Climbing the Pico de Orizaba

Georges Estoppey

THE Aztec name of Pico de Orizaba is “Citlaltepetl” meaning “Star Mountain.”

The Pico de Orizaba is situated between Mexico City and Vera Cruz, in Latitude 18° 59' and Longitude 97° 16'. It is the highest peak in Mexico and the third highest on the continent. It is an extinct volcano, a lone snow-capped cone the slope of which follows an approximately hyperbolic curve, and rises majestically from the tropical lowland of the Gulf of Mexico. The lips of the crater graze the sky 18,700 ft. above Vera Cruz.

James Ramsey Ullman, in his book High Conquest, says of the Pico de Orizaba: “Rising from the steaming tropical lowland near Vera Cruz, its great height and almost perfect symmetry make it one of the most beautiful mountains in the world.”

The nearest comparable peaks are Popocatepetl 17,894 ft. and Ixtaccihuatl 17,323 ft. located about 100 miles away.

The probable reason why the Aztecs called this peak “Star Mountain” is because its pinnacle is the last one to glow at sunset while the lowlands are immersed in the dim violet atmosphere of twilight, and also, the first one to shine at sunrise.

During the spring of 1941 I expressed the wish to climb Pico de Orizaba just for the sport. While studying maps and literature referring to this ascent, I was quite surprised to note the various altitudes given to Orizaba. I also read an article referring to the altitude determination of Ixtaccihuatl. In 1895, A. R. Hamilton, a member of the Alpine Club, scaled Ixtaccihuatl, Popocatepetl, and Orizaba. He described his three ascents in the Alpine Journal,1 and added a note referring to the altitude measurement of Ixtaccihuatl :

“I feel sure that the generally accepted height for this mountain is too low. In all guide-books it is put down as 16,060 ft. On the other hand, Mr. R. Whitehouse, one of the few men who have succeeded in ascending it, estimates it as ‘about 18,500 ft., or 250 ft. lower than Popocatepetl.’ Now, if Mr. Whitehouse had known the height which is now ascribed to Popocatepetl, his estimate for Ixtaccihuatl—i.e., 250 ft. lower— would make the latter 17,550 ft. This I believe to be rather too high. Judging from the vegetation, the time spent in ascending, and the combined readings of three aneroids, I am sure that the cave in which we spent the night was at any rate not less than 13,500 ft. above the level of the sea. Thence next morning we ascended over fairly steep slopes for 1½hr. before reaching the snout of the glacier, where the two aneroids we had with us gave our altitude as 15,000 ft. (I may mention in parenthesis that on my three other climbs my aneroids gave excellent results up to this height, if the guide-book altitudes for these other mountains are to be trusted.) From that point, we mounted slowly for 1½hr. more, and must have reached a height of quite 16,000 ft. before turning back. At that point we were certainly another 1000 ft. below the summit. Seen from a point on Orizaba about 1000 ft. below the top, whence the two mountains are practically equidistant, Popocatepetl appeared to overtop its neighbor by about one-third of its snowcap, say 800 ft. This would make the latter about 17,000 ft. Finally, while climbing Popocatepetl, our only glimpse of the White Lady was from a point just half an hour before we reached the lowest point of the crater, say 800 or 900 ft. below the summit. At that point we seemed about on a level with the summit of the sister mountain; we were certainly not above it. From these varied observations I feel convinced that Ixtaccihuatl is, if not 17,000 ft. high, close upon it.”

A few lines of this note are not quite clear, but let us overlook it; the problem of determining the height of a mountain by means of the barometric pressure and temperature is a more complex one than it seems to be. While reading the above note, my thoughts were carried to the Laplace fundamental barometric pressure formula. It appears that while reading their aneroids, these gentlemen have omitted the temperature, which is a very important factor in altitude determination when using the barometric pressure method.

Altitudes ascribed to the Pico de Orizaba are such as:

18,205 ft.1 given in the Alpine Journal, 1897.

