Popular Science Monthly/Volume 27/July 1885/A Great Winter Sanitarium for the American Continent

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JULY, 1885.


By Professor EDWARD FRANKLAND, M. D., F. R. S.,


THE great importance of a winter sanitarium for patients suffering from or threatened with consumption and other allied diseases has long been recognized and acted upon in Europe. The favorite resort of this description is the valley of Davos, in the Engadine, in Switzerland, where, at an elevation of five thousand four hundred feet above sea-level, the patients enjoy, during the winter months, in a sheltered position, brilliant sunshine, and an early equable sun temperature from sunrise to sunset.

Dr. Hermann Weber, one of the highest authorities in Europe on chest-diseases, thus summarizes the physiological effects of the climate of Davos:

1. Increased activity of the skin, better nutrition, and invigoration of the skin.

2. Strengthening of the heart and the contractile fibers of the vascular system, with augmented frequency of the heart's contractions at first, but reversion to the normal state after a longer sojourn, together with greater force of each contraction, and thereby increased suction-power.

3. More rapid respiration at first, but return to the normal rate after a few days. Probable increase of depth of inspirations. Strengthening of the respiratory muscles, and probably also of the elastic fibers of the finest bronchial branches. Increased flow of blood through the lungs.

4. Generally a marked increase in the excretion of water through the lungs, and increased and facilitated excretion of carbonic acid.

5. In most cases, transient or continued increase of appetite, ingestion of food, digestion and assimilation.

6. Thereby improved production of blood and nutrition of the organs.

7. Greater energy of nervous and muscular action.

8. In most cases, improvement of sleep.

9. Probable augmentation of tissue-change.

During last fall I became acquainted with an elevated plateau in the United States which rivals if it does not even surpass Davos in the excellence of its winter climatic conditions. I allude to that most interesting tract of territory—the Yellowstone National Park.

The beneficial effects of a winter climate like that of Davos depend upon the concurrence of several conditions which are difficult to secure at a lower elevation than that just indicated. In the first place, the sun's rays are far more powerful at great than at low elevations, and their intensity is much more equable throughout the day; thus the temperature in sunshine observed by me at Davos on the 26th of December was 89·2° Fahr. twenty-five minutes after sunrise, 108·5° Fahr. at noon, and 91·6° Fahr. at thirty-five minutes before sunset. And the intensity of solar radiation at Davos is such that, on the 22d of December, I obtained, in a box lined with padded black cloth and covered with plate-glass, a temperature of 221° Fahr., or 21° above the boiling-point of water at Davos (200° Fahr.).

Besides the intensity of solar radiation and its comparative uniformity during the day, the rarity and calmness of the air are important factors among the causes of the peculiar climate of Davos. With the barometer standing at 615 millimetres, the weight of air in contact with a given surface of the skin is about one fifth less than it is at the sea-level. The excessive dryness of the air at Davos has probably but little special influence upon the sensation of heat and cold, because the maximum proportion of aqueous vapor present in air near the freezing-point is everywhere small, and the specific heats of equal volumes of air and aqueous vapor are not widely different. On the other hand, the absence of suspended watery particles in the air has, no doubt, very considerable influence in preventing the chilling of the skin. Not only are such liquid particles present when there is visible fog, but they often exist in great numbers when the air presents a perfectly transparent appearance. The most important influence upon the sun-temperature, however, is the reflection of solar rays from the snow. The valley of Davos has precipitous sides and a flat sole, and the hotels are situated on the northwest slope of the valley; consequently they receive, in winter, the scattered solar rays reflected from a large area of snow. A considerable proportion of the thermal rays of the sun falling at an acute angle upon a surface of snow is known to be reflected.

It is obvious that this action of extensive reflecting surfaces of snow must exert a powerful influence upon the maximum temperature of places favorably situated for receiving the reflected rays; and, moreover, where the proportion of heat reflected varies (as it has been proved to do in the case of water, and as it doubtless also does in the case of snow) inversely as the angle formed by the incident rays and the reflecting surface, this action must materially contribute, especially in winter, to the maintenance of an approximately uniform sun-temperature throughout the day. At Davos, and similar elevated stations, however, the comparative freedom of the air from suspended particles must, to a great extent, contribute to such a result; for, as pure and dry air is transcalent and reflects heat but very slightly, the horizontal sunbeams, passing through such air, would be nearly as powerful as vertical rays.

