"As the sun rises from day to day, week after week, and month after month, in unclouded brightness during the dry season, and pours down his unbroken rays on the dry, unprotected surface of the country, the heat becomes so much greater inland than it is on the ocean, that an under-current of cold air, bringing the fog with it, rushes over the coast-range of hills, and through their numerous passes, towards the interior.
"Every day as the heat, inland, attains a sufficient temperature, the cold, dry wind from the ocean commences to blow. This is usually from eleven to one o'clock; and as the day advances the wind increases and continues to blow till late at night. When the vacuum is filled, or the equilibrium of the atmosphere restored, the wind ceases: a perfect calm prevails until about the same hour the following day, when the process re-commences and progresses as before, and these phenomena are of daily occurrence, with few exceptions, throughout the dry season.
"The cold winds and fogs render the climate at San Francisco, and all along the coast of California, except the extreme southern portion of it, probably more uncomfortable, to those not accustomed to it, in summer than in winter.
"A few miles inland, where the heat of the sun modifies and softens the wind from the ocean, the climate is moderate and delightful. The heat in the middle of the day is not so great as to retard labor, or to render exercise in the open air uncomfortable. The nights are cool and pleasant. This description of climate prevails in all the valleys along the coast-range, and extends throughout the country, north and south, as far eastward as the valley of the Sacramento and San Joaquin. In this vast plain the sea breeze loses its influence, and the degree of heat in the middle of the day, during the summer months, is much greater than is known on the Atlantic coast in the same latitudes. It is dry, however, and probably not more oppressive. On the foot-hills of the Sierra Nevada, and especially in the deep ravines of the streams, the thermometer