18,225 ft. given by Ullman.

18,314 ft. according to measurements made by Scovell and Bunsen in 1891-92.

18,500 ft. according to some travel pamphlets of the Mexican Highway, and

18,700 ft. according to latest computation made by the National Bureau of Topography of Mexico.

Which is correct? This question led me to check the altitude while climbing Orizaba, the checking to be made by means of the method of relative barometric pressure, that is, the reading of the barometric pressure and temperature at two points at the same time. The first point is an arbitrary base the altitude of which is known and determined by the method of triangulation; the second point is the summit.

The observed data are applied to the Laplace fundamental barometric formula and the altitude is finally determined mathematically, taking into consideration the temperature and variations of gravity with respect to the latitude and altitude.

On August 21st, 1941, Mr. Guido Tanner from New York, and I, both members of the American Alpine Club, arrived in Mexico City. Being in need of barograph, altimeter, and thermometers, in company with my friends, Amador Gallardo and Guido Tanner, I went in search of those instruments. I suggested the Mexican War Department and went to the Military Aviation Field where, after formal introduction, Colonel Chagoya cordially received us. A few minutes later I had the honor to be introduced to Gen. Roberto Fierros. The reception was very courteous and our conversation, which lasted longer than I expected, was concerned chiefly with Pico de Orizaba, mountain altitude determination, formulas, and instruments. Col. Alberto H. Vieytez brought a barograph and, without formality, this instrument was loaned to me with best wishes for success. All these officers speak French and English fluently.

Through the intermediary of Amador Gallardo, the Coulier altimeter, calibrated in barometric pressure and altitude, was kindly loaned by the scientific instrument store Calpini of Mexico City. The thermometers were brought from the United States.

Since these operations were to be made at high altitude, the base being situated at 2629 m. (8625 ft.) and the summit of Orizaba 18,700 ft., the hygrometric factor was neglected, these high air strata being relatively dry.

On Sunday morning, August 24th, Guido Tanner, our guide Caldron, a medical student in Mexico City, and I, met a group of climbers at the Zocalo Plaza. They were Mr. Howard R. Coan from New York, and two of his friends, one from Philadelphia and the other from San Francisco, accompanied by their guides. They asked me if they could join our party. Without extensive formality, we all became acquainted and at 6 A.M. left Mexico City (7349 ft.) by automobile.

Some 35 miles E. of Mexico City we passed across dense and beautiful pine forest and reached Puerto del Aire, highest point on the road (10,482 ft.). The highways in Mexico are comparable to those of the Colorado National Park and are kept in very good condition, Puebla, the “Rome of Mexico” (85 miles away), city of approximately 150,000 people, was reached at 9.00 A.M. Here we stopped for a copious breakfast. We then followed the highway for approximately 35 miles up to El Seco where we made a sharp right turn leading to a country road. I first thought it was a short cut, but it proved to be the “highway” to San Andres village 14 miles away. This stretch is very picturesque, a sort of bumpy trail, cut across magnificent cornfields, mostly travelled by mules and donkeys, very dusty in dry weather and a cake of mud during rainy days. This stretch although short, required more than an hour of hard driving. What a bumpy road! We took it with a smile and did not complain against the Mexican Government, which at the present moment, at high tempo, is improving the most important necessity of the country. And so, in Mexico as in any other land, things have to be developed one after another. The only one who really did not smile was the owner of the car. While driving along this eroded trail, a terrible torture was inflicted upon the tires and springs. Nevertheless, San Andres was reached without trouble and without rain. Heavy clouds were hanging around the Pico de Orizaba.

San Andres is a picturesque small town 8625 ft. above sea level located at the base of the Citlaltepetl. This town can also be reached by the Mexico-Vera Cruz Railway in approximately six hours from Mexico City. The Aztec name for San Andres is “Chalchicomula” meaning “Spot of Precious Stones.” We were cordially received by Mr. and Mrs. Valdermana, owner of the Fausto Hotel where a good lunch was served.