The peculiar winter climate of Davos depends, therefore, upon the following: conditions:

1. Elevation above the Sea.—This single condition favors a genial and wholesome winter climate in several ways. In the first place, by reducing the weight of cold air in contact with the body, whereby, even with a much lower thermometer, the air, if still, feels warmer at an elevated station than in the lower and denser regions of the atmosphere, in consequence of the slower abstraction of heat from the body. In the second place, the air at great altitudes is more permeable to the heating rays of the sun, owing both to its dryness and to its freedom from dust and suspended particles generally. In illustration of this I have made many experiments, chiefly in England and Switzerland, and an abstract of the results obtained is given in the following table:

above sea-
Feet Degrees. Degs. Fahr. Degs. Fahr.
Oatlands Park, Surrey 150 60 74·7 86·0
Riffelberg, Zermatt 8,428 60 81·9 76·1
Hörnli, Zermatt 9,491 61 86·6 68·2
Gornergrat, Zermatt 10,289 61 84·6 57·6

Whitby, Yorkshire 60 50 68·0 90·0
Pontresina, Engadine 5,915 49 79·2 79·7
Bernina Hospitz, Engadine 7,644 51 83·5 66·4
Diavolezza, Engadine 9,767 50 107·1 42·8

It is thus evident that, although the air-temperature continually decreases as we ascend, the sun-temperature as regularly augments. The horizontal line in the table divides the observations into two groups, in each of which the sun's altitude was approximately the same. In these, and similar observations described further on, the air-temperature was found by placing an ordinary mercurial thermometer upon a sheet of white paper and shading its bulb with a small arch of similar paper doubled, the sun-thermometer (blackened bulb in vacuo) was also placed either upon white paper or upon snow, and the numbers in the column headed "sun-temperature" were obtained by deducting the readings of the air or shade thermometer from those of the sun thermometer. Thus, on the Diavolezza, the reading of the air-thermometer (42·8°), being subtracted from the reading of the sun-thermometer (149·9°), left the number 107·1° as the sun-warmth, or the temperature, above that of the surrounding air, to which the sun's rays raised the blackened bulb in vacuo.

The very high sun-temperature observed on the Diavolezza was recorded at a station surrounded by snow-fields in brilliant sunshine, and the thermometer was placed upon snow.

Not only is solar radiation much more intense at great altitudes, but it is also more equable during the whole day, inasmuch as the comparative absence of suspended matters in the air renders the thermal power of the rising and setting sun more nearly equal to that of the meridional sun. Thus it has been observed that, at or near the sea-level, the sun-temperature increases about 15° Fahr. between 8.30 a. m. and noon, and decreases to the same extent between noon and 3.30 p. m.; whereas on the Riffelberg, 8,428 feet above the sea, the increase and decrease between the same hours are only 9° Fahr. These observations were, however, made in summer; in winter, the difference between the two stations would doubtless be still greater. Moreover, an elevation of 5,000 or 6,000 feet places us, especially in winter, to a great extent above the region of cloud, and thus enables us to enjoy a bright sun at time when clouds effectually cut off his rays from lower altitudes.

Lastly, and this is of the highest importance to invalids, the air at great elevations is characterized by comparatively great freedom from zymotic matters. By numerous and ingenious experiments Pasteur found this to be the case at a height of 6,300 feet, on the slope of Mont Blanc, and Tyndall at an elevation of 6,730 feet, on the Bel Alp, in Switzerland.

2. Reflection from Snow.—Although the air-temperature in midwinter, at elevations of from 5,000 to 10,000 feet, differs but little from that of much lower levels in the same localities, the low temperature prevails for a longer time. Thus the valley of Davos and the surrounding mountains are usually thickly covered with snow from November to the beginning of March, and the solar heat reflected from this snow is an important factor in the production of the genial winter climate of Davos. By laying a sun-thermometer on surfaces of different materials, I have demonstrated the high reflective power of snow. The following summary of the results of these experiments shows the degrees to which the blackened bulb in vacuo was raised when laid in the sunshine upon each of the materials experimented with:

White paper 116·6° Fahr.
White linen 116·1 "
Snow 111·0 "
Metallic minor 97·5 "
Common mirror 97·5 "
Light-colored soil 96·3 "
Parched grass 95·3 "
Gray rock 88·4 "
Green grass 88·2 "
Black silk 84·0 "
Black caoutchouc 82·2 "
Black merino 80·4 "

White paper and white linen were therefore the most perfect reflectors of solar heat; but the efficiency of snow was but slightly inferior, while it greatly surpassed that of even polished metal.

The relative proportions of direct and reflected solar heat, falling upon a body in sunshine surrounded with snow, has not been determined, although it has been ascertained where water is the reflecting surface. Thus, M. Dufour has measured the proportions of direct and reflected solar heat incident at five different stations on the northern shore of the Lake of Geneva. He found that the proportion of reflected heat was as much as sixty-eight per cent of the heat directly incident from the sun, when the sun's altitude was between 4° 38" and 3° 34". At about 70° altitude, the proportion was between 40 and 50 of reflected to 100 of direct heat; and, even at an altitude of 16°, the proportion was between 20 and 30 of reflected to 100 of direct heat; but when the sun was higher than 30° the reflected heat was hardly appreciable. My own observations confirm these results, for I found at Alum Bay, Isle of Wight, that the reflection from a ruffled sea, at 6.45 p. m., in May, added no less than forty-four per cent to the direct solar heat.

It is obvious, therefore, that the Davos sanitarium is much indebted to its snow-covered valley for a winter day-climate which is so genial as to allow the patients to spend nearly the whole of every sunny day in the open air, although the temperature of the air may be 15° or 20° below the freezing-point. Five minutes after sunrise, many of the patients walk in the open air without any special wraps, and some of them even without overcoats. In the brilliant sunshine, one feels comfortably warm sitting in front of the hotel in a light morning coat.

