PORTO RICO EXPERIMENT STATION. 389 



A study of the above table shows that the montly rainfall goes as 

 high as 33.58 inches and as low as 0.50. A rainfall of 10 or more 

 inches in twenty-four hours is not uncommon. In July of the present 

 year a rainfall of 17 inches in twenty-four h(5urs is recorded at Haci- 

 enda Perla and of 10 inches in twenty-four hours at Adjuntas. The 

 table also shows that the driest months of the year are January, Feb- 

 ruary, March, and December. The dry season, as these months are 

 called, varies in time and duration from year to year and also varies 

 for different portions of the island. On the south side of the island 

 the dry season often continues into the month of July. During the 

 present year the fields all along the south side of the island not under 

 irrigation were in a brown and parched condition as late as July 1. 



The prevailing wind is from the northeast, and in rising to pass over 

 the mountains it is cooled to such an extent that a part of its heavy 

 charge of humidity is condensed and falls as rain on the north side of 

 the island. It is for this reason that the rainfall of the north slope so 

 far exceeds that of the south. As a rule the rains occur as showers, 

 often torrential in character, and most frequently in the afternoon. 

 After the rain the sun again shines and nature soon resumes normal 

 conditions. Owing to the torrential character of the rains a large 

 part of the water finds its way into the streams, which rush madly 

 down the steep slopes on their way to the ocean. The streams rise 

 very quickly and often become such raging torrents that it is impossi- 

 ble to cross them, and there is nothing for the traveler to do but to 

 wait for them to subside, which they usually do in a few hours. Dur- 

 ing the rainy season, however, the showers may be so frequent that 

 the streams will continue very high for several days, thus stopping for 

 the time all communication between different parts of the island. 

 Excepting on the first-class roads the streams are without bridges, and 

 even here some of these have been destroyed by the floods and will 

 have to be replaced at a cost of many thousands of dollars. 



Fogs are very common in the mountains during the early morning 

 and often settle in the valleys so as to entirely obscure the view of one 

 standing on the mountain top. 



As a whole the climate is healthful. There is usually a breeze, and 

 though the temperature is uniformly high it is seldom excessively 

 warm or oppressive. With a little care people from the temperate 

 climate need have no fear of disastrous results from the climate. It 

 is well to avoid the sun between 11 and 2 o'clock, for at that time of 

 the day it is almost directly overhead and very hot. 



SANITARY CONDITIONS. 



In the cities and towns the sanitary conditions are very bad because 

 of the lack of city water and sewerage, and the prevalence of vaults 

 that have been in use for several hundred years. (PI. XXXIII, fig. 1.) 



