86 THE CLIMATE. 



close. Lilacs, fleurs de lis, gladiolus, (byzantinus,') pinks, and a host of other garden flowers, 

 unfold their wondrous petals; and from the plants that bloomed in early September, ripe 

 strawberries may be gathered before the middle of November. In this last month the olive- 

 trees flower, and maize is in tassel ; and towards its close not only are the grain-fields golden- 

 hued in the sunlight, but natural pasturage and herbs on the hill-sides, no longer receiving 

 supplies of moisture, have been scorched under the same powerful influence. After this, ver- 

 dure remains only in the deeply shaded ravines, in the vicinity of streams, or where the soil 

 is artificially irrigated ; and all the surrounding hills look dark and denuded, the giant Quisco, 

 (Cereus Q.), with its black, branching arms, as projected against the sky, corroborating the 

 impression that no vegetation has withstood such heat and drought. 



From an examination of hourly observations, made on the 21st day of each month, it appears 

 that the barometer not only stands about 0.08 inch lower in summer than in winter, but also 

 its oscillations are more uniform, and the hours of maxima and minima fall later in the day. 

 Like facts are shown in the means of the tri-hourly observations ; and we find that the greater 

 maximum takes place nearer to 10 than to 9 o'clock ; the afternoon minimum invariably after 

 4 o'clock. In this season the average pressure is 28.042 inches, and its mean daily range 0.040 

 of an inch. These are the months when the aqueous atmosphere is most disturbed ; when the 

 temperature of evaporation, which, at an hour or two after sunrise, may be within 2 or 3 

 that of the air, between 3 and 4 p. M. has been known to descend more than 27 below it, 

 and preserves an average difference of 11. 33. The range of temperature, also, is extreme. 

 The highest ever known was 90. 3; the mean, at the hottest hour, 79. 8, and of the coldest 

 hour 58. 7 ; though it was once so low as 47. 5. With the thermometer at 80 in the warmest 

 part of the day, one would suppose the heat oppressive ; and so it is, when the person is ex- 

 posed to the direct rays of the sun. But even then, evaporation is so rapid, that perspiration is 

 carried off as fast as formed, and the sensations of the body are wholly unlike those experienced 

 under the same temperature in an atmosphere loaded with moisture. Out of the sun, it is never 

 too warm for cloth clothing ; and during the first month (November) that we passed at San- 

 tiago, I often walked rapidly to the summit of Santa Lucia with a cloth coat buttoned, yet 

 failed in producing sensible moisture on the skin a climatic condition no little trying to those 

 suffering with disordered nerves. 



It has been shown, by the table of Senor Eeyes, that rain was scarcely to be expected during 

 these months ; and when by chance any fell, the quantity was so small that the atmosphere of 

 the valley immediately returned to its normal dry state. The probable progress of agriculture 

 in modifying the climate was also alluded to ; and, as testimony in support of it, nine rains 

 occurred in the nine summer months, on one of which an inch and a third of water fell in less 

 than five hours. By covering the ground with umbrageous vegetation, both the radiated and 

 absorbed heat are diminished results producing lower and more equable temperature in sum- 

 mer, whilst irrigating channels and watered fields, by exposing increased surface for evaporation, 

 augment the volume of vapor and probabilities of precipitation. An accession of clouds from 

 the same sources also diminishes the radiant heat during winter nights, and the temperature is 

 thus prevented from falling very low. Were the sky clear at the latter season, as in summer, 

 Santiago, under the joint influences of radiation and perpetual snow within twenty miles, would 

 possess a most rigorous climate. As evidence of the power of radiation in this atmosphere, on 

 the authority of the Director of the Escuela de Aries y Oficios, Prof. Domeyko publishes as 

 follows: "On the llth March, 1849, they were building a high chimney at the school named ; 

 and when the masons came down from their work at night, they left on top of the chimney, 

 overlooking all the neighboring edifices, a wooden trough containing water of little depth, 

 exposed to the action of a perfectly clear and calm sky. What was the surprise of the work- 

 men, when they returned on the following morning to conclude their job, to find about an 

 inch of ice in the trough! At daylight that morning the thermometer stood at 5 6. 5, the 

 barometer at 28.146 inches; and the phenomenon was the more notable, because, when 