3. Freedom from Air-Currents.—Davos is well sheltered from general atmospheric movements, and, as the surrounding snow can not be warmed above the freezing-point, no local currents or valley-winds can be set up. An almost uniform calm, therefore, prevails during the continuance of snow. This immunity from air-currents is of the highest importance to the patients, for, without it, they would not be able to sit out-of-doors and enjoy the free and comparatively germless air as already described. In still though cold air the skin is less chilled than in much less cold air which impinges with considerable velocity upon the surface of the body. The effect of motion through the air upon the sensation of warmth and cold at Davos is very striking. Sitting perfectly still in the sunshine, the heat in midwinter is sometimes almost unbearable; on rising and walking about briskly, a delicious feeling of coolness is experienced; but, on driving in a sledge, the cold soon becomes painful to the unprotected face and hands.

Such are the conditions prevailing at Davos, and producing the delightful climate of this winter resort. They may be thus briefly summarized: 1. Great elevation above sea-level; 2. A continuous, and, during winter, permanent covering of snow; 3. A minimum of watery vapor in the air; 4. A clear sun; 5. A clean atmosphere, free from zymotic germs, dust, and fog; 6. A sheltered position, favorable for receiving both the direct and reflected solar rays.

I have been thus particular in describing these conditions in order to make clear the capability of the Yellowstone plateau to provide a similar beneficent winter climate for invalids.

From my own observations, and from inquiries made on the spot, I am of opinion that the Yellowstone National Park possesses, in a high degree, all these essential conditions. In elevation above the sea it surpasses Davos; the great plateau of the park is between 7,000 and 8,000 feet above sea-level, while it is stated that not one of the narrow valleys dips below 6,000 feet. The mountain-ranges, partly surrounding and partly within the park, rise to heights of from 10,000 to 12,000 feet. I should anticipate, therefore, that all the advantages which, as a winter resort for invalids, Davos possesses from its elevated position, would be enjoyed even in a greater degree in the Yellowstone Park. The period of permanent snow is longer, so that invalids could remain there probably until the end of April, whereas the melting of the snow generally compels them to leave Davos early in March, when the climate of the valleys is peculiarly unfavorable for chest-complaints. It is to be expected, from its greater elevation, that a still clearer sky and a larger proportion of sunny days would be experienced in the Yellowstone Park, while the wholesomeness of the air would be still more marked, owing to its comparatively greater freedom from zymotic matter.

The latitude of Davos is 47°, and the Yellowstone Park lies almost entirely between the forty-fourth and forty-fifth parallels. The winter temperature at Davos varies from 32° Fahr. down to 22° Fahr., and that of the park would probably observe nearly the same extremes. The selection of suitable sites for hotels and sanitary dwellings is, of course, of the highest importance. The only hotel at present existing the Mammoth Hot Springs Hotel is not favorably situated, but, even in my comparatively limited excursions in the park, I saw numerous most eligible sites for such establishments sites sheltered from northerly winds, either by abruptly elevated ground or pine-forest, with a wide expanse of prairie to the south. A free horizon southward is of great advantage to a winter climate, not only because the practically unlimited surface of snow secures the most perfect reflection of solar warmth, but also because there is no obstruction to the rays of the rising and setting sun. I consider the want of a free southern horizon to be an important defect in the situation of Davos, for it reduces in winter the daily period of sunshine by more than two hours, or, in other words, it diminishes the length of day available for patients in midwinter by more than one fourth. In respect of daily duration of sunshine, therefore, the advantage of the park over Davos would be considerable.

In order, however, that it may be fitted for the reception of invalids, much will have to be done besides the building of hotels. The lawlessness and extortion which at present prevail throughout the Yellowstone National Park must be made to cease, wholesome food must be substituted for the indigestible material which now does duty for beef and mutton, and the almost impassable roads must be seriously taken in hand.

The one drawback to the park is its great distance from the masses of the American population; but, in the first place, distances which are almost prohibitive to travelers in Europe are thought little of in America; and, secondly, the comfortable, not to say luxurious, traveling: on American lines would render the transit from the Eastern cities of the United States scarcely more formidable than that from London to Davos, the driving portion of the journey being, in fact, much shorter in the American route.

We are as yet too little acquainted with the chemical composition of the hot springs, geysers, and mineral waters so profusely distributed throughout the park, to form any trustworthy opinion of their medicinal virtues, but the physical properties of water are much the same everywhere, and, by a judicious selection of sites, the enormous advantages of an unlimited supply of natural hot water and steam for baths and heating purposes could easily be secured, and this without interfering with the wonders and aesthetic beauties of this most extraordinary and interesting region.

At present, the park, so generously set apart by Congress for the enjoyment of the American people, is utilized only by a very limited number of tourists, in the few months of a very short summer, and it seems a pity that such a magnificent possession should not be much more extensively used. Dedicated during the winter months to the purposes I have here advocated, it would constitute a winter sanitarium unequaled in the world, restoring to health and vigor not only thousands of persons suffering from incipient chest-diseases, but also still greater numbers of the overworked populations of the States and Canada.