24 CHAPTER III 



Honolulu, following the Nuuanu Valley. 



Altitude, feet . . . . . . 20 400 860 



Rainfall, inches . . . . 24-36 90 143 



Rainfall and Altitude in Java. 



Meester Posen Bodjong Buitzen 



Locality Batavia Cornelis Mongo Depak Geelis borg 



Distance from coast, miles 4 7 11 21 27 36 



Altitude, feet .. .. 23 46 116 304 429 874 



Rainfall, inches . . . . 71 71 96 120 146 174 



Percentage of Moisture. — Connected with the rainfall is the humidity, 

 and it naturally follows that places with heavy rainfall also have a humid 

 atmosphere. Proximity to the sea is another important factor. At 

 Honolulu, in a dry locality and near the sea, the average relative humidity 

 for the year 1901 was 70-0, with extremes of 67-2 and 76-6. At Batavia, 

 both wet and near the sea, the average for the years 1866-1900 was 82-8, 

 with monthly extremes of 77-5 and 87-5. 



The percentage of sunshine is another climatic factor of influence. It is 

 least in the marine type of climate, and over the belt of equatorial rains 

 only amounts to 45 per cent, of the possible, rising to 80 per cent, in localities, 

 such as Egypt, that belong to the continental type. 



Wind. — A climatic factor of a different type is that of wind. Generally 

 the trade winds typical of the tropics blow with a steady velocity of about 

 10 to 20 miles per hour. When the wind reaches a steady velocity of 30 

 miles per hour a cyclone is officially recorded in Mauritius, and this island 

 and the near-by one of Reunion are those which are most subject to these 

 disturbances, the centres of forty-three cyclones having passed within one 

 hundred miles of Mauritius during the years 1857-1908. Some cyclone 

 damage obtains in Mauritius about one year in three, the cyclone of May 

 29th, 1892, being one of the most destructive ever recorded. All of the West 

 Indies, with the exception of Trinidad, lie in the hurricane belt of the 

 Caribbean Sea, while Formosa is exposed to the typhoons of the China seas. 

 The Philippines just come within this region, and the crops there are occas- 

 sionally damaged. 



The Effect of Climate on the Cane. — The influence of temperature on the 

 physiology of the cane is very complex. The rate of growth, the time to 

 maturity, and the composition are all affected. In the more equatorial 

 areas the temperature variation is so small that differences in the rate of 

 growth are hard to detect. In the districts more remote from the equator 

 the influence of the cold season is pronounced. Measurements made in 

 Hawaii by Eckart^^ q^ a large number of varieties indicated that during the 

 cold season the length of internodes was generally more than 30 per cent, 

 and less than 50 per cent, of those formed in the hot season ; the diameter of 

 the stem was also less. The period taken for the cane to ripen is also depend- 

 ent on temperature. In Demerara, Bourbon canes planted in December 

 will arrow in the following September ; in places lying near the tropic 

 thirteen months is a common time. Walter^^ has observed that in Mauritius 

 canes planted near to sea level reach maturity in thirteen months, whereas 

 those planted at the 1 100-foot level require twenty-one. From a zero of 

 70° F. he has calculated that in these periods the canes receive the same 

 quantity of heat ; that is to say, the product, " days x excess daily mean 

 over 70° F.," is the same, and in this case has a numerical value of 1350. 