While the horses, mules and donkeys were saddled and packed, I took care of the instruments which were set and observed as follows:

At time “T” of departure from San Andres, the barometric pressure on the Coulier instrument having a fixed pressure scale calibrated according to standard atmosphere was observed. The figure 2629 m. (altitude of San Andres Plaza) of the movable altitude scale inserted in the Coulier instrument which had to be carried to the summit of Orizaba was set to coincide with the pressure needle. This altitude scale was merely used to observe approximate altitude while climbing and has no connection at all with the pressure data used in our altitude computation. This Coulier instrument of the latest type is four and three-quarter inches in diameter and the metallic parts are compensated for variation of temperature. The barograph was set in motion according to local time “T” and was deposited at the Pasteur Pharmacy located on the main plaza of the town (2629 m.). Next day, temperature had to be recorded every hour by the pharmacist. The barograph was used only to automatically record the variation of barometric pressure between time “T” of departure from San Andres and time “Ta” of arrival at the summit. No attempt was made to set and synchronize the two instruments at the same barometric pressure. Only the variation of pressure indicated by the barograph between time “T” and time “Ta” was to be added or subtracted from the pressure observed on the Coulier instrument at time “T.” To increase the accuracy of scale reading, magnifying glasses had to be used. The horizontal distance between San Andres and the summit of Orizaba is 10.3 miles. All these observations and operations being completed at 2.00 P.M., we left town by auto, and half an hour later, Capilla, located about 9500 ft. above sea level, was attained. Here we met our horses and mules which had to carry us to the Cueva del Muerto, situated at timberline about 14,000 ft. above sea level. The caravan was composed of nine climbers and three extra men who attended to the horses and the mules.

At Capilla, the start was detrimental to me for I met with an accident. At the most unexpected moment, I was kicked by a mule. My left hip was slightly bruised and stained with a large splash of colors varying from red to black. The pain was so acute I thought the expedition to Orizaba had ended for me. A few minutes later, however, the discomfort decreased to such an extent that I decided to go on, and so went astride my horse. At 3.00 P.M. the whole caravan started to move upward, first across cornfields, then along gentle slopes and dense vegetation. Further up, another incident occurred; the mule which had bumped me off played another trick, but to his master this time. The mule was heavily loaded and was followed by his master who intermittently was hissing “Obida, obida,” meaning “Move on.” I imagine this monotonous and continuous utterance grated on our mule’s nerves for, without warning, she kicked and sent her master into the ditch. As no harm was done, everybody, including myself, had a good laugh at this comedy, but I began to wonder how many times our dear mule would display such a charming temper.

The caravan moved upward among magnificent pine trees. The trail, or more precisely, a simulated trail, covered with heavy grass became very steep, difficult for the horses and mules to walk on. We then followed the bottom of a narrow canyon which gave access to a high plateau scattered with cinders and small rocks. A short distance from the cross located at the saddle we had the first view of the majestic snowy peak. It was 7.00 P.M. when the Cueva del Muerto was attained. We are at the timber- line, approximately 14,000 ft. above the sea. Bushes and stunted trees as we find at the timberline of the Rockies and the Alps are rare. The vegetation ends abruptly with superb pine trees rising 40 to 60 ft. above the ground. A great variety of flowers of vivid colors soften the wilderness of this high region. Some species are so luxuriant that their stems reach two to three feet in height. The Cueva is a grotto five to six feet high, ten feet deep and approximately twelve feet long. The air was dry and cold. A fire was built and the bivouac started immediately. This four- hour trip on horseback did not aggravate my hip and while falling asleep, I hoped that by next morning the pain would have completely vanished.

