
There lay the difficulty which Mr. Lampland, then new to the Observatory, took up in 1903. The photographs, though better, still did not show the canals. Various adjustments were then made with the telescope; all manner of plates were tried between the rapid and the well-defining ones; and finally in 1905 upon the plates canals appeared, thirty-eight in all and one of them double.[16]On learning of the success Schiaparelli wrote in wonder to Percival, “I should never have believed it possible”; and the British Royal Photographic Society awarded its medal to Mr. Lampland.
With the observations of 1905 ended until the next opposition of the planet an exploration and a romance of which he wrote:
“To some people it may seem that the very strangeness of Martian life precludes for it an appeal to human interest. To me this is but a near-sighted view. The less the life there proves a counterpart of our earthly state of things, the moreit fires fancy and piques inquiry as to what it be. We all have felt this impulse in our childhood as our ancestors did before us, when they conjured goblins and spirits from the vasty void, and if our energy continue we never cease to feel its force through life. We but exchange, as our years increase, the romance of fiction for the more thrilling romance of fact. As we grow older we demand reality, but so this requisite be fulfilled the stranger the realization the better we are pleased. Perhaps it is the more vivid imagination of youth that enables us all then to dispense with the hall-mark of actuality upon our cherished visions; perhaps a deeper sense of our own oneness with nature as we get on makes us insist upon getting the real thing. Whatever the reason be, certain it is that with the years a narration, no matter how enthralling, takes added hold of us for being true. But though we crave this solid foothold for our conceptions, we yield on that account no jot or tittle of our interest for the unexpected.”