TV. PREFACE. 



effects on the introduced plants, especially those from cooler climes, 

 and leaves even injurious traces on the native vegetation. 



During the blowing of a hot wind the thermometer and the wet bulb 

 thermometer show often a difference of 30° to 40°, and it is that which 

 enables persons to bear the heat of our summer and carry out their usual 

 pursuits in the field or elsewhere, which in a tropical climate would be 

 impossible. 



The changes of temperature during the summer are often very sudden, 

 so that in a short time the thermometer falls from 90° or 100° to 60° 

 or 70°. 



Our summer months are characterized by great heat, hot winds, and 

 dryness. Often not a drop of rain falls for eight or ten weeks, and it is 

 during this time that not only the indigenous but the acclimatized 

 vegetation suffers materially. The ground becomes so hot and cracks, 

 that even the occurrence of a heavy fall of rain serves only to clear the 

 leaves from dust, as it evaporates as quickly as it falls. 



The autumn season includes in Australia the months of March, April, 

 and May, and is one of our genial and beautiful parts of the year. The 

 temperature falls rapidly, only reaching 70° to 90° in the shade, the 

 mean being 64° 6' ; and in the month of May it is only 58° 2'. The 

 northern winds become cooler, the solar radiation is considerably reduced, 

 and heavy dews begin to fall at night. The indigenous Vegetation, 

 which has suffered through the summer, awakes to new life, and trees 

 and shrubs put forth fresh growth, while the leaves of the European 

 deciduous trees and shrubs get their autumnal tints and drop. 



June, July, and August constitute our winter, our rainy season, which 

 is usually marked by frequent rain and strong winds ; but it happens 

 also pften that we have to content ourselves with remarkable dry winters, 

 the mean temperature during the three months being 54° to 55° 7'. 

 Heavy hoar frosts and frosts appear often during night. The lowest 

 temperature registered iii 1876 and '77, during the month of July, has 

 been 30° and 28°, the lowest experienced in the plains near Adelaide. 

 Such heavy frosts have most disastrous effects upon the tropical and 

 subtropical plants in the gardens. 



The spring season, the most genial and most beautiful in South 

 Australia, not surpassed in any other part of the world, includes the 

 months of September, October, and November, the mean temperature 

 during the first two months being 60° to 70°. 



At this time of the year, the gardens are in their best floral beauty-^ 

 trees, shrubs, perennials, annuals, emulate each other in regard to their 

 flowers, which are of such size, richness in color, and perfection as a 