We arose at 2.30 A.M., took a frugal breakfast and at 3.00 A.M. set out for the ascent. The first hour was made on horseback up to Puerto de los Azufreros, a few hundred feet higher. The horses then were sent back to the bivouac and we started to climb the cone the slope of which follows closely a hyperbolic curve; in other words, the gradient increases as altitude is gained. The first part of the ascent was made in cinders, mixed with small rocks covered with a coating of two inches of fresh snow which had fallen during the night. The first patch of what might be called “eternal snow” was met at approximately 15,000 ft. We took to the left and climbed the rocky ridge, a sort of stairway each step of which measured one-half to two feet in height. Reaching 15,500 ft., Guido Tanner and his companion gave up and returned to the Cueva. I kept climbing, and considering the altitude, my heart and lungs were functioning normally; that is, the heart was beating a little faster and breathing was a little slower, conditions which are normal to any climber toiling at high altitude. But— there is a but—the continuous lifting and twisting of the body while climbing this long stairway reacted against my damaged hip and caused painful discomfort. At 8.00 a.m. we reached 16,600 ft., where motion pictures were taken. The pain was so acute that I decided to desist, a decision which to a mountaineer is mentally more painful than the physical pain I was enduring. The weather was fine, the temperature relatively high and the sky slightly cloudy.

I gave my Coulier instrument, thermometer, and all necessary instructions to Mr. Coan, a professor of languages in Brooklyn, N. Y., F. Richard, student in Philadelphia, and S. Fish, student in Oakland, Calif. A last look toward the summit and then it was Adios Citlaltepetl. The remaining five, comprising the three above mentioned gentlemen and their two guides, continued their climb while I and my guide returned to the Cueva. Climbing down was relatively slow but not as troublesome as I expected. The ice-axe was used as a cane or crutch which considerably relieved the pain, so the Cueva was reached without too much discomfort. We ate, rested, and waited for the other group who returned quite late, being caught in a snowstorm while climbing down and temporarily losing their way. I came down astride my horse and at 10.00 P.M. everybody was back at San Andres.

The five climbers had reached the Cruz de Hierro (the Iron Cross) at which point, barometric pressure and temperature had been recorded. The true summit, which is approximately 100 ft. above the Iron Cross, was not reached by these gentlemen.

At 11.00 p.m. we departed from San Andres arriving at 1.00 A.M. in Puebla where the night was spent. The next morning we visited this interesting city, and Mexico City was reached the same evening. It was a success for Mr. Coan and his companions and a miss for me, but I was not considering myself beaten. Citlaltepetl was like an irresistible magnet. I wanted to try it again, for the true summit of the Orizaba had not been reached by our companions; therefore the altitude checking job was not completed and I wished to finish it.

During the following days my hip was treated and then I decided to try it on the Tzinantecatl (crater of Toluca) 15,036 ft., which is higher than any mountain in the United States. So, on September 5th Tanner and I went to visit this twin crater at the bottom of which are two lakes 13,621 ft. above sea level. This magnificent spot is easily reached by automobile in one and a half hours from the town of Toluca or approximately three hours from Mexico City. Arriving at the lake (in city clothes) I said to Tanner: “Just wait for ten minutes, I am going to try my hip on these steep rocky slopes leading to Bell Tower.” But the tower being more attractive than the car, I climbed and reached the saddle, more than 1200 ft. above the level of the lake. I took some moving pictures of the surrounding scenery and returned not in ten minutes, but an hour and three-quarters later, Tanner greeting me with a sour smile and a shower of remarks. Indeed, it was late and cold. “Well, well,” said he, “your hip does not seem to hurt you any more; why don’t you try Orizaba again?” In a compassionate tone I replied: “Fine! That is precisely what I have in mind.” All arguments ended with enigmatic expressions. Silently I swallowed the shower and forgave him, for he and the chauffeur were shivering and their discomfort was intensified by the effect of altitude.

We drove back toward the valley and so, as the altitude decreased, the temperature increased and simultaneously the good humor of Tanner returned to normalcy. At 12,000 ft. we arrived at a small ranch. All of us were hungry and purchased some delicious tea cakes. They were so tasty that more than a dozen passed the palate before we continued our trip toward Mexico which was reached in the evening.

