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 the Spree with 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 and went 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 very grave 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 the middle 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, a thing 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 interesting studies 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.