Of course traveling of this sort is attended with much peril. A man must rely wholly on himself. No wagon or saddle is available if he is injured or sick. Heavy storms may blind him and cause him to lose his way. In short, a snow-shoe trip through the Park is an undertaking which requires a vigorous physique, a determined will, and a good fund of courage. Very few, except those whose duty has required it, have ever made the attempt. But it is the unanimous verdict of those who have, that, glorious as the Park is in summer, it is even more glorious in winter. One can readily understand this to be so. Evergreen forests never appear to better advantage than when laden with snow. Ice formations always enhance the beauty of water-falls.[AX] The rolling open valleys of the Park must be doubly beautiful when robed in drifted snow. It is a pity that this silvery landscape should forever remain excluded from the general view. [AX] For picture of Grand Cañon in winter, see p. 257. CHAPTER IX. THE PARK AS A HEALTH RESORT. The climate of the Yellowstone National Park, to any one with a fair reserve of health, is of the most beneficial kind. The general public will be interested in the subject only as it relates to that season when it is possible to visit the Park. For the six months beginning with May, the average temperature will not vary much from the following figures, Fahrenheit: Maximum. Minimum. Mean. May 77° 25° 49° June 87° 30° 55° July 91° 36° 64° August 90° 36° 61° September 85° 25° 54° October 72° 18° 41° These temperatures are for Mammoth Hot Springs. For the Park Plateau they should be diminished by not less than ten degrees. No month of the year in that region passes without ice-forming frosts. It will be seen that during June, July, August, and September, the thermometer makes excursions to the neighborhood of the nineties. This, however, is only in the middle of the day, and is due to the direct intensity of the sun's rays. No such heat pervades the general atmosphere. As soon as the sun is near setting, the temperature falls rapidly. The night temperature rarely gets above 55° or 60°, and averages scarcely half as much. The Park is noted for its delightful sleep-giving qualities, which constitute no small part of its claim as a health resort.