Next day we visited Mr. Otis McAllister, founder and president of the Club de Exploraciones de Mexico who courteously loaned me a pair of crampons which were to be used for the climb of Orizaba.

On September 11th, Tanner and I left Mexico City by train for San Andres station from where a rustic tramway carried us to San Andres village, five miles away. We again found ourselves at the Hotel Fausto. With the exception of myself everybody was speaking Spanish, and Tanner, who speaks the language fluently, was a great help in translating exactly what I wanted; that is, how I wanted things to be done in order to obtain maximum results. This time the caravan was composed of myself, a 25-year-old Mexican guide, a porter to carry food, instruments and photographic apparatus, and also two men to attend the horses. A 19-year-old husky fellow, the guide’s brother, desired to accompany us and asked me if I would let him do so. He stated that he wanted to get acquainted with rarefied air, and wished to become a guide later on. As he was a healthy fellow, I acceded to his desires and everybody was happy. The caravan was composed of six men plus horses, mules and two extra packing mules.

Barometric observations made, at 11.00 a.m., astride my horse I said good-bye to Tanner who went north toward Mexico City while I went south toward the Pico de Orizaba. The weather was fine. An hour later we arrived at Capilla, the spot where I had been kicked by the mule, which, by the way, was again a member of the caravan. She was carrying a heavy load. As all was well, what was the use of worrying about the past incident? A mule is a mule and there is 110 use to argue. Briefly, the Cueva del Muerto was reached at 4.00 p.m. without mishaps. The bivouac was set as before and at 2.00 a.m., September 13th, we started the ascent of Orizaba. The moon was playing hide and seek with the clouds, which themselves were gamboling along the slopes of the big snowy cone. At 15,550 ft. (4.30 a.m.) we were swept by a terrific wind and at 16,000 ft. (5.30 a.m.) a heavy snowstorm was slapping our faces. Within a few minutes our clothes were nothing but a hard sheet of ice. Decidedly, the Citlaltepetl, the Star Mountain, was displaying an unexpected temper. Her rage was so bitter that we decided to take refuge behind a huge rock. We were protected from the biting wind and snow, but the ambient temperature was not such that we could remain inactive in our icy garb. Was this haughty Star Mountain trying our physical endurance and nerves? Were we passing the acid test before receiving a deserved reward? Such is the mountain! Figuratively speaking, this peak is highly temperamental, she is apt to change her mood at any time. She shows herself as she really is and measures men at their true value, in character, will power, patience, prudence, and endurance.

My companions sat on frigid rock. I remained standing. Their faces were displaying expressions of discomfort and disgust; their eyes were turned downward in the direction of the Cueva, hidden by a white and opaque screen of falling snow. The wind in fury whistling at high pitch sounded like a mystical, cynical and satirical symphony. It was impressive. It was a composition suddenly created and played by the mountain itself. The decors of this vast music-hall was whirling snow; the musicians were the invisible wind and the lodge coated with ice. What a comfort! It was depressing—no one spoke but things were felt. The face of my guide turned toward mine. His eye had an anxious and inquisitive expression seeming to ask, “What is next?” Having some knowledge about weather conditions in high mountains, I had a feeling that this inferno could not last longer than an hour or so, and so, smiling and hoping for the best, I lifted my head toward the invisible summit and turned thumb upward. Trusting each other, impeded by our frigid armor, we threw ourselves into the midst of the raging tempest. Fighting against the elements, slowly, very slowly, upward we went. This lasted for more than four hours, then it abated, and suddenly as if by magic, we emerged from the clouds. The sky was clear, a sky of intense dark blue. What a contrast! Here we received our reward. What a panorama! What a stage! What grand simplicity. The views were few but immense, fantastic and austere, and so magnificent that I had the impression of emerging from a nightmare to pass the gates of an unbelievable fairyland. The snow cone of the Star Mountain like an immense blue white diamond cut in myriad facets was glistening under the ultraviolet rays of a gleaming sun. Below, a vast ocean of clouds rolling silently in fantastic waves was extending to the horizon, where Popo was flirting with his siren Ixta. Everything below 17,000 ft. was immersed in grey mist.

Popocatepetl means “Smoking Mountain” and Ixtaccihuatl means “White Lady” or “Sleeping Beauty,” this on account of the snowy profile of the mountain which closely resembles a sleeping woman.

Seventeen thousand three hundred feet (9.30 a.m.) and all is well. Upward we go. The slope becomes steeper and steps are to be cut in the frozen snow. The climb proceeds slowly but surely. We passed to the left of a rock reef, the rim of the crater, and at 12.45 the Cruz de Hierro (Iron Cross) was reached. The cross is situated in a crag filled with snow at the foot of the above mentioned reef and slightly inside the crater. The cross is ingenuously built of gas pipe approximately one inch in diameter and of sectional structural beam approximately 12 x 12 inches. Judging the length of the upper part which protrudes from the snow, the total height of the cross may be estimated at ten feet. Still and moving pictures were taken, observation of barometric pressure and temperature were made, and we started for the true summit which is a twenty-minute climb from the cross. The top was attained at 1.30 p.m.. All was well. Everybody was happy. My guide was so enthusiastic on account of our success that he kissed me by surprise, a Mexican custom. Again, barometric pressure and temperature were observed. The summit, which was then bare of snow, is formed by small black and yellow stones and is located at the left of the cross and above it. While facing toward the crater, one can smell slight traces of sulphur. The diameter of the rim is relatively small, the inside wall very steep and deep. Its rugged rim is formed by huge crags and sharp rocky turrets rising like flames. Small masses of clouds were whirling into the cone. The general aspect of this crater is fierce and gives an idea of how terrific an inferno it must have been when in activity.

Clouds start to swarm above our heads and below our pinnacle. We celebrate with a banquet composed of oranges, chocolate, dried prunes, and with tea we drink a toast to the Citlaltepetl and then “good-bye, Star Mountain.” The descent was made quite rapidly. While we were losing altitude, as if by magic, the clouds burst away so as to give us free view and free passage. The Cueva was visible and the towns as Esperanza, Orizaba, and Fortin de las Flores, appearing like nests on the lowlands, were sighted through the scattered floating clouds.

We arrived at the bivouac at 4.00 p.m. There we were greeted by a group of young climbers who intended to ascend the Torresillas, little towers situated at the foot of the Citlaltepetl. Tea was boiling and a picnic was welcomed. At 5.45 p.m. horses and mules were saddled and packed and we proceeded downward to San Andres. The big cone was wearing a coat of clouds again and the weather was menacing. It was dark as ink when we reached the dense forest; lightning was illuminating our way, the thunder was clamoring Wagnerian music and a tropical rain drenched our bodies as if we were receiving the baptism of the Great Mountain. Such was the grand finale!

During the whole trip our temperamental mule comported herself correctly. At 9.30 p.m. we were back at the Fausto Hotel, where a shower, warm meal and a clean bed were most welcome. My face was branded with the seal of Citlaltepetl. Having worn goggles, the exposed part of the face was sunburned, so burned by the intensive ultraviolet rays that I gave the impression of wearing a brown-black mask.

Next day noon, I left for Fortin de las Flores (3303 ft.) some 55 miles E. of San Andres or 72 miles W. of Vera Cruz.

Fortin de las Flores is a delightful tropical town, a paradise set on the slope of the high mountain where ideal climate combines with luxurious trees, plants and flowers. The modern Ruiz Galindo Hotel built in typical Mexican style with its large swimming pool is as comfortable as it is charming to look at. During the evening, pleasant music filled the aromatic air. What a relaxation! What a delightful and indefinable feeling I was experiencing while recalling the intense moments spent on the big mountain.

Next morning at six, as if I had been called, I suddenly awakened and opened the shade of my window. What a surprise! Citlaltepetl in all her glory, pink hued by the rising sun! What an imposing jewel! I took a few moving pictures, but before 8.00 a.m. had struck, the show was over and again she hid herself behind a screen of grey clouds. The same day I arrived in Vera Cruz, 18,700 ft. below Citlaltepetl’s summit, greeted by more than 100° Fahrenheit and a steaming tropical humidity. What a contrast in altitude, air density, temperature and moisture within 48 hours!

On my way to the airport, I went to Macomba, a magnificent hotel, Spanish style, built on a cliff along the shore of the Gulf of Mexico some three to four miles S. of Vera Cruz. From there I reached Mexico City by aeroplane.

Note

The Pico de Orizaba can easily be scaled in clear weather by any well- trained mountaineer accustomed to high altitude. It must be borne in mind that climbing at 18,000 ft. or more is a different story from climbing hills 6000-12,000 ft. above sea level.

Rarefied air such as breathed on high mountains may surprise anyone not accustomed to it, no matter how good a physical condition one may enjoy and display at low level. High altitude has the tendency to decrease physical energy, as in the “mountain sickness” so many times observed and felt by aeroplane passengers. The comfortably seated air traveller without necessity of stretching his imagination can easily conceive the amount of human energy which is required in climbing high mountains.

Referring to weather conditions, it is said that the most favorable period to climb Orizaba is November, December, January, and after February. March and April are relatively propitious. During May, too much loose snow is encountered. June and July are rainy months. August and September form the worst period. Wind and snowstorms at high level and tropical rain in the valley occur almost every day. During these four months, especially September, one may meet with heavy snowstorms while climbing and return with relatively fair weather and vice versa. Conditions in October are good.

From the experience I had with my native Mexican guides and their helpers, it can be said that they are honest, dependable and conscientious.

From observations made August 25th at the Iron Cross and at San Andres and on September 13th, 1941, at the Iron Cross and true summit, and mathematical computations, it has been found that the difference in height between the base of San Andres and the true summit (not the Iron Cross) is 3067 m. (10,063 ft.). The altitude of the base of San Andres is 2629 m. (8625 ft.), a height determined by triangulation. So the altitude of the true summit of the Orizaba is 5696 m. or 18,688 ft.

During my visit to the National Bureau of Topography of Mexico I had the honor to be received by Ing. A.M. de la Llave, Director of the Bureau, who courteously displayed the latest National Map on which the Pico de Orizaba bears the altitude of 5700 m. and 2629 m. for San Andres. The method used by the Mexican Government in determining the altitude of Orizaba is the barometric pressure and temperature observation and mathematical computation made according to the Laplace fundamental formula.

So, the altitude of 5700 m. (18,700 ft.) is officially recognized by the National Bureau of Topography of Mexico. The slight difference between the above value, 5700 m., and my figures may be due to the fact that the summit was bare of snow when barometric observation was made, or to slight difference in coefficients used in this formula, or to slight scale-reading errors.

In Washington, D. C., I had the honor of meeting Dr. W. G. Brombacher, of the Bureau of Standards, with whom I had a long and interesting discussion pertaining to my work. Dr. Brombacher had done considerable and very interesting work referring to the determination of the altitude of aircraft, and undertook the delicate task of checking the altitude of the famous stratosphere flight (Rapid City, S. D.) made by Capt. Stevens. Dr. Brombacher carefully examined the method I used, which was found to be correct. So, the altitude of Orizaba is 5696 m. (18,688 ft.) or 5700 m. (18,700 ft.). The official figure, 5700 m. (18,700 ft.), given by the National Bureau of Topography of Mexico can be accepted.

1“Ascents in Mexico,” A.J. 18 (1897), 456.

1This figure was determined by Prof. Angelo Heilprin of the Philadelphia Scientific Commission in 1890 and is reported in the Proceedings of the Academy of Natural Sciences of Philadelphia (1890). Heilprin was an original member of the American Alpine Club and its first vice-presi- dent. [ED.]